Java第二次作业第四题

文本行输入学生姓名，下来框选择课程名称，文本行输入课程成绩；点击“录入”按钮，相关信息显示在文本区；点击“统计”按钮，将所有录入的成绩的平均成绩显示在另一个文本行中。

package naizi;

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

public class UserJFrame extends JFrame implements ActionListener
{
private JTextField text_name,text_avescore,text_score;
private JComboBox combobox_course;
private JButton button_add,button_statistics;
private JTextArea text_user;
private int sum=0,count=0;

public UserJFrame(){
	this.setSize(360,200);
	this.setLocation(300,240);
	this.getContentPane().setLayout(new GridLayout(1,2,5,5));//网格布局 

	text_user = new JTextArea();
	this.getContentPane().add(text_user);

	JPanel panel = new JPanel(new GridLayout(6,1,1,1)); //网格布局
	this.getContentPane().add(panel);  

	text_name = new JTextField("姓名");
	panel.add(text_name);

	Object course[]={"Java", "C++"};
	combobox_course = new JComboBox(course);
	panel.add(combobox_course);

	text_score = new JTextField("0");
	panel.add(text_score);

	button_add = new JButton("添加");
	button_add.addActionListener(this);   //注册监听事件
	panel.add(button_add);

	text_avescore = new JTextField("平均成绩");
	panel.add(text_avescore);

	button_statistics = new JButton("统计");
	button_statistics.addActionListener(this);    //注册监听事件;
	panel.add(button_statistics);
	this.setVisible(true);//显示界面

}

public void actionPerformed(ActionEvent e){    //单击事件处理方法
	if (e.getSource()== button_add){   //判断事件源
		String aline="";
		aline = text_name.getText();
		aline += ", "+combobox_course.getSelectedItem();
		aline += ", "+text_score.getText();
		text_user.append(aline+"\n");  //追加到文本区
//		text_user.setText(aline);  //追加到文本区
		sum=sum+Integer.valueOf(text_score.getText());//计算总分
		count++;
		text_score.setText("0");
	}
	if (e.getSource() == button_statistics){
		text_avescore.setText(Integer.toString(sum/count));
	}//设置统计成绩

}
public static void  main(String [] args){
    new UserJFrame();//运行程序窗体
}
}

运行结果如图：