Transcript Chapter 11 – Strings and Characters

Chapter 11 – Strings and Characters
Outline
11.1
Introduction
11.2
Fundamentals of Characters and Strings
11.3
Class String
11.3.1 String Constructors
11.3.2 String Methods length, charAt and getChars
11.3.3 Comparing Strings
11.3.4 Locating Characters and Substrings in Strings
11.3.5 Extracting Substrings from Strings
11.3.6 Concatenating Strings
11.3.7 Miscellaneous String Methods
11.3.8 String Method valueOf
11.4
Class StringBuffer
11.4.1 StringBuffer Constructors
11.4.2 StringBuffer Methods length, capacity,
setLength and ensureCapacity
11.4.3 StringBuffer Methods charAt, setCharAt,
getChars and reverse
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Chapter 11 – Strings and Characters
11.5
11.6
11.7
11.8
11.9
11.4.4 StringBuffer append Methods
11.4.5 StringBuffer Insertion and Deletion Methods
Class Character
Class StringTokenizer
Card Shuffling and Dealing Simulation
Regular Expressions, Class Pattern and Class Matcher
(Optional Case Study) Thinking About Objects: Event
Handling
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11.1 Introduction
• String and character processing
–
–
–
–
Class java.lang.String
Class java.lang.StringBuffer
Class java.lang.Character
Class java.util.StringTokenizer
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11.2 Fundamentals of Characters and
Strings
• Characters
– “Building blocks” of Java source programs
• String
– Series of characters treated as single unit
– May include letters, digits, etc.
– Object of class String
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11.3.1 String Constructors
• Class String
– Provides nine constructors
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Outline
// Fig. 11.1: StringConstructors.java
// String class constructors.
import javax.swing.*;
public class StringConstructors {
String defaultStringConstruct
constructor
ors.java
instantiates empty
string
public static void main( String args[] )
{
Constructor
char charArray[] = { 'b', 'i', 'r', 't', 'h', ' ', 'd', 'a', 'y' };
byte byteArray[] = { ( byte ) 'n', ( byte ) 'e',
Constructor
( byte ) 'w', ( byte ) ' ', ( byte ) 'y',
( byte ) 'e', ( byte ) 'a', ( byte ) 'r' };
String s = new String( "hello" );
// use
String
String
String
String
String
String
String constructors
s1 = new String();
s2 = new String( s );
s3 = new String( charArray );
s4 = new String( charArray, 6, 3 );
s5 = new String( byteArray, 4, 4 );
s6 = new String( byteArray );
LineString
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copies
Linecharacter
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copies
array
Line 19
Constructor copies
character-array subset
Line 20
Line
21array
Constructor copies
byte
Line 22
Constructor copies byte-array subset
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// append Strings to output
String output = "s1 = " + s1 + "\ns2 = " + s2 + "\ns3 = " + s3 +
"\ns4 = " + s4 + "\ns5 = " + s5 + "\ns6 = " + s6;
JOptionPane.showMessageDialog( null, output,
"String Class Constructors", JOptionPane.INFORMATION_MESSAGE );
Outline
StringConstruct
ors.java
System.exit( 0 );
}
} // end class StringConstructors
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11.3.2 String Methods length, charAt
and getChars
• Method length
– Determine String length
• Like arrays, Strings always “know” their size
• Unlike array, Strings do not have length instance variable
• Method charAt
– Get character at specific location in String
• Method getChars
– Get entire set of characters in String
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// Fig. 11.2: StringMiscellaneous.java
// This program demonstrates the length, charAt and getChars
// methods of the String class.
import javax.swing.*;
public class StringMiscellaneous {
public static void main( String args[] )
{
String s1 = "hello there";
char charArray[] = new char[ 5 ];
Outline
StringMiscellan
eous.java
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String output = "s1: " + s1;
// test length method
output += "\nLength of s1: " + s1.length();
Determine number of
characters in String s1
// loop through characters in s1 and display reversed
output += "\nThe string reversed is: ";
for ( int count = s1.length() - 1; count >= 0; count-- )
output += s1.charAt( count ) + " ";
Append s1’s characters
in reverse order to
String output
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// copy characters from string into charArray
s1.getChars( 0, 5, charArray, 0 );
output += "\nThe character array is: ";
for ( int count = 0; count < charArray.length;
output += charArray[ count ];
Outline
Copy (some of) s1’s
characters to charArray
StringMiscellan
eous.java
count++ )
Line 25
JOptionPane.showMessageDialog( null, output,
"String class character manipulation methods",
JOptionPane.INFORMATION_MESSAGE );
System.exit( 0 );
}
} // end class StringMiscellaneous
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11.3.3 Comparing Strings
• Comparing String objects
–
–
–
–
Method equals
Method equalsIgnoreCase
Method compareTo
Method regionMatches
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// Fig. 11.3: StringCompare.java
// String methods equals, equalsIgnoreCase, compareTo and regionMatches.
import javax.swing.JOptionPane;
Outline
StringCompare.j
ava
public class StringCompare {
public static void main( String args[] )
{
String s1 = new String( "hello" ); // s1 is a copy of "hello"
String s2 = "goodbye";
String s3 = "Happy Birthday";
String s4 = "happy birthday";
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String output = "s1 = " + s1 + "\ns2 = " + s2 + "\ns3 = " + s3 +
"\ns4 = " + s4 + "\n\n";
// test for equality
if ( s1.equals( "hello" ) ) // true
output += "s1 equals \"hello\"\n";
else
output += "s1 does not equal \"hello\"\n";
Method equals tests two
objects for equality using
lexicographical comparison
Equality operator (==) tests
// test for equality with ==
both object
references refer to
if ( s1 == "hello" ) // false; they are not theifsame
same object in memory
output += "s1 equals \"hello\"\n";
else
output += "s1 does not equal \"hello\"\n";
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// test for equality (ignore case)
if ( s3.equalsIgnoreCase( s4 ) ) // true
output += "s3 equals s4\n";
else
output += "s3 does not equal s4\n";
// test compareTo
output += "\ns1.compareTo( s2
"\ns2.compareTo( s1 ) is "
"\ns1.compareTo( s1 ) is "
"\ns3.compareTo( s4 ) is "
"\ns4.compareTo( s3 ) is "
)
+
+
+
+
Test two objects for
equality, but ignore case
of letters in Strings
is " + s1.compareTo( s2 ) +
s2.compareTo( s1 ) +
s1.compareTo( s1 ) +
s3.compareTo( s4 ) +
s4.compareTo( s3 ) + "\n\n";
Outline
StringCompare.j
ava
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Method compareTo
compares String objects
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Method regionMatches
// test regionMatches (case sensitive)
if ( s3.regionMatches( 0, s4, 0, 5 ) )
compares portions of two
output += "First 5 characters of s3 and s4 match\n";
String objects for equality
else
output += "First 5 characters of s3 and s4 do not match\n";
// test regionMatches (ignore case)
if ( s3.regionMatches( true, 0, s4, 0, 5 ) )
output += "First 5 characters of s3 and s4 match";
else
output += "First 5 characters of s3 and s4 do not match";
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JOptionPane.showMessageDialog( null, output,
"String comparisons", JOptionPane.INFORMATION_MESSAGE );
System.exit( 0 );
}
Outline
StringCompare.j
ava
} // end class StringCompare
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Outline
// Fig. 11.4: StringStartEnd.java
// String methods startsWith and endsWith.
