--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/javax/swing/InputVerifier.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,135 @@
+/*
+ * Copyright 1999-2000 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun 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.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+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);
+  }
+
+}