J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1999-2000 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any 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 | } |