/*
* Copyright (c) 1999, 2016, Oracle and/or its affiliates. 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. 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.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package javax.swing;
import java.util.*;
This class provides the validation mechanism for Swing components. GUIs often need to ensure that the components are in a valid state before allowing the user to navigate the input focus. To do this, clients create a subclass of InputVerifier and, using JComponent's setInputVerifier method, attach an instance of their subclass to the JComponent which is the source of the focus transfer operation. The InputVerifier also provides the possibility to validate against the target of the focus transfer which may reject the focus. Before focus is transferred from the source Swing component to the target Swing component, the input verifier's shouldYieldFocus(source, target) method is called. Focus is transferred only if that method returns true.
The following example has two text fields, with the first one expecting
the string "pass" to be entered by the user. If either that string is entered
in the first text field or the second text field contains "accept" string,
then the user can advance focus to the second text field by clicking in it or
by pressing TAB.
However, if another string is entered in the first text field and the second
text field does not contain "accept", then the user will be unable to
transfer focus to the second text field.
import java.awt.*;
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 to the second text
// field if either that string is typed in by the user or the second
// field contains "accept" string.
public class VerifierTest extends JFrame {
public VerifierTest() {
JTextField field1 = new JTextField("Type \"pass\" here");
JTextField field2 = new JTextField("or \"accept\" here");
getContentPane().add(field1, BorderLayout.NORTH);
getContentPane().add(field2, BorderLayout.SOUTH);
field.setInputVerifier(new InputVerifier() {
public boolean verify(JComponent input) {
return "pass".equals(((JTextField) input).getText());
}
public boolean verifyTarget(JComponent input) {
return "accept".equals(((JTextField) input).getText());
}
public boolean shouldYieldFocus(JComponent source,
JComponent target) {
return verify(source) || verifyTarget(target);
}
});
pack();
setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(VerifierTest::new);
}
}
Since: 1.3
/**
* This class provides the validation mechanism for Swing components. GUIs often
* need to ensure that the components are in a valid state before allowing the
* user to navigate the input focus. To do this, clients create a subclass of
* {@code InputVerifier} and, using {@code JComponent}'s
* {@code setInputVerifier} method, attach an instance of their subclass to
* the {@code JComponent} which is the source of the focus transfer operation.
* The {@code InputVerifier} also provides the possibility to validate against
* the target of the focus transfer which may reject the focus.
* Before focus is transferred from the source Swing component to the target
* Swing component, the input verifier's
* {@code shouldYieldFocus(source, target)} method is called. Focus is
* transferred only if that method returns
* {@code true}.
* <p>
* The following example has two text fields, with the first one expecting
* the string "pass" to be entered by the user. If either that string is entered
* in the first text field or the second text field contains "accept" string,
* then the user can advance focus to the second text field by clicking in it or
* by pressing TAB.
* However, if another string is entered in the first text field and the second
* text field does not contain "accept", then the user will be unable to
* transfer focus to the second text field.
*
* <pre>
* import java.awt.*;
* 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 to the second text
* // field if either that string is typed in by the user or the second
* // field contains "accept" string.
*
* public class VerifierTest extends JFrame {
*
* public VerifierTest() {
* JTextField field1 = new JTextField("Type \"pass\" here");
* JTextField field2 = new JTextField("or \"accept\" here");
* getContentPane().add(field1, BorderLayout.NORTH);
* getContentPane().add(field2, BorderLayout.SOUTH);
*
* field.setInputVerifier(new InputVerifier() {
* public boolean verify(JComponent input) {
* return "pass".equals(((JTextField) input).getText());
* }
*
* public boolean verifyTarget(JComponent input) {
* return "accept".equals(((JTextField) input).getText());
* }
*
* public boolean shouldYieldFocus(JComponent source,
* JComponent target) {
* return verify(source) || verifyTarget(target);
* }
* });
*
* pack();
* setVisible(true);
* }
*
* public static void main(String[] args) {
* SwingUtilities.invokeLater(VerifierTest::new);
* }
* }
* </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.
Params: - input – the JComponent to verify
See Also: Returns: true when valid, false when invalid
/**
* 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} when valid, {@code false} when invalid
* @see JComponent#setInputVerifier
* @see JComponent#getInputVerifier
*/
public abstract boolean verify(JComponent input);
Calls verify(input) 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 true, then the focus is transferred normally; if it returns false, then the focus remains in the argument component. Params: - input – the JComponent to verify
See Also: Returns: true when valid, false when invalidDeprecated: use shouldYieldFocus(JComponent, JComponent) instead.
/**
* Calls {@code verify(input)} 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}, then the focus is transferred
* normally; if it returns {@code false}, then the focus remains in
* the argument component.
*
* @param input the JComponent to verify
* @return {@code true} when valid, {@code false} when invalid
* @see JComponent#setInputVerifier
* @see JComponent#getInputVerifier
*
* @deprecated use {@link #shouldYieldFocus(JComponent, JComponent)}
* instead.
*/
@Deprecated(since = "9")
public boolean shouldYieldFocus(JComponent input) {
return verify(input);
}
Checks whether the target JComponent that will be receiving the focus
is ready to accept it. This method should be over-ridden only if it is
necessary to validate the target of the focus transfer.
This method should have no side effects. It returns a boolean
indicating the status of the argument's input.
Params: - target – the target JComponent to verify
See Also: Implementation Requirements: By default this method returns true. Returns: true when valid, false when invalidSince: 9
/**
* Checks whether the target JComponent that will be receiving the focus
* is ready to accept it. This method should be over-ridden only if it is
* necessary to validate the target of the focus transfer.
* This method should have no side effects. It returns a boolean
* indicating the status of the argument's input.
*
* @implSpec By default this method returns {@code true}.
*
* @param target the target JComponent to verify
* @return {@code true} when valid, {@code false} when invalid
* @see JComponent#setInputVerifier
* @see JComponent#getInputVerifier
* @since 9
*/
public boolean verifyTarget(JComponent target) {
return true;
}
Is called by Swing if this InputVerifier is assigned to the source Swing component to check whether the requested focus transfer from the source to target is allowed. This method can have side effects. If this method returns true, then the focus is transferred normally; if it returns false, then the focus remains in the first argument component. Params: - source – the source JComponent of the focus transfer
- target – the target JComponent of the focus transfer
See Also: Implementation Requirements: The basic implementation of this method returns the conjunction of results obtained from verify(input) and verifyTarget(input) to ensure that both the source and the target components are in valid state. Returns: true when valid, false when invalidSince: 9
/**
* Is called by Swing if this {@code InputVerifier} is assigned to the
* {@code source} Swing component to check whether the requested focus
* transfer from the {@code source} to {@code target} is allowed.
* This method can have side effects.
* If this method returns {@code true}, then the focus is transferred
* normally; if it returns {@code false}, then the focus remains in
* the first argument component.
*
* @implSpec The basic implementation of this method returns the conjunction
* of results obtained from {@code verify(input)} and
* {@code verifyTarget(input)} to ensure that both the source and the target
* components are in valid state.
*
* @param source the source JComponent of the focus transfer
* @param target the target JComponent of the focus transfer
* @return {@code true} when valid, {@code false} when invalid
* @see JComponent#setInputVerifier
* @see JComponent#getInputVerifier
* @since 9
*/
public boolean shouldYieldFocus(JComponent source, JComponent target) {
return shouldYieldFocus(source) && verifyTarget(target);
}
}