e4_11.java

来自「java 初学者学习实例」· Java 代码 · 共 76 行

// Fig. 11.3: StringCompare.java
// String methods equals, equalsIgnoreCase, compareTo and regionMatches.
import javax.swing.JOptionPane;
// StringCompare
public class E4_11{

   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";

      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"; 

      // test for equality with ==
      if ( s1 == "hello" )  // false; they are not the same object
         output += "s1 equals \"hello\"\n";
      else
         output += "s1 does not equal \"hello\"\n";

      // 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 ) 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,
         "String comparisons", JOptionPane.INFORMATION_MESSAGE );

      System.exit( 0 );
   }

} // end class StringCompare

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