JAVA实现简单计算器

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package Demo5;

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

class MyPanel extends JPanel implements ActionListener {
	
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	JTextArea text = new JTextArea();
	String str[]={"7","8","9","+","4","5","6","-","1","2","3","*","0",".","=","/"};
	JButton btn[] = new JButton[str.length];



	public MyPanel() {
		setLayout(new GridLayout(4,4,5,5));
		init();
	}
	
	public void init() {
		
		for(int i=0;i<str.length;i++){
			btn[i]=new JButton(str[i]);
			btn[i].addActionListener(this);
			add(btn[i]);
			
		}

	}
	
	public void actionPerformed(ActionEvent e) {
		JButton b = (JButton)e.getSource();
		if(b != btn[14]) {
			text.append(b.getText());
		}
		else {
			String str = text.getText();
			if(str.indexOf("*")!=-1) {
				if(str.indexOf(".")!=-1) {
					String[] arr = str.split("\*");
					double a0 = Double.parseDouble(arr[0]);
					double b0 = Double.parseDouble(arr[1]);
					text.setText(String.valueOf(a0*b0));
				}
				else {
					String[] arr = str.split("\*");
					int a1 = Integer.parseInt(arr[0]);
					int b1 = Integer.parseInt(arr[1]);
					text.setText(String.valueOf(a1*b1));
				}					
			}
			if(str.indexOf("/")!=-1) {
				if(str.indexOf(".")!=-1) {
					String[] arr = str.split("\/");
					double a2 = Double.parseDouble(arr[0]);
					double b2 = Double.parseDouble(arr[1]);
					text.setText(String.valueOf(a2/b2));
				}
				else {
					String[] arr = str.split("\/");
					int a3 = Integer.parseInt(arr[0]);
					int b3 = Integer.parseInt(arr[1]);
					text.setText(String.valueOf(a3/b3));
				}
			}
			if(str.indexOf("+")!=-1) {
				if(str.indexOf(".")!=-1) {
					String[] arr = str.split("\+");
					double a4 = Double.parseDouble(arr[0]);
					double b4 = Double.parseDouble(arr[1]);
					System.out.print(a4+b4);
					text.setText(String.valueOf(a4+b4));
				}
				else {
					String[] arr = str.split("\+");
					int a5 = Integer.parseInt(arr[0]);
					int b5 = Integer.parseInt(arr[1]);
					text.setText(String.valueOf(a5+b5));
				}
			}
			if(str.indexOf("-")!=-1) {
				if(str.indexOf(".")!=-1) {
					String[] arr = str.split("-");
					double a6 = Double.parseDouble(arr[0]);
					double b6 = Double.parseDouble(arr[1]);
					text.setText(String.valueOf(a6-b6));
				}
				else {
					String[] arr = str.split("-");
					int a7 = Integer.parseInt(arr[0]);
					int b7 = Integer.parseInt(arr[1]);
					text.setText(String.valueOf(a7-b7));
				}
			}
		}
	}
}





class MyFrame extends JFrame{
	
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	MyPanel pane = new MyPanel();
	JTextArea text = pane.text;
	public MyFrame() {
		add(text,"North");
		add(pane,"Center");
		setBounds(200,200,300,300);
		setVisible(true);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	}
	
	
}

public class Demo3 {
	public static void main(String[] args) {
		MyFrame frame = new MyFrame();
	}
}