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136 lines
4.0 KiB
136 lines
4.0 KiB
/*
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* Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*
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*
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*/
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package javax.swing;
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import java.util.*;
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/**
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* The purpose of this class is to help clients support smooth focus
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* navigation through GUIs with text fields. Such GUIs often need
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* to ensure that the text entered by the user is valid (for example,
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* that it's in
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* the proper format) before allowing the user to navigate out of
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* the text field. To do this, clients create a subclass of
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* <code>InputVerifier</code> and, using <code>JComponent</code>'s
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* <code>setInputVerifier</code> method,
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* attach an instance of their subclass to the <code>JComponent</code> whose input they
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* want to validate. Before focus is transfered to another Swing component
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* that requests it, the input verifier's <code>shouldYieldFocus</code> method is
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* called. Focus is transfered only if that method returns <code>true</code>.
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* <p>
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* The following example has two text fields, with the first one expecting
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* the string "pass" to be entered by the user. If that string is entered in
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* the first text field, then the user can advance to the second text field
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* either by clicking in it or by pressing TAB. However, if another string
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* is entered in the first text field, then the user will be unable to
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* transfer focus to the second text field.
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*
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* <pre>
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* import java.awt.*;
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* import java.util.*;
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* import java.awt.event.*;
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* import javax.swing.*;
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*
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* // This program demonstrates the use of the Swing InputVerifier class.
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* // It creates two text fields; the first of the text fields expects the
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* // string "pass" as input, and will allow focus to advance out of it
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* // only after that string is typed in by the user.
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*
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* public class VerifierTest extends JFrame {
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* public VerifierTest() {
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* JTextField tf1 = new JTextField ("Type \"pass\" here");
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* getContentPane().add (tf1, BorderLayout.NORTH);
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* tf1.setInputVerifier(new PassVerifier());
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*
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* JTextField tf2 = new JTextField ("TextField2");
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* getContentPane().add (tf2, BorderLayout.SOUTH);
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*
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* WindowListener l = new WindowAdapter() {
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* public void windowClosing(WindowEvent e) {
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* System.exit(0);
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* }
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* };
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* addWindowListener(l);
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* }
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*
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* class PassVerifier extends InputVerifier {
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* public boolean verify(JComponent input) {
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* JTextField tf = (JTextField) input;
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* return "pass".equals(tf.getText());
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* }
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* }
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*
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* public static void main(String[] args) {
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* Frame f = new VerifierTest();
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* f.pack();
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* f.setVisible(true);
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* }
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* }
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* </pre>
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*
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* @since 1.3
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*/
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public abstract class InputVerifier {
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/**
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* Checks whether the JComponent's input is valid. This method should
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* have no side effects. It returns a boolean indicating the status
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* of the argument's input.
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*
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* @param input the JComponent to verify
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* @return <code>true</code> when valid, <code>false</code> when invalid
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* @see JComponent#setInputVerifier
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* @see JComponent#getInputVerifier
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*
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*/
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public abstract boolean verify(JComponent input);
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/**
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* Calls <code>verify(input)</code> to ensure that the input is valid.
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* This method can have side effects. In particular, this method
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* is called when the user attempts to advance focus out of the
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* argument component into another Swing component in this window.
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* If this method returns <code>true</code>, then the focus is transfered
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* normally; if it returns <code>false</code>, then the focus remains in
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* the argument component.
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*
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* @param input the JComponent to verify
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* @return <code>true</code> when valid, <code>false</code> when invalid
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* @see JComponent#setInputVerifier
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* @see JComponent#getInputVerifier
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*
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*/
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public boolean shouldYieldFocus(JComponent input) {
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return verify(input);
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}
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}
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