import javax.swing.*;
StringStartEnd.
java
public class StringStartEnd {
public static void main( String args[] )
{
String strings[] = { "started", "starting", "ended", "ending" };
String output = "";
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// test method startsWith
for ( int count = 0; count < strings.length; count++ )
if ( strings[ count ].startsWith( "st" ) )
output += "\"" + strings[ count ] + "\" starts with \"st\"\n";
output += "\n";
// test method startsWith starting from position
// 2 of the string
for ( int count = 0; count < strings.length; count++ )
Method startsWith
determines if String starts
with specified characters
if ( strings[ count ].startsWith( "art", 2 ) )
output += "\"" + strings[ count ] +
"\" starts with \"art\" at position 2\n";
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Outline
output += "\n";
// test method endsWith
for ( int count = 0; count < strings.length; count++ )
StringStartEnd.
java
if ( strings[ count ].endsWith( "ed" ) )
output += "\"" + strings[ count ] + "\" ends with \"ed\"\n";
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Method endsWith
String ends
with specified characters
JOptionPane.showMessageDialog( null, output,
determines);if
"String Class Comparisons", JOptionPane.INFORMATION_MESSAGE
System.exit( 0 );
}
} // end class StringStartEnd
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11.3.4 Locating Characters and Substrings
in Strings
• Search for characters in String
– Method indexOf
– Method lastIndexOf
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// Fig. 11.5: StringIndexMethods.java
// String searching methods indexOf and lastIndexOf.
import javax.swing.*;
StringIndexMeth
ods.java
public class StringIndexMethods {
public static void main( String args[] )
{
String letters = "abcdefghijklmabcdefghijklm";
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indexOf finds first
occurrence of character in String
// test indexOf to locate a character in a string
Method
String output = "'c' is located at index " + letters.indexOf( 'c'
);
output += "\n'a' is located at index " + letters.indexOf( 'a', 1 );
output += "\n'$' is located at index " + letters.indexOf( '$' );
// test lastIndexOf to find a character in a string
output += "\n\nLast 'c' is located at index " +
letters.lastIndexOf( 'c' );
output += "\nLast 'a' is located at index " +
letters.lastIndexOf( 'a', 25 );
output += "\nLast '$' is located at index " +
letters.lastIndexOf( '$' );
Method lastIndexOf
finds last occurrence of
character in String
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Outline
// test indexOf to locate a substring in a string
output += "\n\n\"def\" is located at index " +
letters.indexOf( "def" );
StringIndexMeth
ods.java
output += "\n\"def\" is located at index " +
letters.indexOf( "def", 7 );
output += "\n\"hello\" is located at index " +
letters.indexOf( "hello" );
// test lastIndexOf to find a substring in a string
output += "\n\nLast \"def\" is located at index " +
letters.lastIndexOf( "def" );
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Methods indexOf and
lastIndexOf can also find
occurrences of substrings
output += "\nLast \"def\" is located at index " +
letters.lastIndexOf( "def", 25 );
output += "\nLast \"hello\" is located at index " +
letters.lastIndexOf( "hello" );
JOptionPane.showMessageDialog( null, output,
"String searching methods", JOptionPane.INFORMATION_MESSAGE );
System.exit( 0 );
}
}
// end class StringIndexMethods
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Outline
StringIndexMeth
ods.java
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11.3.5 Extracting Substrings from Strings
• Create Strings from other Strings
– Method substring
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Outline
// Fig. 11.6: SubString.java
// String class substring methods.
import javax.swing.*;
SubString.java
public class SubString {
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public static void main( String args[] )
{
String letters = "abcdefghijklmabcdefghijklm";
// test substring methods
String output = "Substring from index 20 to end is " +
"\"" + letters.substring( 20 ) + "\"\n";
output += "Substring from index 3 up to 6 is " +
"\"" + letters.substring( 3, 6 ) + "\"";
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Beginning at index 20,
extract characters from
String letters
Extract characters from index 3
to 6 from String letters
JOptionPane.showMessageDialog( null, output,
"String substring methods", JOptionPane.INFORMATION_MESSAGE );
System.exit( 0 );
}
} // end class SubString
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11.3.6 Concatenating Strings
• Method concat
– Concatenate two String objects
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Outline
// Fig. 11.7: StringConcatenation.java
// String concat method.
import javax.swing.*;
StringConcatena
tion.java
public class StringConcatenation {
public static void main( String args[] )
{
String s1 = new String( "Happy " );
String s2 = new String( "Birthday" );
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Concatenate String s2
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to String s1
String output = "s1 = " + s1 + "\ns2 = " + s2;
output += "\n\nResult of s1.concat( s2 ) = " + s1.concat( s2 );
output += "\ns1 after concatenation = " + s1;
However, String s1 is not
modified by method concat
JOptionPane.showMessageDialog( null, output,
"String method concat", JOptionPane.INFORMATION_MESSAGE );
System.exit( 0 );
}
} // end class StringConcatenation
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11.3.7 Miscellaneous String Methods
• Miscellaneous String methods
– Return modified copies of String
– Return character array
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// Fig. 11.8: StringMiscellaneous2.java
// String methods replace, toLowerCase, toUpperCase, trim and toCharArray.
import javax.swing.*;
StringMiscellan
eous2.java
public class StringMiscellaneous2 {
public static void
{
String s1 = new
String s2 = new
String s3 = new
Outline
main( String args[] )
String( "hello" );
String( "GOODBYE" );
String( "
spaces
" );
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Use method replace to return s1
copy in which every occurrence of
Line 20
‘l’ is replaced with ‘L’
Line 21 to
toUpperCase
return s1 copy in which every
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character is uppercase
String output = "s1 = " + s1 + "\ns2 = " + s2 + "\ns3 = "
+ s3;
Use
method
// test method replace
output += "\n\nReplace 'l' with 'L' in s1: " +
s1.replace( 'l', 'L' );
// test toLowerCase and toUpperCase
output += "\n\ns1.toUpperCase() = " + s1.toUpperCase()
"\ns2.toLowerCase() = " + s2.toLowerCase();
// test trim method
output += "\n\ns3 after trim = \"" + s3.trim() + "\"";
Use method toLowerCase to
return s2 copy in which every
+
character is uppercase
Use method trim to
return s3 copy in which
whitespace is eliminated
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// test toCharArray method
char charArray[] = s1.toCharArray();
output += "\n\ns1 as a character array = ";
Use method toCharArray to
return character array of s1
for ( int count = 0; count < charArray.length; ++count )
output += charArray[ count ];
JOptionPane.showMessageDialog( null, output,
"Additional String methods", JOptionPane.INFORMATION_MESSAGE );
Outline
StringMiscellan
eous2.java
Line 27
System.exit( 0 );
}
} // end class StringMiscellaneous2
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11.3.8 String Method valueOf
• String provides static class methods
– Method valueOf
• Returns String representation of object, data, etc.
