JOptionPane - 检查用户输入并防止在满足条件之前关闭

Question

请有人告诉我是否有一种方便的方法可以防止JOptionPane 在单击“确定”时关闭，除非满足用户输入字段的条件？

还是我别无选择，只能使用JFrame？

到目前为止我的验证逻辑。似乎不起作用，因为这些按钮出于某种原因可以一次性点击...

final JDialog dialog3 = new JDialog(OmniGUI.getFrame(), "Create new Node - id:" + newNodeID);
dialog3.setContentPane(theOPane);
dialog3.setDefaultCloseOperation(JDialog.DO_NOTHING_ON_CLOSE);

theOPane.addPropertyChangeListener(new PropertyChangeListener(){
   public void propertyChange(PropertyChangeEvent e) {

       if(e.getSource() == theOPane){
           String val = (String) ((JOptionPane) e.getSource()).getValue();

           if(val=="Create"){
               System.out.println("Checking content");                      

               if(!valid){
                   System.out.println("closing the window");    

                   dialog3.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
                   dialog3.removeAll();
                   dialog3.dispatchEvent(new WindowEvent(dialog3, WindowEvent.WINDOW_CLOSING));
               }

           }
       }
   }    
});

    dialog3.setLocation(p);
    dialog3.pack();
    dialog3.setVisible(true);

Answer 1

您可以创建自己的自定义JDialog 以在关闭或继续之前检查用户输入等。请参阅此链接：

Stopping Automatic Dialog Closing

默认情况下，当用户单击 JOptionPane 创建的按钮时， 对话框关闭。但是如果你想在之前检查用户的答案怎么办 关闭对话框？在这种情况下，您必须实现自己的属性 更改侦听器，以便当用户单击按钮时，对话框执行 不会自动关闭。

这是我做的一个例子：

如果您输入错误/无文本并单击“输入”，将显示验证消息：

如果您单击 X 关闭对话框或单击取消，也会显示验证消息：

如果输入正确的文本（在本例中为“David”）并单击输入，则会显示一条消息并退出 JDialog：

CustomDialog.java：

import java.awt.*;
import java.awt.event.*;
import java.beans.*;
import javax.swing.JDialog;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;

class CustomDialog extends JDialog
        implements ActionListener,
        PropertyChangeListener {

    private String typedText = null;
    private JTextField textField;
    private String magicWord;
    private JOptionPane optionPane;
    private String btnString1 = "Enter";
    private String btnString2 = "Cancel";

    /**
     * Returns null if the typed string was invalid; otherwise, returns the
     * string as the user entered it.
     */
    public String getValidatedText() {
        return typedText;
    }

    /**
     * Creates the reusable dialog.
     */
    public CustomDialog(Frame aFrame, String aWord) {
        super(aFrame, true);

        magicWord = aWord.toUpperCase();
        setTitle("Quiz");

        textField = new JTextField(10);

        //Create an array of the text and components to be displayed.
        String msgString1 = "What was Dr. SEUSS's real last name?";
        String msgString2 = "(The answer is \"" + magicWord
                + "\".)";
        Object[] array = {msgString1, msgString2, textField};

        //Create an array specifying the number of dialog buttons
        //and their text.
        Object[] options = {btnString1, btnString2};

        //Create the JOptionPane.
        optionPane = new JOptionPane(array,
                JOptionPane.QUESTION_MESSAGE,
                JOptionPane.YES_NO_OPTION,
                null,
                options,
                options[0]);

        //Make this dialog display it.
        setContentPane(optionPane);

        //Handle window closing correctly.
        setDefaultCloseOperation(DISPOSE_ON_CLOSE);

        //Ensure the text field always gets the first focus.
        addComponentListener(new ComponentAdapter() {
            @Override
            public void componentShown(ComponentEvent ce) {
                textField.requestFocusInWindow();
            }
        });

        //Register an event handler that puts the text into the option pane.
        textField.addActionListener(this);

        //Register an event handler that reacts to option pane state changes.
        optionPane.addPropertyChangeListener(this);
        pack();
    }

    /**
     * This method handles events for the text field.
     */
    @Override
    public void actionPerformed(ActionEvent e) {
        optionPane.setValue(btnString1);
    }

