Java/Data Type/String equal

Check string for equality

   <source lang="java">

public class Main {

 public static void main(String[] args) {
   String s1 = "Hello World";
   String s2 = new String("Hello World");
   if (s1.equals(s2)) {
     System.out.println("String is equal");
   } else {
     System.out.println("String is unequal");
   }
   if (s1 == s2) {
     System.out.println("String is equal");
   } else {
     System.out.println("String is unequal");
   }
 }

}

 </source>
   
  
 
  

Determine whether a string is a palindrome?

   <source lang="java">

public class Main {

 static boolean isPalindrome(String text) {
   System.out.println("Original text = " + text);
   String reverse = new StringBuilder(text).reverse().toString();
   System.out.println("Reverse text  = " + reverse);
   return text.equalsIgnoreCase(reverse);
 }
 public static void main(String[] args) {
   String text = "Sator Arepo Tenet Opera Rotas";
   System.out.println("Is Palindrom: " + isPalindrome(text));
 }

}

 </source>
   
  
 
  

String: equal

   <source lang="java">

/*

* Copyright (c) Ian F. Darwin, http://www.darwinsys.ru/, 1996-2002.
* All rights reserved. Software written by Ian F. Darwin and others.
* $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS""
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
* 
* Java, the Duke mascot, and all variants of Sun"s Java "steaming coffee
* cup" logo are trademarks of Sun Microsystems. Sun"s, and James Gosling"s,
* pioneering role in inventing and promulgating (and standardizing) the Java 
* language and environment is gratefully acknowledged.
* 
* The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
* inventing predecessor languages C and C++ is also gratefully acknowledged.
*/

public class Equality {

 public static void main(String[] args) { 
   new Equality().run();
 }
 public void run() {
   String x = "hello";
   String y = "hello";
 
   // Assuming Equality uses a String constant, this prints true,true
   compare(x, y);
   // A "new String" is uniquely created, so this prints false, true
   compare(x, new String(y));
   // The substring operator creates a new String, prints false, true
   compare(x, "hello world".substring(0, 5));
   // The intern() operator returns a string from the pool of unique
   // strings, so this should print true, true.
   compare(x, new String(x).intern());
 }
 public void compare(String s1, String s2) {
   System.out.print("==:       ");
   System.out.println(s1 == s2);
   System.out.println(".equals():" + s1.equals(s2));
   System.out.println(); 
 }

}

 </source>