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// Fig. 11.9: StringValueOf.java
// String valueOf methods.
import javax.swing.*;
public class StringValueOf {
public static void main( String args[] )
{
char charArray[] = { 'a', 'b', 'c', 'd', 'e', 'f' };
boolean booleanValue = true;
char characterValue = 'Z';
int integerValue = 7;
long longValue = 10000000L;
float floatValue = 2.5f; // f suffix indicates that 2.5 is a float
double doubleValue = 33.333;
Object objectRef = "hello"; // assign string to an Object reference
Outline
StringValueOf.j
ava
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String output = "char array = " + String.valueOf( charArray ) +
"\npart of char array = " + String.valueOf( charArray, 3, 3 ) +
"\nboolean = " + String.valueOf( booleanValue ) +
"\nchar = " + String.valueOf( characterValue ) +
static method valueOf of
"\nint = " + String.valueOf( integerValue ) +
class String returns String
"\nlong = " + String.valueOf( longValue ) +
"\nfloat = " + String.valueOf( floatValue ) +
representation of various types
"\ndouble = " + String.valueOf( doubleValue ) +
"\nObject = " + String.valueOf( objectRef );
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JOptionPane.showMessageDialog( null, output,
"String valueOf methods", JOptionPane.INFORMATION_MESSAGE );
System.exit( 0 );
}
Outline
StringValueOf.j
ava
} // end class StringValueOf
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11.4 Class StringBuffer
• Class StringBuffer
– When String object is created, its contents cannot change
– Used for creating and manipulating dynamic string data
• i.e., modifiable Strings
– Can store characters based on capacity
• Capacity expands dynamically to handle additional characters
– Uses operators + and += for String concatenation
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11.4.1 StringBuffer Constructors
• Three StringBuffer constructors
– Default creates StringBuffer with no characters
• Capacity of 16 characters
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Outline
// Fig. 11.10: StringBufferConstructors.java
// StringBuffer constructors.
import javax.swing.*;
Default constructor creates
empty StringBuffer with
capacity of StringBufferCon
16 characters
structors.java
public class StringBufferConstructors {
public static void main( String args[] )
{
StringBuffer buffer1 = new StringBuffer();
StringBuffer buffer2 = new StringBuffer( 10 );
StringBuffer buffer3 = new StringBuffer( "hello" );
Second constructor creates empty
Line 9
StringBuffer with capacity of
specified (10) characters
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String output = "buffer1 = \"" + buffer1.toString() + "\"" +
"\nbuffer2 = \"" + buffer2.toString() + "\"" +
"\nbuffer3 = \"" + buffer3.toString() + "\"";
Third constructor creates
Line 11
StringBuffer with
String “hello” and
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capacity of 16 characters
JOptionPane.showMessageDialog( null, output,
"StringBuffer constructors", JOptionPane.INFORMATION_MESSAGE Method
);
System.exit( 0 );
}
toString returns
String representation of
StringBuffer
} // end class StringBufferConstructors
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11.4.2 StringBuffer Methods length, capacity,
setLength and ensureCapacity
• Method length
– Return StringBuffer length
• Method capacity
– Return StringBuffer capacity
• Method setLength
– Increase or decrease StringBuffer length
• Method ensureCapacity
– Set StringBuffer capacity
– Guarantee that StringBuffer has minimum capacity
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// Fig. 11.11: StringBufferCapLen.java
// StringBuffer length, setLength, capacity and ensureCapacity methods.
import javax.swing.*;
StringBufferCap
Len.java
public class StringBufferCapLen {
public static void main( String args[] )
{
StringBuffer buffer = new StringBuffer( "Hello, how are you?" );
String output = "buffer = " + buffer.toString() + "\nlength = " +
buffer.length() + "\ncapacity = " + buffer.capacity();
buffer.ensureCapacity( 75 );
output += "\n\nNew capacity = " + buffer.capacity();
buffer.setLength( 10 );
output += "\n\nNew length = " + buffer.length() +
"\nbuf = " + buffer.toString();
JOptionPane.showMessageDialog( null, output,
"StringBuffer length and capacity Methods",
JOptionPane.INFORMATION_MESSAGE );
Outline
Method length
Line 12 returns
StringBuffer length
Line 12
Method capacity returns
StringBuffer
Line 14 capacity
Line 17
Use method ensureCapacity
to set capacity to 75
Use method setLength
to set length to 10
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System.exit( 0 );
}
} // end class StringBufferCapLen
Outline
StringBufferCap
Len.java
Only 10 characters
from
StringBuffer are
printed
Only 10 characters from
StringBuffer are printed
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11.4.3 StringBuffer Methods charAt,
setCharAt, getChars and reverse
• Manipulating StringBuffer characters
– Method charAt
• Return StringBuffer character at specified index
– Method setCharAt
• Set StringBuffer character at specified index
– Method getChars
• Return character array from StringBuffer
– Method reverse
• Reverse StringBuffer contents
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// Fig. 11.12: StringBufferChars.java
// StringBuffer methods charAt, setCharAt, getChars and reverse.
import javax.swing.*;
public class StringBufferChars {
public static void main( String args[] )
{
StringBuffer buffer = new StringBuffer( "hello there" );
String output = "buffer = " + buffer.toString() +
"\nCharacter at 0: " + buffer.charAt( 0 ) +
"\nCharacter at 4: " + buffer.charAt( 4 );
char charArray[] = new char[ buffer.length() ];
buffer.getChars( 0, buffer.length(), charArray, 0 );
output += "\n\nThe characters are: ";
Outline
StringBufferCha
rs.java
Lines 12-13
Return StringBuffer
characters at indices 0
Line 16
and 4, respectively
Lines 22-23
Return character array
from StringBuffer
for ( int count = 0; count < charArray.length; ++count )
output += charArray[ count ];
buffer.setCharAt( 0, 'H' );
buffer.setCharAt( 6, 'T' );
output += "\n\nbuf = " + buffer.toString();
Replace characters at
indices 0 and 6 with ‘H’
and ‘T,’ respectively
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buffer.reverse();
output += "\n\nbuf = " + buffer.toString();
JOptionPane.showMessageDialog( null, output,
"StringBuffer character methods",
JOptionPane.INFORMATION_MESSAGE );
System.exit( 0 );
Outline
Reverse characters in
StringBuffer
StringBufferCha
rs.java
Lines 26
}
} // end class StringBufferChars
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All rights reserved.
