简易计算器怎么写用JAVA

Question

 

Answer 1

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class 简单计算器  extends JFrame implements ActionListener{
	JTextField txtNum1,txtNum2,txtNum3;
	JComboBox<String> cbOpr;
	String opr[] = {"+","-","*","/"};
	JButton btnCalc;
	public 简单计算器() {
		super("简单计算器");
		
		txtNum1 = new JTextField(6);
		cbOpr = new JComboBox<String>(opr);
		txtNum2 = new JTextField(6);
		txtNum3 = new JTextField(6);
		btnCalc = new JButton("=");
		JPanel northPane = new JPanel(new FlowLayout());
		northPane.add(txtNum1);
		northPane.add(cbOpr);
		northPane.add(txtNum2);
		northPane.add(btnCalc);
		northPane.add(txtNum3);
		txtNum3.setEnabled(false);
		add(northPane);
		btnCalc.addActionListener(this);
		this.pack();
		setVisible(true);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setLocationRelativeTo(null);
		
	}
	@Override
	public void actionPerformed(ActionEvent e) {
		
		try {
			double num1 = Double.parseDouble(txtNum1.getText());
			double num2 = Double.parseDouble(txtNum2.getText());
			int index = cbOpr.getSelectedIndex();
			switch(index) {
			case 0:
				txtNum3.setText((num1+num2)+"");
				break;
			case 1:
				txtNum3.setText((num1-num2)+"");
				break;
			case 2:
				txtNum3.setText((num1*num2)+"");
				break;
			case 3:
				txtNum3.setText((num1/num2)+"");
				break;
			}
		}catch(Exception ex){
			System.out.println("出错了"+ex.getMessage());
		}
	}
	public static void main(String[] args) {
		new 简单计算器();
	}
}