You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
80 lines
2.3 KiB
Java
80 lines
2.3 KiB
Java
Simple Strings
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
* messing about with Java Strings
|
|
*/
|
|
public class SimpleStrings {
|
|
public static void main( String[] args ) {
|
|
// a string is a array of characters
|
|
char[] helloChars = {'h', 'e', 'l', 'l', 'o'};
|
|
String helloString = new String( helloChars );
|
|
System.out.println( helloString );
|
|
|
|
// best way to assign a string literal
|
|
helloString = "hello";
|
|
|
|
// no need to do this
|
|
helloString = new String( "hello" );
|
|
|
|
// an example
|
|
String barryWhite = "i love you all!";
|
|
System.out.println( barryWhite.length() ); // 15
|
|
System.out.println( barryWhite.charAt( 0 ) ); // i
|
|
System.out.println( barryWhite.startsWith( "i love" ) ); // true
|
|
System.out.println( barryWhite.endsWith( "all" ) ); // false
|
|
System.out.println( barryWhite.indexOf( 'l' ) ); // 2
|
|
System.out.println( barryWhite.indexOf( "you" ) ); // 7
|
|
System.out.println( barryWhite.substring( 7 ) ); // you all!
|
|
System.out.println( barryWhite.substring( 3, 8 ) ); // ove y
|
|
|
|
// String equality
|
|
String a = "hello";
|
|
String b = "world";
|
|
String c = new String( "hello" );
|
|
String d = a;
|
|
|
|
// == between Java objects is on reference equality
|
|
// equals() method is used to value equality
|
|
System.out.println( a == b ); // false
|
|
System.out.println( a == c ); // false
|
|
System.out.println( a.equals( c ) ); // true
|
|
System.out.println( a == d ); // true
|
|
|
|
// String are immutable
|
|
String noChange = "have i changed, not likely";
|
|
|
|
noChange.substring( 3 );
|
|
noChange.toLowerCase();
|
|
noChange.toUpperCase();
|
|
noChange.trim();
|
|
System.out.println( noChange ); // have i changed, not likely
|
|
|
|
// StringBuffer usage
|
|
StringBuffer buffer = new StringBuffer();
|
|
for( int i = 0; i < 10; i++ ) {
|
|
buffer.append( "say hello: " );
|
|
buffer.append( i );
|
|
buffer.append( "\n" );
|
|
}
|
|
|
|
System.out.println( buffer );
|
|
/**
|
|
* this outputs
|
|
* say hello: 0
|
|
* say hello: 1
|
|
* say hello: 2
|
|
* say hello: 3
|
|
* say hello: 4
|
|
* say hello: 5
|
|
* say hello: 6
|
|
* say hello: 7
|
|
* say hello: 8
|
|
* say hello: 9
|
|
*/
|
|
}
|
|
}
|