5.5 JRadionButton类

当我们希望创建一个相斥的可切换组件组时我们可以使用JRadioButton。尽管由技术上来说，我们可以将一组JCheckBox组件放在一个ButtonGroup中，并且每次只有一个可以选中，但是他们看起来并不正确。至少由预定义的观感类型来看，JRadioButton与JCheckBox组件看起来是不同的，如图5-10所示。这种外观上的区别可以告诉终端用户可以期望组件的特定行为。

package net.ariel.ch05;

import java.awt.Container;
import java.awt.GridLayout;

import javax.swing.BorderFactory;
import javax.swing.ButtonGroup;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.border.Border;

public class RadioButtonUtils {

private RadioButtonUtils() {

}

public static Container createRadioButtonGrouping(String elements[], String title) {
JPanel panel = new JPanel(new GridLayout(0,1));

if(title != null) {
Border border = BorderFactory.createTitledBorder(title);
panel.setBorder(border);
}

ButtonGroup group = new ButtonGroup();
JRadioButton aRadioButton;

for(int i=0, n=elements.length; inew JRadioButton(elements[i]);
panel.add(aRadioButton);
group.add(aRadioButton);
}

return panel;
}
}
现在我们可以更为简单的创建组合了，如列表5-6中的示例程序所示。

/**
*
*/
package net.ariel.ch05;

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.EventQueue;

import javax.swing.JFrame;

/**
* @author mylxiaoyi
*
*/
public class GroupRadio {

private static final String sliceOptions[] = {
"4 slices", "8 slices", "12 slices", "16 slices"
};
private static final String crustOptions[] = {
"Sicilian", "Thin Crust", "Thick Crust", "Stuffed Crust"
};
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub

Runnable runner = new Runnable() {
public void run() {
JFrame frame = new JFrame("Grouping Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

Container sliceContainer = RadioButtonUtils.createRadioButtonGrouping(sliceOptions, "Slice Count");
Container crustContainer = RadioButtonUtils.createRadioButtonGrouping(crustOptions, "Crust Type");

frame.add(sliceContainer, BorderLayout.WEST);
frame.add(crustContainer, BorderLayout.EAST);

frame.setSize(300, 200);
frame.setVisible(true);
}
};
EventQueue.invokeLater(runner);
}

}

JRadioButton是由几方面构成的。类似于JToggleButton与JCheckBox，JRadioButton也使用一个ToggleButtonModel来表示其数据模型。他使用ButtonGroup通过AbstractButton来提供互斥的组合，并且用户界面委托是RadioButtonUI。

下面我们就来探讨如何使用JRadioButton的不同方同。

5.5.1 创建JRadioButton组件

与JCheckBox以及JToggleButton类似，JRadioButton有八个构造函数：

public JRadioButton()
JRadioButton aRadioButton = new JRadioButton();
 
public JRadioButton(Icon icon)
JRadioButton aRadioButton = new JRadioButton(new DiamondIcon(Color.CYAN, false));
aRadioButton.setSelectedIcon(new DiamondIcon(Color.BLUE, true));
 
public JRadioButton(Icon icon, boolean selected)
JRadioButton aRadioButton = new JRadioButton(new DiamondIcon(Color.CYAN, false),
  true);
aRadioButton.setSelectedIcon(new DiamondIcon(Color.BLUE, true));
 
public JRadioButton(String text)
JRadioButton aRadioButton = new JRadioButton("4 slices");
 
public JRadioButton(String text, boolean selected)
JRadioButton aRadioButton = new JRadioButton("8 slices", true);
 
public JRadioButton(String text, Icon icon)
JRadioButton aRadioButton = new JRadioButton("12 slices",
  new DiamondIcon(Color.CYAN, false));
aRadioButton.set