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11.4.4 StringBuffer append Methods
• Method append
– Allow data values to be added to StringBuffer
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Outline
// Fig. 11.13: StringBufferAppend.java
// StringBuffer append methods.
import javax.swing.*;
StringBufferApp
end.java
public class StringBufferAppend {
public static void main( String args[] )
{
Object objectRef = "hello";
String string = "goodbye";
char charArray[] = { 'a', 'b', 'c', 'd', 'e', 'f' };
boolean booleanValue = true;
char characterValue = 'Z';
int integerValue = 7;
long longValue = 10000000;
float floatValue = 2.5f; // f suffix indicates 2.5 is a float
double doubleValue = 33.333;
StringBuffer lastBuffer = new StringBuffer( "last StringBuffer" );
StringBuffer buffer = new StringBuffer();
buffer.append(
buffer.append(
buffer.append(
buffer.append(
buffer.append(
buffer.append(
buffer.append(
Line 21
Line 23
Line 25
Line 27
Append String “hello”
objectRef );
to StringBuffer
" " );
// each of these contains two spaces
string );
Append String “goodbye”
" " );
charArray );
Append “a b c d e f”
" " );
charArray, 0, 3 );
Append “a b c”
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buffer.append(
buffer.append(
buffer.append(
buffer.append(
buffer.append(
buffer.append(
buffer.append(
buffer.append(
buffer.append(
buffer.append(
buffer.append(
buffer.append(
buffer.append(
buffer.append(
" " );
booleanValue );
" " );
characterValue );
" " );
integerValue );
" " );
longValue );
" " );
floatValue );
" " );
doubleValue );
" " );
lastBuffer );
Outline
StringBufferApp
Append boolean, char,
int,
end.java
long, float and double
Line 29-39
JOptionPane.showMessageDialog( null,
"buffer = " + buffer.toString(), "StringBuffer append Methods",
JOptionPane.INFORMATION_MESSAGE );
System.exit( 0 );
}
} // end StringBufferAppend
 2003 Prentice Hall, Inc.
All rights reserved.
11.4.5 StringBuffer Insertion and Deletion
Methods
• Method insert
– Allow data-type values to be inserted into StringBuffer
• Methods delete and deleteCharAt
– Allow characters to be removed from StringBuffer
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// Fig. 11.14: StringBufferInsert.java
// StringBuffer methods insert and delete.
import javax.swing.*;
public class StringBufferInsert {
public static void main( String args[] )
{
Object objectRef = "hello";
String string = "goodbye";
char charArray[] = { 'a', 'b', 'c', 'd', 'e', 'f' };
boolean booleanValue = true;
char characterValue = 'K';
int integerValue = 7;
long longValue = 10000000;
float floatValue = 2.5f; // f suffix indicates that 2.5 is a float
double doubleValue = 33.333;
StringBuffer buffer = new StringBuffer();
buffer.insert(
buffer.insert(
buffer.insert(
buffer.insert(
buffer.insert(
buffer.insert(
buffer.insert(
0,
0,
0,
0,
0,
0,
0,
Outline
StringBufferIns
ert.java
Lines 20-26
objectRef );
" " ); // each of these contains two spaces
string );
" " );
Use method insert to insert
charArray );
data in beginning of
" " );
charArray, 3, 3 );
StringBuffer
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buffer.insert(
buffer.insert(
buffer.insert(
buffer.insert(
buffer.insert(
buffer.insert(
buffer.insert(
buffer.insert(
buffer.insert(
buffer.insert(
buffer.insert(
buffer.insert(
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
Outline
" " );
booleanValue );
" " );
characterValue );
" " );
integerValue );
" " );
longValue );
" " );
floatValue );
" " );
doubleValue );
Use method insert to insertStringBufferIns
ert.java
data in beginning of
StringBuffer
Lines 27-38
String output = "buffer after inserts:\n" +
buffer.deleteCharAt( 10 );
buffer.delete( 2, 6 );
Line 42
Use method deleteCharAt to
Lineindex
43 10 in
remove character from
buffer.toString(); StringBuffer
// delete 5 in 2.5
// delete .333 in 33.333
output += "\n\nbuffer after deletes:\n" +
Remove characters from
buffer.toString(); indices 2 through 5 (inclusive)
JOptionPane.showMessageDialog( null, output,
"StringBuffer insert/delete", JOptionPane.INFORMATION_MESSAGE );
System.exit( 0 );
}
} // end class StringBufferInsert
 2003 Prentice Hall, Inc.
All rights reserved.
Outline
StringBufferIns
ert.java
 2003 Prentice Hall, Inc.
All rights reserved.
47
11.5 Class Character
• Treat primitive variables as objects
– Type wrapper classes
• Boolean
• Character
• Double
• Float
• Byte
• Short
• Integer
• Long
– We examine class Character
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// Fig. 11.15: StaticCharMethods.java
// Static Character testing methods and case conversion methods.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
Outline
StaticCharMetho
ds.java
public class StaticCharMethods extends JFrame {
private char c;
private JLabel promptLabel;
private JTextField inputField;
private JTextArea outputArea;
// constructor builds GUI
public StaticCharMethods()
{
super( "Static Character Methods" );
Container container = getContentPane();
container.setLayout( new FlowLayout() );
promptLabel = new JLabel( "Enter a character and press Enter" );
container.add( promptLabel );
inputField = new JTextField( 5 );
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inputField.addActionListener(
new ActionListener() {
Outline
// anonymous inner class
// handle textfield event
public void actionPerformed( ActionEvent event )
{
String s = event.getActionCommand();
c = s.charAt( 0 );
buildOutput();
}
StaticCharMetho
ds.java
} // end anonymous inner class
); // end call to addActionListener
container.add( inputField );
outputArea = new JTextArea( 10, 20 );
container.add( outputArea );
setSize( 300, 220 );
setVisible( true );
// set the window size
// show the window
} // end constructor
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Outline
// display character info in outputArea
private void buildOutput()
{
outputArea.setText( "is defined: " + Character.isDefined(Determine
c ) +
whetherStaticCharMetho
c is
"\nis digit: " + Character.isDigit( c ) +
defined Unicode digit
ds.java
"\nis first character in a Java identifier: " +
Character.isJavaIdentifierStart( c ) +
Determine whether c can be used
Line 54
"\nis part of a Java identifier: " +
as
first
character
in identifier
Character.isJavaIdentifierPart( c ) +
"\nis letter: " + Character.isLetter( c ) +
Line 56
"\nis letter or digit: " + Character.isLetterOrDigit( c ) + Determine whether c can be
"\nis lower case: " + Character.isLowerCase( c ) +
used as identifier
character
Line 58
"\nis upper case: " + Character.isUpperCase( c ) +
"\nto upper case: " + Character.toUpperCase( c ) +
Determine whether c is a letter
"\nto lower case: " + Character.toLowerCase( c ) );
Line 59
}
// create StaticCharMethods object to begin execution
public static void main( String args[] )
{
StaticCharMethods application = new StaticCharMethods();
application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
}
Determine whether
Line
60 or digit
c is
letter
Lines
61-62c is
Determine
whether
uppercase or lowercase
} // end class StaticCharMethods
 2003 Prentice Hall, Inc.
All rights reserved.
