maptest.java

来自「MapTest」· Java 代码 · 共 62 行

// Fig. 24.13 : MapTest.java
// Using a HashMap to store the number of words that
// begin with a given letter
import java.util.*;

public class MapTest {
   private static  String names[] = { "one", "two", "three",
                                  "four", "five", "six",
                                  "seven", "two", "ten", "four" };
                  
   public MapTest()
   {
      HashMap m = new HashMap();
      Integer i;

      for ( int k = 0; k < names.length; k++ ) {
         i = ( Integer ) m.get( new Character(
                                names[ k ].charAt( 0 ) ) );

         // if key is not in map then give it value one
         // otherwise increment its value by 1
         if ( i == null )
            m.put( new Character( names[ k ].charAt( 0 ) ),
                   new Integer( 1 ) );
         else
            m.put( new Character( names[ k ].charAt( 0 ) ),
                   new Integer( i.intValue() + 1 ) );
      }

      System.out.print( "\nnumber of words beginning with "
                        + "each letter:    " );
      printMap( m );
   }

   public void printMap( Map mapRef )
   {
      System.out.println( mapRef.toString() );
      System.out.println( "size: " + mapRef.size() );
      System.out.println( "isEmpty: " + mapRef.isEmpty() );         
   }                                                    

   public static void main( String args[] )
   {
      new MapTest();
   }                                           
}

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