    /**
     * This method reacts to state changes in the option pane.
     */
    @Override
    public void propertyChange(PropertyChangeEvent e) {
        String prop = e.getPropertyName();

        if (isVisible()
                && (e.getSource() == optionPane)
                && (JOptionPane.VALUE_PROPERTY.equals(prop)
                || JOptionPane.INPUT_VALUE_PROPERTY.equals(prop))) {
            Object value = optionPane.getValue();

            if (value == JOptionPane.UNINITIALIZED_VALUE) {
                //ignore reset
                return;
            }

            //Reset the JOptionPane's value.
            //If you don't do this, then if the user
            //presses the same button next time, no
            //property change event will be fired.
            optionPane.setValue(
                    JOptionPane.UNINITIALIZED_VALUE);

            if (btnString1.equals(value)) {
                typedText = textField.getText();
                String ucText = typedText.toUpperCase();
                if (magicWord.equals(ucText)) {
                    JOptionPane.showMessageDialog(this, "Correct answer given");
                    exit();
                } else {
                    //text was invalid
                    textField.selectAll();
                    JOptionPane.showMessageDialog(this,
                            "Sorry, \"" + typedText + "\" "
                            + "isn't a valid response.\n"
                            + "Please enter "
                            + magicWord + ".",
                            "Try again",
                            JOptionPane.ERROR_MESSAGE);
                    typedText = null;
                    textField.requestFocusInWindow();
                }
            } else { //user closed dialog or clicked cancel
                JOptionPane.showMessageDialog(this, "It's OK.  "
                        + "We won't force you to type "
                        + magicWord + ".");
                typedText = null;
                exit();
            }
        }
    }

    /**
     * This method clears the dialog and hides it.
     */
    public void exit() {
        dispose();
    }

    public static void main(String... args) {
        //create JDialog and components on EDT
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new CustomDialog(null, "David").setVisible(true);
            }
        });
    }
}

Answer 2

关于Stop Automatic Dialog Closing 的一件事是，它只有在您想阻止关闭或验证然后关闭时才有帮助...基于该教程中的示例代码的解决方案，我无法让它验证并保持打开状态如果验证失败。

回想起来，我认为我第一次尝试失败的原因可能是因为它使用了 JOptionPanel.createDialog() （而不是示例代码所做的）。也许让 JOptionPanel 创建它自己的 JDialog 在事件处理的工作方式中设置了一些“背景”依赖项......嗯。无论如何，我现在得到了我想要的：David Kroucamp 的代码对我非常有用。

我发布我的解决方案是因为它处理 PropertyChangeEvents 的方式与 David 不同，因此它可能对某些人有用。您会看到大部分代码与他的相同（感谢 David）

此类检查文件是否存在并让用户提供新名称或取消。它在构造函数中使用一些参数来验证用户的输入。验证是 if(!Files.exists(rootPathArg.resolve(input))) { // close the dialog }

class GetPathNameDialog extends JDialog implements ActionListener, PropertyChangeListener {

    /**
     * contains the users input
     */
    private JTextField textField;
    /**
     * the option pane that holds all fields and controls in this dialog
     */
    private JOptionPane optionPane;
    /**
     * label for the left button that represents "OK"
     */
    private String button1Str;
    /**
     * label for the right button that represents "Cancel"
     */
    private String button2Str;
    /**
     * path containing the named entity to be renamed.
     */
    private Path rootPath;

    /**
     * Creates the reusable dialog.
     */
    /**
     * Creates the dialog, panel and all GUI components, sets up listeners.
     *
     * @param rootPath the path where the file or folder we are renaming lives
     * @param initialText the initial text to display in the text field (i.e. current name)
     * @param title title of the JDialog itself
     * @param textFieldWidth number of columns in the JTextField that will contain the file/folder name
     * @param promptStr the propmt to display in the panel
     * @param button1Str the label for the "OK" button
     * @param button2Str the label for the "Cancel" button
     */
    public GetPathNameDialog(Path rootPath, String initialText, String title, int textFieldWidth, String promptStr, String button1Str, String button2Str) {

        super((Frame) null, true);

        // init class variables
        this.rootPath = rootPath;
        this.button1Str = button1Str;
        this.button2Str = button2Str;

        setTitle(title);

        textField = new JTextField(textFieldWidth);
        textField.setText(initialText);

        //Create an array of the text and components to be displayed.
        Object[] array = {promptStr, textField};

        //Create an array specifying the number of dialog buttons
        //and their text.
        Object[] options = {button1Str, button2Str};

        //Create the JOptionPane.
        optionPane = new JOptionPane(
                array,
                JOptionPane.QUESTION_MESSAGE,
                JOptionPane.YES_NO_OPTION,
                null,
                options,
                options[0]);