Outline
StaticCharMetho
ds.java
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// Fig. 11.15: StaticCharMethods2.java
// Static Character conversion methods.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
Outline
StaticCharMetho
ds2.java
public class StaticCharMethods2 extends JFrame {
private char c;
private int digit, radix;
private JLabel prompt1, prompt2;
private JTextField input, radixField;
private JButton toChar, toInt;
// constructor builds GUI
public StaticCharMethods2()
{
super( "Character Conversion Methods" );
Container container = getContentPane();
container.setLayout( new FlowLayout() );
prompt1 = new JLabel( "Enter a digit or character " );
input = new JTextField( 5 );
container.add( prompt1 );
container.add( input );
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Outline
prompt2 = new JLabel( "Enter a radix " );
radixField = new JTextField( 5 );
container.add( prompt2 );
container.add( radixField );
StaticCharMetho
ds2.java
toChar = new JButton( "Convert digit to character" );
toChar.addActionListener(
Line 44
new ActionListener() { // anonymous inner class
// handle toChar JButton event
public void actionPerformed( ActionEvent actionEvent )
{
digit = Integer.parseInt( input.getText() );
radix = Integer.parseInt( radixField.getText() );
JOptionPane.showMessageDialog( null,
"Convert digit to character: " +
Character.forDigit( digit, radix ) );
}
} // end anonymous inner class
); // end call to addActionListener
Use method forDigit to convert
int digit to number-system
character specified by int radix
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toInt = new JButton( "Convert character to digit" );
toInt.addActionListener(
new ActionListener() {
// anonymous inner class
// handle toInt JButton event
public void actionPerformed( ActionEvent actionEvent )
{
String s = input.getText();
c = s.charAt( 0 );
radix = Integer.parseInt( radixField.getText() );
JOptionPane.showMessageDialog( null,
"Convert character to digit: " +
Character.digit( c, radix ) );
}
} // end anonymous inner class
); // end call to addActionListener
Outline
StaticCharMetho
ds2.java
Line 64
Use method digit to convert
char c to number-system
integer specified by int radix
container.add( toChar );
container.add( toInt );
setSize( 275, 150 ); // set the window size
setVisible( true );
// show the window
}
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All rights reserved.
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// create StaticCharMethods2 object execute application
public static void main( String args[] )
{
StaticCharMethods2 application = new StaticCharMethods2();
application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
}
Outline
StaticCharMetho
ds2.java
} // end class StaticCharMethods2
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// Fig. 11.17: OtherCharMethods.java
// Non-static Character methods.
import javax.swing.*;
public class OtherCharMethods {
public static void main( String args[] )
{
Character c1 = new Character( 'A' );
Character c2 = new Character( 'a' );
String output = "c1 = " + c1.charValue() +
"\nc2 = " + c2.toString();
Outline
OtherCharMethod
s.java
Lines 12-15
Characters non-static methods
charValue, toString and equals
if ( c1.equals( c2 ) )
output += "\n\nc1 and c2 are equal";
else
output += "\n\nc1 and c2 are not equal";
JOptionPane.showMessageDialog( null, output,
"Non-static Character methods",
JOptionPane.INFORMATION_MESSAGE );
System.exit( 0 );
}
} // end class OtherCharMethods
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All rights reserved.
57
11.6 Class StringTokenizer
• Tokenizer
– Partition String into individual substrings
– Use delimiter
– Java offers java.util.StringTokenizer
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Outline
// Fig. 11.18: TokenTest.java
// StringTokenizer class.
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
TokenTest.java
Line 24
public class TokenTest extends JFrame {
private JLabel promptLabel;
private JTextField inputField;
private JTextArea outputArea;
// set up GUI and event handling
public TokenTest()
{
super( "Testing Class StringTokenizer" );
Container container = getContentPane();
container.setLayout( new FlowLayout() );
promptLabel = new JLabel( "Enter a sentence and press Enter" );
container.add( promptLabel );
inputField = new JTextField( 20 );
inputField contains String to
be parsed by StringTokenizer
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Outline
inputField.addActionListener(
new ActionListener() {
// anonymous inner class
Use StringTokenizer to parse
String
TokenTest.java
using default delimiter “ \n\t\r”
// handle text field event
public void actionPerformed( ActionEvent event )
{
StringTokenizer tokens =
new StringTokenizer( event.getActionCommand() );
outputArea.setText( "Number of elements: " +
tokens.countTokens() + "\nThe tokens are:\n" );
Line 33
Line
Count number
of36
tokens
Lines 38-39
while ( tokens.hasMoreTokens() )
outputArea.append( tokens.nextToken() + "\n" );
}
} // end anonymous inner class
Append next token to outputArea,
as long as tokens exist
); // end call to addActionListener
container.add( inputField );
outputArea = new JTextArea( 10, 20 );
outputArea.setEditable( false );
container.add( new JScrollPane( outputArea ) );
setSize( 275, 240 ); // set the window size
setVisible( true );
// show the window
}
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// execute application
public static void main( String args[] )
{
TokenTest application = new TokenTest();
application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
}
Outline
TokenTest.java
} // end class TokenTest
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All rights reserved.
61
11.7 Card Shuffling and Dealing Simulation
• Develop DeckOfCards application
–
–
–
–
Create deck of 52 playing cards using Card objects
User deals card by clicking “Deal card” button
User shuffles deck by clicking “Shuffle cards” button
Use random-number generation
 2003 Prentice Hall, Inc. All rights reserved.
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Outline
// Fig. 11.19: DeckOfCards.java
// Card shuffling and dealing program.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
DeckOfCards.jav
a
public class DeckOfCards extends JFrame {
private Card deck[];
private int currentCard;
private JButton dealButton, shuffleButton;
private JTextField displayField;
private JLabel statusLabel;
// set up deck of cards and GUI
public DeckOfCards()
{
super( "Card Dealing Program" );
Lines 19 and 29
Line 30
Deck of 52 Cards
String faces[] = { "Ace", "Deuce", "Three", "Four", "Five", "Six",
"Seven", "Eight", "Nine", "Ten", "Jack", "Queen", "King" };
String suits[] = { "Hearts", "Diamonds", "Clubs", "Spades" };
deck = new Card[ 52 ];
currentCard = -1;
Most recently dealt Cards in deck array
(-1 if no Cards have been dealt)
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// populate deck with Card objects
for ( int count = 0; count < deck.length; count++ )
deck[ count ] = new Card( faces[ count % 13 ],
suits[ count / 13 ] );
// set up GUI and event handling
Container container = getContentPane();
container.setLayout( new FlowLayout() );
Outline
Fill deck array with Cards
DeckOfCards.jav
a
Lines 27-29
dealButton = new JButton( "Deal card" );
dealButton.addActionListener(
new ActionListener() {
// anonymous inner
Line 43
When user presses Deal Card
Line 46
class button, method dealCard
gets next card in deck array
// deal one card
public void actionPerformed( ActionEvent actionEvent )
{
Card dealt = dealCard();
Display Card in JTextField
if ( dealt != null ) {
displayField.setText( dealt.toString() );
statusLabel.setText( "Card #: " + currentCard );
}
else {
displayField.setText( "NO MORE CARDS TO DEAL" );
statusLabel.setText( "Shuffle cards to continue" );
}
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All rights reserved.
