Home » openjdk-7 » javax » swing » [javadoc | source]

    1   /*
    2    * Copyright (c) 1999, 2000, Oracle and/or its affiliates. All rights reserved.
    3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
    4    *
    5    * This code is free software; you can redistribute it and/or modify it
    6    * under the terms of the GNU General Public License version 2 only, as
    7    * published by the Free Software Foundation.  Oracle designates this
    8    * particular file as subject to the "Classpath" exception as provided
    9    * by Oracle in the LICENSE file that accompanied this code.
   10    *
   11    * This code is distributed in the hope that it will be useful, but WITHOUT
   12    * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   13    * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   14    * version 2 for more details (a copy is included in the LICENSE file that
   15    * accompanied this code).
   16    *
   17    * You should have received a copy of the GNU General Public License version
   18    * 2 along with this work; if not, write to the Free Software Foundation,
   19    * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   20    *
   21    * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   22    * or visit www.oracle.com if you need additional information or have any
   23    * questions.
   24    */
   25   
   26   package javax.swing;
   27   
   28   import java.util;
   29   
   30   /**
   31    * The purpose of this class is to help clients support smooth focus
   32    * navigation through GUIs with text fields. Such GUIs often need
   33    * to ensure that the text entered by the user is valid (for example,
   34    * that it's in
   35    * the proper format) before allowing the user to navigate out of
   36    * the text field. To do this, clients create a subclass of
   37    * <code>InputVerifier</code> and, using <code>JComponent</code>'s
   38    * <code>setInputVerifier</code> method,
   39    * attach an instance of their subclass to the <code>JComponent</code> whose input they
   40    * want to validate. Before focus is transfered to another Swing component
   41    * that requests it, the input verifier's <code>shouldYieldFocus</code> method is
   42    * called.  Focus is transfered only if that method returns <code>true</code>.
   43    * <p>
   44    * The following example has two text fields, with the first one expecting
   45    * the string "pass" to be entered by the user. If that string is entered in
   46    * the first text field, then the user can advance to the second text field
   47    * either by clicking in it or by pressing TAB. However, if another string
   48    * is entered in the first text field, then the user will be unable to
   49    * transfer focus to the second text field.
   50    * <p>
   51    * <pre>
   52    * import java.awt.*;
   53    * import java.util.*;
   54    * import java.awt.event.*;
   55    * import javax.swing.*;
   56    *
   57    * // This program demonstrates the use of the Swing InputVerifier class.
   58    * // It creates two text fields; the first of the text fields expects the
   59    * // string "pass" as input, and will allow focus to advance out of it
   60    * // only after that string is typed in by the user.
   61    *
   62    * public class VerifierTest extends JFrame {
   63    *     public VerifierTest() {
   64    *         JTextField tf1 = new JTextField ("Type \"pass\" here");
   65    *         getContentPane().add (tf1, BorderLayout.NORTH);
   66    *         tf1.setInputVerifier(new PassVerifier());
   67    *
   68    *         JTextField tf2 = new JTextField ("TextField2");
   69    *         getContentPane().add (tf2, BorderLayout.SOUTH);
   70    *
   71    *         WindowListener l = new WindowAdapter() {
   72    *             public void windowClosing(WindowEvent e) {
   73    *                 System.exit(0);
   74    *             }
   75    *         };
   76    *         addWindowListener(l);
   77    *     }
   78    *
   79    *     class PassVerifier extends InputVerifier {
   80    *         public boolean verify(JComponent input) {
   81    *             JTextField tf = (JTextField) input;
   82    *             return "pass".equals(tf.getText());
   83    *         }
   84    *     }
   85    *
   86    *     public static void main(String[] args) {
   87    *         Frame f = new VerifierTest();
   88    *         f.pack();
   89    *         f.setVisible(true);
   90    *     }
   91    * }
   92    * </pre>
   93    *
   94    *  @since 1.3
   95    */
   96   
   97   
   98   public abstract class InputVerifier {
   99   
  100     /**
  101      * Checks whether the JComponent's input is valid. This method should
  102      * have no side effects. It returns a boolean indicating the status
  103      * of the argument's input.
  104      *
  105      * @param input the JComponent to verify
  106      * @return <code>true</code> when valid, <code>false</code> when invalid
  107      * @see JComponent#setInputVerifier
  108      * @see JComponent#getInputVerifier
  109      *
  110      */
  111   
  112     public abstract boolean verify(JComponent input);
  113   
  114   
  115     /**
  116      * Calls <code>verify(input)</code> to ensure that the input is valid.
  117      * This method can have side effects. In particular, this method
  118      * is called when the user attempts to advance focus out of the
  119      * argument component into another Swing component in this window.
  120      * If this method returns <code>true</code>, then the focus is transfered
  121      * normally; if it returns <code>false</code>, then the focus remains in
  122      * the argument component.
  123      *
  124      * @param input the JComponent to verify
  125      * @return <code>true</code> when valid, <code>false</code> when invalid
  126      * @see JComponent#setInputVerifier
  127      * @see JComponent#getInputVerifier
  128      *
  129      */
  130   
  131     public boolean shouldYieldFocus(JComponent input) {
  132       return verify(input);
  133     }
  134   
  135   }

Home » openjdk-7 » javax » swing » [javadoc | source]