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* accompanied this code).
*
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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
* {@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.
*
* @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 {@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.
*
* @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 {@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);
}
}