在Java Swing中取消选择单选按钮

Question

当显示一组JRadioButton时，最初不会选择任何一个（除非您以编程方式强制执行此操作）。我希望即使在用户已经选择一个按钮之后，也可以将按钮放回该状态，即，不应选择任何按钮。

但是，使用通常的嫌疑人并不能达到预期的效果：在每个按钮上调用’setSelected（false）’不起作用。有趣的是，当按钮没有放入ButtonGroup时，它
确实可以 工作-不幸的是，对于JRadioButton来说，后者是互斥的。

另外，使用setSelected（ButtonModel，boolean）-javax.swing.ButtonGroup的方法不能满足我的要求。

我编写了一个小程序来演示效果：两个单选按钮和一个JButton。单击JButton应该取消选择单选按钮，以使窗口看起来与第一次弹出时完全相同。

import java.awt.Container;
import java.awt.GridLayout;
import java.awt.event.*;
import javax.swing.*;

/**
 * This class creates two radio buttons and a JButton. Initially, none
 * of the radio buttons is selected. Clicking on the JButton should
 * always return the radio buttons into that initial state, i.e.,
 * should disable both radio buttons.
 */
public class RadioTest implements ActionListener {
    /* create two radio buttons and a group */
    private JRadioButton button1 = new JRadioButton("button1");
    private JRadioButton button2 = new JRadioButton("button2");
    private ButtonGroup group = new ButtonGroup();

    /* clicking this button should unselect both button1 and button2 */
    private JButton unselectRadio = new JButton("Unselect radio buttons.");

    /* In the constructor, set up the group and event listening */
    public RadioTest() {
        /* put the radio buttons in a group so they become mutually
         * exclusive -- without this, unselecting actually works! */
        group.add(button1);
        group.add(button2);

        /* listen to clicks on 'unselectRadio' button */
        unselectRadio.addActionListener(this);
    }

    /* called when 'unselectRadio' is clicked */
    public void actionPerformed(ActionEvent e) {
        /* variant1: disable both buttons directly.
         * ...doesn't work */
        button1.setSelected(false);
        button2.setSelected(false);

        /* variant2: disable the selection via the button group.
         * ...doesn't work either */
        group.setSelected(group.getSelection(), false);
    }

    /* Test: create a JFrame which displays the two radio buttons and
     * the unselect-button */
    public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        RadioTest test = new RadioTest();

        Container contentPane = frame.getContentPane();
        contentPane.setLayout(new GridLayout(3,1));
        contentPane.add(test.button1);
        contentPane.add(test.button2);
        contentPane.add(test.unselectRadio);

        frame.setSize(400, 400);
        frame.setVisible(true);
    }
}

有任何想法吗？谢谢！

Answer 1

你可以做的buttonGroup.clearSelection()。

但是此方法仅自Java 6起可用。