stringcompare.java

我在学习JAVA的讲义

// This program demonstrates the methods equals, 
// equalsIgnoreCase, compareTo, and regionMatches 
// of the String class.
import javax.swing.JOptionPane;

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

      s1 = new String( "hello" );
      s2 = new String( "good bye" );
      s3 = new String( "Happy Birthday" );
      s4 = new String( "happy birthday" );

      output = "s1 = " + s1 + "\ns2 = " + s2 +
               "\ns3 = " + s3 + "\ns4 = " + s4 + "\n\n";

      // test for equality
      if ( s1.equals( "hello" ) )
         output += "s1 equals \"hello\"\n";
      else
         output += "s1 does not equal \"hello\"\n"; 

      // test for equality with ==
      if ( s1 == "hello" )
         output += "s1 equals \"hello\"\n";
      else
         output += "s1 does not equal \"hello\"\n";

      // test for equality--ignore case
      if ( s3.equalsIgnoreCase( s4 ) )
         output += "s3 equals s4\n";
      else
         output += "s3 does not equal s4\n";

      // test compareTo
      output +=
         "\ns1.compareTo( s2 ) is " + s1.compareTo( s2 ) +
         "\ns2.compareTo( s1 ) is " + s2.compareTo( s1 ) +
         "\ns1.compareTo( s1 ) is " + s1.compareTo( s1 ) +
         "\ns3.compareTo( s4 ) is " + s3.compareTo( s4 ) +
         "\ns4.compareTo( s3 ) is " + s4.compareTo( s3 ) +
         "\n\n";

      // test regionMatches (case sensitive)
      if ( s3.regionMatches( 0, s4, 0, 5 ) )
         output += "First 5 characters of s3 and s4 match\n";
      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";

      JOptionPane.showMessageDialog( null, output,
         "Demonstrating String Class Constructors",
         JOptionPane.INFORMATION_MESSAGE );

      System.exit( 0 );
   }
}