Java Swing JRadioButton

Java Swing教程 - Java Swing JRadioButton

JRadioButton有兩種狀態(tài):選中和未選中。當(dāng)我們需要用戶進(jìn)行單選時(shí)使用一組JRadioButtons。

我們可以使用一個(gè)Action對(duì)象，一個(gè)字符串標(biāo)簽，圖標(biāo)和布爾標(biāo)志，以指示其是否被選擇默認(rèn)創(chuàng)建JRadioButton。

創(chuàng)建沒(méi)有標(biāo)簽和沒(méi)有圖像的JRadioButton

JRadioButton rb1  = new JRadioButton();

創(chuàng)建JRadioButton，文本為“我的選擇"

JRadioButton rb2  = new JRadioButton("My Choice");

創(chuàng)建JRadioButton，文本為“我的選擇"并默認(rèn)選擇

JRadioButton rb3  = new JRadioButton("My Choice", true);

要選擇/取消選擇JRadioButton，請(qǐng)調(diào)用setSelected()方法。

要檢查是否被選中，請(qǐng)使用它們的isSelected()方法。

以下代碼顯示如何使用這些方法:

tb3.setSelected(true);      // Select tb3
boolean b1  = tb3.isSelected(); 
// will store true in b1 
tb3.setSelected(false);    // Unselect tb3
boolean b2  = tb3.isSelected(); // will store false in b2

如果選擇是互斥的，我們必須在按鈕組中分組所有選擇。ButtonGroup類的一個(gè)實(shí)例表示一個(gè)按鈕組。

我們可以通過(guò)使用它的add()和remove()方法分別向按鈕組添加和刪除JRadioButton。

最初，按鈕組的所有成員都未選中。

要形成一個(gè)按鈕組，我們需要將所有互斥選擇組件添加到ButtonGroup類的一個(gè)對(duì)象。 我們不會(huì)向容器添加ButtonGroup對(duì)象。

我們必須向容器中添加所有選擇的組件。

下面的代碼顯示了一組三個(gè)相互排斥的JRadioButton。

import java.awt.BorderLayout;
import java.awt.Container;
/*  w ww.  j  a va 2 s .  c  o  m*/
import javax.swing.Box;
import javax.swing.ButtonGroup;
import javax.swing.JFrame;
import javax.swing.JRadioButton;

public class Main extends JFrame {
  ButtonGroup genderGroup = new ButtonGroup();
  JRadioButton genderMale = new JRadioButton("Male");
  JRadioButton genderFemale = new JRadioButton("Female");
  JRadioButton genderUnknown = new JRadioButton("Unknown");

  public Main() {
    this.setDefaultCloseOperation(EXIT_ON_CLOSE);

    genderGroup.add(genderMale);
    genderGroup.add(genderFemale);
    genderGroup.add(genderUnknown);

    Box b1 = Box.createVerticalBox();
    b1.add(genderMale);
    b1.add(genderFemale);
    b1.add(genderUnknown);

    Container contentPane = this.getContentPane();
    contentPane.add(b1, BorderLayout.CENTER);
  }

  public static void main(String[] args) {
    Main bf = new Main();
    bf.pack();
    bf.setVisible(true);
  }
}

動(dòng)作偵聽(tīng)器

下面的代碼顯示了如何使用ActionListener監(jiān)聽(tīng)JRadioButton事件。

import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
// ww w .j  av  a  2s.  co m
import javax.swing.AbstractButton;
import javax.swing.ButtonGroup;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;

public class Main {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Grouping Example");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JPanel panel = new JPanel(new GridLayout(0, 1));

    ButtonGroup group = new ButtonGroup();
    JRadioButton aRadioButton = new JRadioButton("A");
    JRadioButton bRadioButton = new JRadioButton("B");

    ActionListener sliceActionListener = new ActionListener() {
      public void actionPerformed(ActionEvent actionEvent) {
        AbstractButton aButton = (AbstractButton) actionEvent.getSource();
        System.out.println("Selected: " + aButton.getText());
      }
    };

    panel.add(aRadioButton);
    group.add(aRadioButton);
    panel.add(bRadioButton);
    group.add(bRadioButton);

    aRadioButton.addActionListener(sliceActionListener);
    bRadioButton.addActionListener(sliceActionListener);


    frame.add(panel);
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}

更改偵聽(tīng)器

下面的代碼顯示了如何使用ChangeListener監(jiān)聽(tīng)JRadioButton事件。

它告訴你當(dāng)所選單選按鈕被布防，按下，選擇或釋放時(shí)。

import java.awt.GridLayout;
//w w  w . ja  v  a 2s .c  o m
import javax.swing.AbstractButton;
import javax.swing.ButtonGroup;
import javax.swing.ButtonModel;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class Main {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Grouping Example");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JPanel panel = new JPanel(new GridLayout(0, 1));

    ButtonGroup group = new ButtonGroup();
    JRadioButton aRadioButton = new JRadioButton("A");
    JRadioButton bRadioButton = new JRadioButton("B");

    ChangeListener changeListener = new ChangeListener() {
      public void stateChanged(ChangeEvent changEvent) {
        AbstractButton aButton = (AbstractButton)changEvent.getSource();
        ButtonModel aModel = aButton.getModel();
        boolean armed = aModel.isArmed();
        boolean pressed = aModel.isPressed();
        boolean selected = aModel.isSelected();
        System.out.println("Changed: " + armed + "/" + pressed + "/" +
          selected);
      }
    };

    panel.add(aRadioButton);
    group.add(aRadioButton);
    panel.add(bRadioButton);
    group.add(bRadioButton);

    aRadioButton.addChangeListener(changeListener);
    bRadioButton.addChangeListener(changeListener);

    frame.add(panel);
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
  
}

項(xiàng)目偵聽(tīng)器

下面的代碼顯示了如何使用ItemListener監(jiān)聽(tīng)JRadioButton事件。

import java.awt.GridLayout;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
//  w  ww . j a  v  a2  s . co  m
import javax.swing.AbstractButton;
import javax.swing.ButtonGroup;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;

public class Main {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Grouping Example");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JPanel panel = new JPanel(new GridLayout(0, 1));

    ButtonGroup group = new ButtonGroup();
    JRadioButton aRadioButton = new JRadioButton("A");
    JRadioButton bRadioButton = new JRadioButton("B");

    ItemListener itemListener = new ItemListener() {
      String lastSelected;
      public void itemStateChanged(ItemEvent itemEvent) {
        AbstractButton aButton = (AbstractButton)itemEvent.getSource();
        int state = itemEvent.getStateChange();
        String label = aButton.getText();
        String msgStart;
        if (state == ItemEvent.SELECTED) {
          if (label.equals(lastSelected)) {
            msgStart = "Reselected -> ";
          }  else {
           msgStart = "Selected -> ";
          }
          lastSelected = label;
        }  else {
          msgStart = "Deselected -> ";
        }
        System.out.println(msgStart + label);
      }
    };

    panel.add(aRadioButton);
    group.add(aRadioButton);
    panel.add(bRadioButton);
    group.add(bRadioButton);

    aRadioButton.addItemListener(itemListener);
    bRadioButton.addItemListener(itemListener);

    frame.add(panel);
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
  
}