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} // end anonymous inner class
); // end call to addActionListener
container.add( dealButton );
shuffleButton = new JButton( "Shuffle cards" );
shuffleButton.addActionListener(
new ActionListener() {
Outline
DeckOfCards.jav
a
Line 70
// anonymous inner class
// shuffle deck
public void actionPerformed( ActionEvent actionEvent )
{
displayField.setText( "SHUFFLING ..." );
shuffle();
displayField.setText( "DECK IS SHUFFLED" );
}
When user presses Shuffle
Cards button, method
shuffle shuffles cards
} // end anonymous inner class
); // end call to addActionListener
container.add( shuffleButton );
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displayField = new JTextField( 20 );
displayField.setEditable( false );
container.add( displayField );
statusLabel = new JLabel();
container.add( statusLabel );
Outline
DeckOfCards.jav
a
Lines 92-102
setSize( 275, 120 );
setVisible( true );
// set window size
// show window
}
// shuffle deck of cards with one-pass algorithm
private void shuffle()
{
currentCard = -1;
// for each card, pick another random card and swap them
for ( int first = 0; first < deck.length; first++ ) {
int second = ( int ) ( Math.random() * 52 );
Card temp = deck[ first ];
deck[ first ] = deck[ second ];
deck[ second ] = temp;
}
Shuffle cards by swapping
each Card with randomly
selected Card
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All rights reserved.
Outline
104
dealButton.setEnabled( true );
105
}
106
107
// deal one card
DeckOfCards.jav
108
private Card dealCard()
If deck is not empty, a Card
a
109
{
object reference is returned;
110
if ( ++currentCard < deck.length )
otherwise, null is returned
Lines 108-116
111
return deck[ currentCard ];
112
else {
113
dealButton.setEnabled( false );
Lines 114 and 123
Method setEnabled enables
114
return null;
and disables JButton
115
}
116
}
117
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// execute application
119
public static void main( String args[] )
120
{
121
DeckOfCards application = new DeckOfCards();
122
123
application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
124
}
125
126 } // end class DeckOfCards
127
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All rights reserved.
128 // class to represent a card
129 class Card {
Store face name and suit for
130
private String face;
specific Card, respectively
131
private String suit;
132
133
// constructor to initialize a card
134
public Card( String cardFace, String cardSuit )
135
{
136
face = cardFace;
137
suit = cardSuit;
138
}
139
140
// return String represenation of Card
141
public String toString()
142
{
143
return face + " of " + suit;
144
}
145
146 } // end class Card
Outline
DeckOfCards.jav
a
Lines 130-131
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All rights reserved.
11.8 Regular Expressions, Class Pattern
and Class Matcher
• Regular expression
– Sequence of characters and symbols
– Define set of strings
• Class Pattern
– An immutable regular expression
• Class Match
– A regular expression matching operation
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11.8 Regular Expressions, Class Pattern
and Class Matcher
Character
\d
Matches
Matches
any digit
Character
\D
\w
any word character
\W
any non-word character
\s
any whitespace
\S
any non-whitespace
Fig. 11.20 Predefined character classes.
 2003 Prentice Hall, Inc. All rights reserved.
any non-digit
69
11.8 Regular Expressions, Class Pattern
and Class Matcher
Quantifier
Matches
*
Matches zero or more occurrences of the pattern.
+
Matches one or more occurrences of the pattern.
?
Matches zero or one occurrences of the pattern.
{n}
Matches exactly n occurrences.
{n,}
Matches at least n occurrences.
{n,m}
Matches between n and m (inclusive) occurrences.
Fig. 11.22 Quantifiers used regular expressions.
 2003 Prentice Hall, Inc. All rights reserved.
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// Fig. 11.21: ValidateFrame.java
// Validate user information using regular expressions.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
Outline
ValidateFrame.j
ava
public class ValidateFrame extends JFrame {
private JTextField phoneTextField, zipTextField, stateTextField,
cityTextField, addressTextField, firstTextField, lastTextField;
public ValidateFrame()
{
super( "Validate" );
// create the GUI components
JLabel phoneLabel = new JLabel( "Phone" );
JLabel zipLabel = new JLabel( "Zip" );
JLabel stateLabel = new JLabel( "State" );
JLabel cityLabel = new JLabel( "City" );
JLabel addressLabel = new JLabel( "Address" );
JLabel firstLabel = new JLabel( "First Name" );
JLabel lastLabel = new JLabel( "Last Name" );
JButton okButton = new JButton( "OK" );
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All rights reserved.
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okButton.addActionListener(
Outline
new ActionListener() { // inner class
public void actionPerformed( ActionEvent event ) {
validateDate();
}
ValidateFrame.j
ava
} // end inner class
); // end call to addActionListener
phoneTextField = new JTextField( 15 );
zipTextField = new JTextField( 5 );
stateTextField = new JTextField( 2 );
cityTextField = new JTextField( 12 );
addressTextField = new JTextField( 20 );
firstTextField = new JTextField( 20 );
lastTextField = new JTextField( 20 );
JPanel firstName = new JPanel();
firstName.add( firstLabel );
firstName.add( firstTextField );
JPanel lastName = new JPanel();
lastName.add( lastLabel );
lastName.add( lastTextField );
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JPanel address1 = new JPanel();
address1.add( addressLabel );
address1.add( addressTextField );
JPanel address2 = new JPanel();
address2.add( cityLabel );
address2.add( cityTextField );
address2.add( stateLabel );
address2.add( stateTextField );
address2.add( zipLabel );
address2.add( zipTextField );
Outline
ValidateFrame.j
ava
JPanel phone = new JPanel();
phone.add( phoneLabel );
phone.add( phoneTextField );
JPanel ok = new JPanel();
ok.add( okButton );
// add the components to the application
Container container = getContentPane();
container.setLayout( new GridLayout( 6, 1 ) );
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container.add(
container.add(
container.add(
container.add(
container.add(
container.add(
firstName );
lastName );
address1 );
address2 );
phone );
ok );
Outline
ValidateFrame.j
ava
setSize( 325, 225 );
setVisible( true );
} // end ValidateFrame constructor
public static void main( String args[] )
{
ValidateFrame application = new ValidateFrame();
application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
}
// handles okButton action event
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All rights reserved.
