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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
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* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
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*/
package javax.swing;
import java.util.*;
/**
* The purpose of this class is to help clients support smooth focus
* navigation through GUIs with text fields. Such GUIs often need
* to ensure that the text entered by the user is valid (for example,
* that it's in
* the proper format) before allowing the user to navigate out of
* the text field. To do this, clients create a subclass of
* <code>InputVerifier</code> and, using <code>JComponent</code>'s
* <code>setInputVerifier</code> method,
* attach an instance of their subclass to the <code>JComponent</code> whose input they
* want to validate. Before focus is transfered to another Swing component
* that requests it, the input verifier's <code>shouldYieldFocus</code> method is
* called. Focus is transfered only if that method returns <code>true</code>.
* <p>
* The following example has two text fields, with the first one expecting
* the string "pass" to be entered by the user. If that string is entered in
* the first text field, then the user can advance to the second text field
* either by clicking in it or by pressing TAB. However, if another string
* is entered in the first text field, then the user will be unable to
* transfer focus to the second text field.
* <p>
* <pre>
* import java.awt.*;
* import java.util.*;
* import java.awt.event.*;
* import javax.swing.*;
*
* // This program demonstrates the use of the Swing InputVerifier class.
* // It creates two text fields; the first of the text fields expects the
* // string "pass" as input, and will allow focus to advance out of it
* // only after that string is typed in by the user.
*
* public class VerifierTest extends JFrame {
* public VerifierTest() {
* JTextField tf1 = new JTextField ("Type \"pass\" here");
* getContentPane().add (tf1, BorderLayout.NORTH);
* tf1.setInputVerifier(new PassVerifier());
*
* JTextField tf2 = new JTextField ("TextField2");
* getContentPane().add (tf2, BorderLayout.SOUTH);
*
* WindowListener l = new WindowAdapter() {
* public void windowClosing(WindowEvent e) {
* System.exit(0);
* }
* };
* addWindowListener(l);
* }
*
* class PassVerifier extends InputVerifier {
* public boolean verify(JComponent input) {
* JTextField tf = (JTextField) input;
* return "pass".equals(tf.getText());
* }
* }
*
* public static void main(String[] args) {
* Frame f = new VerifierTest();
* f.pack();
* f.setVisible(true);
* }
* }
* </pre>
*
* @since 1.3
*/
public abstract class InputVerifier {
/**
* Checks whether the JComponent's input is valid. This method should
* have no side effects. It returns a boolean indicating the status
* of the argument's input.
*
* @param input the JComponent to verify
* @return <code>true</code> when valid, <code>false</code> when invalid
* @see JComponent#setInputVerifier
* @see JComponent#getInputVerifier
*
*/
public abstract boolean verify(JComponent input);
/**
* Calls <code>verify(input)</code> to ensure that the input is valid.
* This method can have side effects. In particular, this method
* is called when the user attempts to advance focus out of the
* argument component into another Swing component in this window.
* If this method returns <code>true</code>, then the focus is transfered
* normally; if it returns <code>false</code>, then the focus remains in
* the argument component.
*
* @param input the JComponent to verify
* @return <code>true</code> when valid, <code>false</code> when invalid
* @see JComponent#setInputVerifier
* @see JComponent#getInputVerifier
*
*/
public boolean shouldYieldFocus(JComponent input) {
return verify(input);
}
}