labeltext.java

北京大学出版社的

package examples.classes;

/** A Java class for text labels of arbitrary
  * length limit
  */
public class LabelText {

   private static final int MAX_TEXT = 20;
   private String label;

   /** Class constructor
     * @param inputText The text to be assigned
     *                  to the label
     */
   public LabelText( String inputText ) {
      System.out.println( 
         "Creating a LabelText object" );
      if ( inputText.length() <= MAX_TEXT ) {
         label = inputText;
      } else {
         System.err.println(
            "Input label text is too long!");
         //NOTE: next line extracts 20 chars at
         //      index 0 to 19
         label = inputText.substring( 0, MAX_TEXT );  
      }
   }

   /** Provide the string representation of the object
     * @return The label text
     */
   public String toString() {
       return label;
   }

   /** Method to output the contents of the object
     * to <code>System.out</code>
     */
   public void print() {
      System.out.println( label );
   }

   /** Test method for the class
     * @param args Not used
     */
   public static void main( String[] args ) {
      LabelText a = new LabelText( "Capital Losses" );
      LabelText b
         = new LabelText( "Really Big Capital Gains" );
      a.print();
      System.out.println( a );
      b.print();
      System.out.println( b );
   }
}