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private void validateDate()
{
// ensure that no textboxes are empty
if ( lastTextField.getText().equals( "" ) ||
firstTextField.getText().equals( "" ) ||
addressTextField.getText().equals( "" ) ||
cityTextField.getText().equals( "" ) ||
stateTextField.getText().equals( "" ) ||
zipTextField.getText().equals( "" ) ||
phoneTextField.getText().equals( "" ) ) // end condition
Outline
ValidateFrame.j
ava
Lines 109-118
JOptionPane.showMessageDialog( this, "Please fill all fields" );
// if first name format invalid show message
else if ( !firstTextField.getText().matches( "[A-Z][a-zA-Z]*" ) )
JOptionPane.showMessageDialog( this, "Invalid first name" );
Matches returns true if the
the regular
// if last name format invalid show message
String
else if ( !lastTextField.getText().matches( "[A-Z][a-zA-Z]*"
) ) matches
JOptionPane.showMessageDialog( this, "Invalid last name"
);
expression
// if address format invalid show message
else if ( !addressTextField.getText().matches(
"\\d+\\s+([a-zA-Z]+|[a-zA-Z]+\\s[a-zA-Z]+)" ) )
JOptionPane.showMessageDialog( this, "Invalid address" );
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Outline
121
// if city format invalid show message
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else if ( !cityTextField.getText().matches(
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"([a-zA-Z]+|[a-zA-Z]+\\s[a-zA-Z]+)" ) )
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JOptionPane.showMessageDialog( this, "Invalid city" );
ValidateFrame.j
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ava
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// if state format invalid show message
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else if ( !stateTextField.getText().matches(
Lines 122-137
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"([a-zA-Z]+|[a-zA-Z]+\\s[a-zA-Z]+)" ) )
Matches returns true if the
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JOptionPane.showMessageDialog( this, "Invalid state" );
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String matches the regular
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// if zip code format invalid show message
expression
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else if ( !zipTextField.getText().matches( "\\d{5}" ) )
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JOptionPane.showMessageDialog( this, "Invalid zip code" );
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// if phone number format invalid show message
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else if ( !phoneTextField.getText().matches(
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"[1-9]\\d{2}-[1-9]\\d{2}-\\d{4}" ) )
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JOptionPane.showMessageDialog( this, "Invalid phone number" );
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else // information is valid, signal user
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JOptionPane.showMessageDialog( this, "Thank you" );
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} // end method validateDate
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145 } // end class ValidateFrame
 2003 Prentice Hall, Inc.
All rights reserved.
Outline
ValidateFrame.j
ava
Error message if
TextBox left blank
Signal that the “Zip” TextBox
was entered improperly
Signify that all the TextBoxes
were entered in correct format
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All rights reserved.
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Outline
// Fig. 11.23: RegexSubstitution.java
// Using methods replaceFirst, replaceAll and split.
import javax.swing.*;
RegexSubstituti
public class RegexSubstitution
on.java
{
public static void main( String args[] )
Line 15
{
Replace
every
instance
of
“*”
String firstString = "This sentence ends in 5 stars *****";
String secondString = "1, 2, 3, 4, 5, 6, 7, 8"; in firstString with “^”
Line 20
String output = "Original String 1: " + firstString;
// replace '*' with '^'
firstString = firstString.replaceAll( "\\*", "^"
Line 26
Replace every instance of “stars”
in firstString with “carets”
);
output += "\n^ substituted for *: " + firstString;
// replace 'stars' with 'carets'
Replace every word
firstString = firstString.replaceAll( "stars", "carets" );
in
firstString with “word”
output += "\n\"carets\" substituted for \"stars\": " + firstString;
// replace words with 'word'
output += "\nEvery word replaced by \"word\": " +
firstString.replaceAll( "\\w+", "word" );
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output += "\n\nOriginal String 2: " + secondString;
Outline
replaceFirst replaces a single
RegexSubstituti
expression
on.java
// replace first three digits with 'digit'
occurrence of the regular
for ( int i = 0; i < 3; i++ )
secondString = secondString.replaceFirst( "\\d", "digit" );
output += "\nFirst 3 digits replaced by \"digit\" : " +
secondString;
output += "\nString split at commas: [";
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String[] results = secondString.split( ",\\s*" ); // split on commas
for ( int i = 0; i < results.length; i++ ) split returns array
output += "\"" + results[ i ] + "\", "; // output results
of substrings between
matches of the regular expression
// remove the extra comma and add a bracket
output = output.substring( 0, output.length() - 2 ) + "]";
JOptionPane.showMessageDialog( null, output );
System.exit( 0 );
} // end method main
} // end class RegexSubstitution
 2003 Prentice Hall, Inc.
All rights reserved.
Outline
RegexSubstituti
on.java
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All rights reserved.
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Outline
// Fig. 11.24: RegexMatches.java
// Demonstrating Classes Pattern and Matcher.
import java.util.regex.*;
import javax.swing.*;
class RegexMatches
{
public static void main( String args[] )
{
String output = "";
RegexMatches.ja
va
Lines 13-14
compile creates an immutable
Line 22
regular expression object
// create regular expression
Pattern expression =
Pattern.compile( "J.*\\d[0-35-9]-\\d\\d-\\d\\d" );
String string1 = "Jane's Birthday is 05-12-75\n" +
"Dave's Birthday is 11-04-68\n" +
matcher associates
"John's Birthday is 04-28-73\n" +
object with a string
"Joe's Birthday is 12-17-77";
Line 24
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a Pattern
// match regular expression to string and print matches
Matcher matcher = expression.matcher( string1 );
while ( matcher.find() )
output += matcher.group() + "\n";
find gets the first substring that
matches the regular expression
group returns the
matched substring
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JOptionPane.showMessageDialog( null, output );
System.exit( 0 );
} // end main
Outline
RegexMatches.ja
va
} // end class RegexMatches
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All rights reserved.
