import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class Demo extends JFrame {
	JPanel jp1 = new JPanel();
	JPanel jp2 = new JPanel();
	JPanel jp3 = new JPanel();
	JButton bt1 = new JButton("+");
	JButton bt2 = new JButton("-");
	JButton bt3 = new JButton("*");
	JButton bt4 = new JButton("/");
	JTextField jf1 = new JTextField();
	JTextField jf2 = new JTextField();
	JTextField jf3 = new JTextField("我來顯示");
	JLabel jl1 = new JLabel("運算結果:");
	JLabel jl2 = new JLabel("+");

	public Demo() {
		setBounds(100,100,200,200);
		setTitle("簡易Windows計算器");
		jf1.setColumns(6);
		jf2.setColumns(6);
		jf3.setColumns(12);
		jp1.setLayout(new GridLayout(2,2));         
		jp1.add(bt1);
		jp1.add(bt2);
		jp1.add(bt3);
		jp1.add(bt4);
		jp2.setLayout(new FlowLayout());
		jp2.add(jl1);
		jp2.add(jf3);
		jp3.setLayout(new FlowLayout());               
		jp3.add(jf1);
		jp3.add(jl2);
		jp3.add(jf2);
		setLayout(new BorderLayout());        //控制佈局
		add("South",jp1);
		add("North",jp3);            
		add("Center",jp2);
		bt1.addActionListener(new ActionListener() {          //按鈕'+'加監聽
			
			@Override
			public void actionPerformed(ActionEvent arg0) {
				jl2.setText("+");                  //設定顯示的符號
				String x1 = jf1.getText();          //賦值鍵入的資料
				String x2 = jf2.getText();
				int s1 = Integer.parseInt(x1);      //轉換為整數
				int s2 = Integer.parseInt(x2);
				int s3 = s1 + s2;                   //運算
				jf3.setText(s3+"");               //中間的文字框顯示結果
				
			}
		});
		bt2.addActionListener(new ActionListener() {        //同上
			
			@Override
			public void actionPerformed(ActionEvent arg0) {
				jl2.setText("-");
				String x1 = jf1.getText();
				String x2 = jf2.getText();
				int s1 = Integer.parseInt(x1);
				int s2 = Integer.parseInt(x2);
				int s3 = s1 - s2;
				jf3.setText(s3+"");
				
			}
		});
		bt3.addActionListener(new ActionListener() {
			
			@Override
			public void actionPerformed(ActionEvent arg0) {
				jl2.setText("*");
				String x1 = jf1.getText();
				String x2 = jf2.getText();
				int s1 = Integer.parseInt(x1);
				int s2 = Integer.parseInt(x2);
				int s3 = s1 * s2;
				jf3.setText(s3+"");
				
			}
		});
		bt4.addActionListener(new ActionListener() {
			
			@Override
			public void actionPerformed(ActionEvent arg0) {
				jl2.setText("/");
				String x1 = jf1.getText();
				String x2 = jf2.getText();
				int s1 = Integer.parseInt(x1);
				int s2 = Integer.parseInt(x2);
				int s3 = s1 / s2;
				jf3.setText(s3+"");				
			}
		});
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setVisible(true);
	}

	public static void main(String[] args) {
		new Demo();
	}
}