exercise13_2.java

一款用java编写的小型数据库管理系统

import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
import javax.swing.border.*;
public class Exercise13_2 extends JFrame{
	private double a;
	private JTextField jt1 = new JTextField(10);
	private JTextField jt2 = new JTextField(10);
	private JTextField jt3 = new JTextField(10);
	public Exercise13_2(){
        jt3.setEditable(false);
		JPanel jp1=new JPanel();
		JPanel jp2=new JPanel();
		JButton jbAdd=new JButton("Add");
		jbAdd.setMnemonic('A');
		JButton jbSub=new JButton("Subtract");
		jbSub.setMnemonic('S');
		JButton jbMul =new JButton("Multiply");
		jbMul.setMnemonic('M');
		JButton jbDiv=new JButton("Divide");
		jbDiv.setMnemonic('D');
		jp2.setLayout(new FlowLayout());
		jp2.add(jbAdd);
		jp2.add(jbSub);
		jp2.add(jbMul);
		jp2.add(jbDiv);

		add(jp2,BorderLayout.SOUTH);
		JLabel jl1=new JLabel();
		JLabel jl2=new JLabel();
		JLabel jl3=new JLabel();


		jl1.setText("Number 1");
		jl2.setText("Number 2");
		jl3.setText("Result");
		jp1.setLayout(new FlowLayout());
		jp1.add(jl1);
		jp1.add(jt1);
		jp1.add(jl2);
		jp1.add(jt2);
		jp1.add(jl3);
		jp1.add(jt3);


		add(jp1,BorderLayout.NORTH);

		jbAdd.addActionListener(new ActionListener() {
	       public void actionPerformed(ActionEvent e) {

	         a=(Double.parseDouble(jt1.getText())+Double.parseDouble(jt2.getText()));
             jt3.setText(""+a);
	       }
    });
    jbSub.addActionListener(new ActionListener() {
		       public void actionPerformed(ActionEvent e) {
		         a=(Double.parseDouble(jt1.getText())-Double.parseDouble(jt2.getText()));
	             jt3.setText(""+a);
		       }
    });
    jbMul.addActionListener(new ActionListener() {
		       public void actionPerformed(ActionEvent e) {
		         a=(Double.parseDouble(jt1.getText())*Double.parseDouble(jt2.getText()));
	             jt3.setText(""+a);
		       }
    });
    jbDiv.addActionListener(new ActionListener() {
		       public void actionPerformed(ActionEvent e) {
		         a=(Double.parseDouble(jt1.getText())/Double.parseDouble(jt2.getText()));
	             jt3.setText(""+a);
		       }
    });

	}
	public static void main(String[]a){
		Exercise13_2 frame=new Exercise13_2();
		frame.setSize(550,100);
		frame.setLocationRelativeTo(null);
	    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	    frame.setVisible(true);
	}
}