在Java Swing中取消选择RadioButtons

Question

显示一组JRadioButtons时,最初没有选择它们(除非您以编程方式强制执行).即使在用户已选择按钮之后,我也希望能够将按钮重新置于该状态,即,不应选择任何按钮.

但是,使用通常的嫌疑人无法提供所需的效果: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时它确实有效 - 不幸的是,后者是JRadioButtons互斥的必需品.

此外,使用setSelected(ButtonModel,boolean) - javax.swing.ButtonGroup的方法不能做我想要的.

我已经整理了一个小程序来演示效果:两个单选按钮和一个JButton.单击JButton应取消选择单选按钮,以使窗口看起来与第一次弹出时完全一样.

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);
    }
}

任何人的想法？谢谢!

Answer 1

你可以做到buttonGroup.clearSelection().

但是这种方法仅在Java 6之后才可用.

Answer 2

该类的Javadoc ButtonGroup本身提供了一些关于如何实现这一点的提示:

从类的API doc ButtonGroup:
最初,组中的所有按钮都是未选中的.选择任何按钮后,组中始终会选择一个按钮.无法以编程方式将按钮设置为"关闭",以便清除按钮组.要给出"未选择"的外观,请向该组添加一个不可见的单选按钮,然后以编程方式选择该按钮以关闭所有显示的单选按钮.