        //Make this dialog display it.
        setContentPane(optionPane);

        //Handle window closing correctly.
        setDefaultCloseOperation(DISPOSE_ON_CLOSE);

        //Ensure the text field always gets the first focus.
        addComponentListener(new ComponentAdapter() {
            @Override
            public void componentShown(ComponentEvent ce) {
                textField.requestFocusInWindow();
            }
        });

        // Register an event handler that puts the text into the option pane INPUT_VALUE_PROPERTY
        textField.addActionListener(this);

        // Register an event handler that reacts to option pane state changes.
        optionPane.addPropertyChangeListener(this);

        // tell this dialog to display close to the current mouse pointer
        setLocation(MouseInfo.getPointerInfo().getLocation());
        pack();
    }

    /**
     * This method handles events for the text field.
     */
    @Override
    public void actionPerformed(ActionEvent e) {
        // this will fire a INPUT_VALUE_PROPERTY PropertyChangeEvent... takes the user input to the validaton code in the property handler
        optionPane.setInputValue(textField.getText());
    }

    /**
     * This method reacts to property changes.
     */
    @Override
    public void propertyChange(PropertyChangeEvent e) {

        String prop = e.getPropertyName();

        if (isVisible() && (e.getSource() == optionPane)) {

            // the VALUE_PROPERTY is not the same as the INPUT_VALUE_PROPERTY. we make use of the INPUT_VALUE_PROPERTY to carry our data
            // but the JOptionPane uses the VALUE_PROPERTY for other stuff
            if (JOptionPane.VALUE_PROPERTY.equals(prop)) {
                // newValues delivered by VALUE_PROPERTY PropertyChangeEvent can be the actual labels of the button clicked,
                // that's sooo counter-intuitive to me, but it's how we know which button got clicked
                if (button1Str.equals(e.getNewValue())) {
                    // "OK" functionality...
                    // ...this will fire the event that takes the user input to the validation code
                    optionPane.setInputValue(textField.getText());
                } else if (button2Str.equals(e.getNewValue())) {
                    // "CANCEL" functionality
                    optionPane.setInputValue(null);
                    exit();
                }

            } else if (JOptionPane.INPUT_VALUE_PROPERTY.equals(prop)) {

                Object value = optionPane.getInputValue();

                // null or empty strings in the text field (ie in the INPUT_VALUE_PROPERTY) are ignored
                if (null != value && ((String) value).length() > 0) {
                    // here is the validation code
                    if (Files.exists(rootPath.resolve(textField.getText()))) {
                        // already exists, tell user
                        JOptionPane.showMessageDialog(this,
                                "Sorry, " + rootPath.resolve(textField.getText()).toString() + " already exists.\n\n Please enter another name.",
                                "OK",
                                JOptionPane.ERROR_MESSAGE);
                        // Make sure PropertyChangeEvent will fire next time...
                        // ...PropertyChangeEvents don't fire in setInputValue(newVal)...
                        // ...if newVal is equal to the current value, but if the user clicks...
                        // ...button 1 or hits enter in the text field without changing his text,...
                        // ...we still want to fire another event...
                        // ...so we reset the property without changing the text in the textField
                        optionPane.setInputValue(null);
                    } else {
                        // does not exist.. we are keeping the users input...
                        // ... it gets delivered to the user in getInputValue()
                        exit();
                    }
                }
            }
        }
    }

    /**
     * returns the users's validated input. Validated means !Files.exists(rootPath.resolve(input)).
     *
     * @return the text entered by the user, UNINITIALIZED_VALUE if the user X closed, null the user canceled
     */
    public Object getInputValue() {
        return optionPane.getInputValue();
    }

    /**
     * closes the dialog and triggers the return from setVisible()
     */
    public void exit() {
        dispose();
    }
}

调用它的代码是：

    GetPathNameDialog tempD = new GetPathNameDialog(
                        someFolderPath,
                        "theFileNameThatMustBeChanged.txt",
                        "Change File Name",
                        50,
                        "someFolderPath already contains a file named theFileNameThatMustBeChanged.txt." + ".\n\nPlease enter a different file name:",
                        "Copy the file with the new name", "Do not copy the file");
    tempD.setVisible(true);

    Object inputObj = tempD.getInputValue();
    String input = (inputObj == JOptionPane.UNINITIALIZED_VALUE || null == inputObj ? "" : (String) inputObj);

    if (input.length() > 0) {
        // we now have a new file name. go ahead and do the copy or rename or whatever...
    }