11.9 (Optional Case Study) Thinking About
Objects: Event Handling
• How objects interact
– Sending object sends message to receiving object
– We discuss how elevator-system objects interact
• Model system behavior
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83
11.9 (Optional Case Study) Thinking About
Objects: Event Handling
• Event
– Message that notifies an object of an action
• Action: Elevator arrives at Floor
• Consequence: Elevator sends elevatorArrived event
to Elevator’s Door
– i.e., Door is “notified” that Elevator has arrived
• Action: Elevator’s Door opens
• Consequence: Door sends doorOpened event to Person
– i.e., Person is “notified” that Door has opened
– Preferred naming structure
• Noun (“elevator”) preceded by verb (“arrived”)
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Outline
// ElevatorSimulationEvent.java
// Basic event packet holding Location object
package com.deitel.jhtp5.elevator.event;
ElevatorSimulat
ionEvent.java
// Deitel packages
import com.deitel.jhtp5.elevator.model.*;
public class ElevatorSimulationEvent {
Represents an event
in elevator simulation
// Location that generated ElevatorSimulationEvent
private Location location;
// source of generated ElevatorSimulationEvent
private Object source;
// ElevatorSimulationEvent constructor sets Location
public ElevatorSimulationEvent( Object source,
Location location )
{
setSource( source );
setLocation( location );
}
Line 8
Line 11
Location object reference
represents location where even
was generated Line 14
Object object reference represents
object that generated event
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// set ElevatorSimulationEvent Location
public void setLocation( Location eventLocation )
{
location = eventLocation;
}
Outline
ElevatorSimulat
ionEvent.java
// get ElevatorSimulationEvent Location
public Location getLocation()
{
return location;
}
// set ElevatorSimulationEvent source
private void setSource( Object eventSource )
{
source = eventSource;
}
// get ElevatorSimulationEvent source
public Object getSource()
{
return source;
}
}
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All rights reserved.
11.9 (Optional Case Study) Thinking About
Objects: Event Handling
• Objects send ElevatorSimulationEvent
– This may become confusing
• Door sends ElevatorSimulationEvent to Person
upon opening
• Elevator sends ElevatorSimulationEvent to Door
upon arrival
– Solution:
• Create several ElevatorSimulationEvent subclasses
– Each subclass better represents action
– e.g., BellEvent when Bell rings
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87
Fig. 11.26 Class diagram that models the generalization between
ElevatorSimulationEvent and its subclasses.
ElevatorSimulationEvent
BellEvent
DoorEvent
LightEvent
PersonMoveEvent
 2003 Prentice Hall, Inc. All rights reserved.
ButtonEvent
ElevatorMoveEvent
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Fig. 11.27 Triggering actions of the
ElevatorSimulationEvent subclass events
Event
BellEvent
Sent when (triggering action)
the Bell has rung
Sent by object of class
Bell
ButtonEvent
a Button has been pressed
a Button has been reset
a Door has opened
a Door has closed
a Light has turned on
a Light has turned off
a Person has been created
a Person has arrived at the Elevator
a Person has entered the Elevator
a Person has exited the Elevator
a Person has pressed a Button
a Person has exited the simulation
the Elevator has arrived at a Floor
the Elevator has departed from a Floor
Button
Button
Door
Door
Light
DoorEvent
LightEvent
PersonMoveEvent
ElevatorMoveEvent
Person
Elevator
Fig. 11.27 Triggering actions of the ElevatorSimulationEvent subclass events.
 2003 Prentice Hall, Inc. All rights reserved.
89
11.9 (Optional Case Study) Thinking About
Objects: Event Handling
• Event handling
– Similar to collaboration
– Object sends message (event) to objects
• However, receiving objects must be listening for event
– Called event listeners
– Listeners must register with sender to receive event
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90
11.9 (Optional Case Study) Thinking About
Objects: Event Handling
• Modify collaboration diagram of Fig. 7.19
– Incorporate event handling (Fig. 11.28)
– Three changes
• Include notes
– Explanatory remarks about UML graphics
– Represented as rectangles with corners “folded over”
• All interactions happen on first Floor
– Eliminates naming ambiguity
• Include events
– Elevator informs objects of action that has happened
• Elevator notifies object of arrival
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Fig. 11.28 Modified collaboration diagram for passengers entering
and exiting the Elevator on the first Floor
3.2.1 doorOpened( DoorEvent )
3.2 : openDoor( )
firstFloorDoor : Door
4.1.1 : resetButton( )
firstFloorButton : Button
4.2.1 : turnOnLight( )
: ElevatorShaft
4.1 : elevatorArrived(
ElevatorMoveEvent )
firstFloorLight: Light
4.2 : elevatorArrived( ElevatorMoveEvent )
4 : elevatorArrived( ElevatorMoveEvent )
waitingPassenger : Person
ridingPassenger : Person
: Elevator
3.2.1.1 : enterElevator( )
3.3.1 : exitElevator( )
2 : elevatorArrived(
ElevatorMoveEvent )
elevatorButton: Button
1.1: resetButton( )
 2003 Prentice Hall, Inc. All rights reserved.
: Bell
2.1: ringBell( )
3.3 : doorOpened( )
: ElevatorDoor
3.1: openDoor( Location )
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11.9 (Optional Case Study) Thinking About
Objects: Event Handling
• Event listeners
– Elevator sends ElevatorMoveEvent
• All event classes (in our simulation) have this structure
– Door must implement interface that “listens” for this event
– Door implements interface ElevatorMoveListener
• Method elevatorArrived
– Invoked when Elevator arrives
• Method elevatorDeparted
– Invoked when Elevator departs
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// ElevatorMoveEvent.java
// Indicates on which Floor the Elevator arrived or departed
package com.deitel.jhtp5.elevator.event;
// Deitel package
import com.deitel.jhtp5.elevator.model.*;
Outline
ElevatorMoveEve
nt.java
public class ElevatorMoveEvent extends ElevatorSimulationEvent {
// ElevatorMoveEvent constructor
public ElevatorMoveEvent( Object source, Location location )
{
super( source, location );
}
}
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All rights reserved.
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// ElevatorMoveListener.java
// Methods invoked when Elevator has either departed or arrived
package com.deitel.jhtp5.elevator.event;
public interface ElevatorMoveListener {
Outline
ElevatorMoveLis
tener.java
// invoked when Elevator has departed
public void elevatorDeparted( ElevatorMoveEvent moveEvent );
// invoked when Elevator has arrived
public void elevatorArrived( ElevatorMoveEvent moveEvent );
}
 2003 Prentice Hall, Inc.
All rights reserved.
11.9 (Optional Case Study) Thinking About
Objects: Event Handling
• Class diagram revisited
– Modify class diagram of Fig. 10.28 to include
• Signals (events)
– e.g., Elevator signals arrival to Light
• Self associations
– e.g., Light turns itself on and off
 2003 Prentice Hall, Inc. All rights reserved.
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Fig. 11.31 Class diagram of our simulator
(including event handling)
1
1
Light
ElevatorShaft
1
2
Opens /
Closes
1
Door
1
1
Signalsar
rival
Resets
1
Signals
arrival
1
1
1
1
Turns
on/off
2
Signals arrival
2
Button
1
Presses
1
Person
1
1
1
1
Informs of
opening
Opens/Closes
1
1
1
Elevator
ElevatorDoor
Signals
arrival
1
Signals
arrival
Rings
1
1
1
Signals to
move
1
Bell
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1
1
Occupies
Signals
arrival
2
1
Location
Floor
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