// Fig. 10.11: StringIntern.java
// This program demonstrates the intern method
// of the String class.
import javax.swing.*;

public class StringIntern {
   public static void main( String args[] )
   {
      String s1, s2, s3, s4, output;

      s1 = new String( "hello" );
      s2 = new String( "hello" );

      // Test strings to determine if they are the same
      // String object in memory.
      if ( s1 == s2 )
         output =
            "s1 and s2 are the same object in memory";
      else
         output =
            "s1 and s2 are not the same object in memory";

      // Test strings for equality of contents
      if ( s1.equals( s2 ) )
         output += "\ns1 and s2 are equal";
      else
         output += "\ns1 and s2 are not equal";

      // Use String intern method to get a unique copy of
      // "hello" referred to by both s3 and s4.
      s3 = s1.intern();
      s4 = s2.intern();

      // Test strings to determine if they are the same
      // String object in memory.
      if ( s3 == s4 )
         output +=
            "\ns3 and s4 are the same object in memory";
      else
         output +=
            "\ns3 and s4 are not the same object in memory";

      // Determine if s1 and s3 refer to the same object
      if ( s1 == s3 )
         output +=
            "\ns1 and s3 are the same object in memory";
      else
         output +=
            "\ns1 and s3 are not the same object in memory";

      // Determine if s2 and s4 refer to the same object
      if ( s2 == s4 )
         output +=
            "\ns2 and s4 are the same object in memory";
      else
         output +=
            "\ns2 and s4 are not the same object in memory";

      // Determine if s1 and s4 refer to the same object
      if ( s1 == s4 )
         output +=
            "\ns1 and s4 are the same object in memory";
      else
         output +=
            "\ns1 and s4 are not the same object in memory";

      JOptionPane.showMessageDialog( null, output,
         "Demonstrating String Method intern",
         JOptionPane.INFORMATION_MESSAGE );

      System.exit( 0 );
   }
}

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 * (C) Copyright 1999 by Deitel & Associates, Inc. and Prentice Hall.     *
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