请使用 NetBeans 打开考生文件夹下的项目 Java_2 ,本题是完成 Radio 按钮实现的实例。要求进行调试后,程序结果如下: 由于 Java_2.java 文件不完整,请在注释行“ //***********Found**************** ”下一行语句的下划线地方填入正确内容,然后删除下划线,请勿删除注释行或其他已有语句内容。存盘时不得改变原有文件的文件名及存放目录。 import java.awt.*; import java.awt.event.*; import javax.swing.*; public class Java_2{ public static void main(String[] args){ RadioButtonFrame frame = new RadioButtonFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //*********Found********** ___________________; } } class RadioButtonFrame extends JFrame{ public RadioButtonFrame(){ setTitle("Radio按钮实例"); setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT); Container contentPane = getContentPane(); label = new JLabel("热烈庆祝Java程序语言开考三周年"); label.setForeground(Color.yellow); contentPane.setBackground(Color.red); label.setFont(new Font("黑体", Font.PLAIN, DEFAULT_SIZE)); contentPane.add(label, BorderLayout.CENTER); buttonPanel = new JPanel(); group = new ButtonGroup(); addRadioButton("小", 8); addRadioButton("中", 12); addRadioButton("大", 18); addRadioButton("特大", 30); contentPane.add(buttonPanel, BorderLayout.SOUTH); } public void addRadioButton(String name, final int size){ boolean selected = size == DEFAULT_SIZE; //*********Found********** JRadioButton button = new ____________________(name, selected); group.add(button); buttonPanel.add(button); ActionListener listener = new ActionListener(){ //*********Found********** public void actionPerformed(_____________________ evt){ label.setFont(new Font("黑体", Font.PLAIN, size)); } }; //*********Found********** button.addActionListener(__________________); } public static final int DEFAULT_WIDTH = 340; public static final int DEFAULT_HEIGHT = 200; private JPanel buttonPanel; private ButtonGroup group; private JLabel label; private static final int DEFAULT_SIZE = 12; }