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| 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 | } | ||