java 作业——简单计算器

要求：

1、参照Windows计算器功能，实现加、减、乘、除运算；
2、声明为按钮数组；
3、对0~9数字操作，采用相同的算法；
4、解决除数为零的问题；
5、具有清除一个数字、全部清除、开平方和平方功能。
6、计算结果保留4位小数。
7、界面缩放时，所有组件同步缩放，保持界面整体风格不变。

calculator函数：

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

public class calculator extends JPanel implements ActionListener {
		
	//声明按钮
	private JButton numJButton[][] = new JButton[5][4];
	//为初始化按钮做准备
	String name[][] = {{"√x","x²","←","＋"},
			{"7","8","9","－"},
			{"4","5","6","×"},
			{"1","2","3","÷"},
			{".","0","del","="}};
	
	private JTextField text = new JTextField();//声明文本框用于显示数据
	private JPanel temp[] = new JPanel[5];
	private String num = "",num2 = "";//两个待运算的数
	private int flag = 0;//全局标志变量
	
	public calculator() {
		
		this.setLayout(new GridLayout(6, 1));//先设置成六行一列的网格布局
        this.add(text);						//将文本框至于第一整行
        text.setEditable(false);			//设置文本框为不可编辑
        
        for(int i = 0;i < 5;i++)			//剩下的五行每一行四列，整体看就是一行文本框和五行按钮
        	temp[i] = new JPanel(new GridLayout(1,4));
        
		//按钮初始化
		for(int i=0;i<5;i++) {
			for(int j=0;j<4;j++) {
			numJButton[i][j] = new JButton(name[i][j]);
			numJButton[i][j].addActionListener(this);
			temp[i].add(numJButton[i][j]);
			}
		}
		
		//添加面板
		for(int i = 0;i < 5;i++)
        	this.add(temp[i]);
		
		this.setVisible(true);
	}

	//设置监听器
	@Override
	public void actionPerformed(ActionEvent e) {
		// 触发数字按钮
		//1~9的按钮
		for (int i = 1; i <=3 ; i++) {
			for (int j = 0; j <=2; j++) {
				if(e.getSource() == numJButton[i][j]) {
					if(flag==0) {
							/*
							 *e.getActionCommand()用来获得按钮显示的字符串
							 *numJButton[i][j].getLabel()也可以
							 */
							num = num + e.getActionCommand();
							text.setText(num);
	    			}
	    			else if(flag==-1){
	    				flag = 0;
	    				num = num + e.getActionCommand();
	    				text.setText(num);
	    			}
	    			else{
	    				num2 = num2+e.getActionCommand();
	    				text.setText(num2);
	    			}
				}	
			}
		}
		//0按钮，因为存储位置没有和其他数字的连在一起，所以单拿出来
		if(e.getSource() == numJButton[4][1])
		{
			num = num + e.getActionCommand();
			text.setText(num);
		}
		
		//触发加减乘除按钮，按钮顺序就是加减乘除
		for(int i=0;i<=3;i++) {
			if(e.getSource()==numJButton[i][3])
			{
				flag = i+1;
				text.setText(e.getActionCommand());
			}
		}
		
		//触发小数点按钮
		if(e.getSource()==numJButton[4][0])
    	{
    		if(flag==0 ||flag==-1) {
    			if(num.indexOf('.')==-1) {
    				flag = 0;
					num = num +".";
					text.setText(num);
    			}
			}
			else
			{
				if(num2.indexOf('.')==-1) {
					num2 = num2 +".";
					text.setText(num2);
    			}
			}
    	}
		
		//清空当前所有字符
		if(e.getSource()==numJButton[4][2]) 
    	{
    		if(flag==0 || flag == -1) {
	    		num = "";
	    		flag = -1;
	    		text.setText(num);
    		}
    		else
    		{
    			num2 = "";
	    		text.setText(num2);
    		}
    	}
		
		//根据标记的不同每次分情况清空一个字符
		if(e.getSource()==numJButton[0][2])
    	{
    		if((flag==0 || flag==-1)&&num.length()>0) {
    			flag = 0;
    			num = num.substring(0, num.length()-1);
    			if(num=="")
    				num = "0";
    			text.setText(num);
    		}
    		if(flag!=0 &&flag!=-1&&num2.length()>0) {
    			num2 = num2.substring(0, num2.length()-1);
    			if(num2=="")
    				num2 = "0";
    			text.setText(num2);
    		}
    	}
		
		//平方运算
		if(e.getSource()==numJButton[0][1]) 
    	{
    		double rlt;
    		if(flag == 0 ||flag == -1)
    		{
    			if(flag==-1)	flag = 0;
    			rlt = Double.parseDouble(num);
    			num = String.format("%.4f", rlt*rlt);
    		}
    		else
    			rlt = Double.parseDouble(num2);
    		rlt = rlt*rlt;
			text.setText(String.format("%.4f", rlt));
    	}
		
		//开方运算
		if(e.getSource()==numJButton[0][0])
    	{
    		double rlt=0;
    		if(flag == 0 ||flag == -1)
    		{
    			if(flag==-1)	flag = 0;
    			rlt = Math.sqrt(Double.parseDouble(num));
    			num = String.format("%.4f", rlt);
    		}
    		else
    		{
    			rlt = Math.sqrt(Double.parseDouble(num2));
    			num2 = String.format("%.4f", rlt);
    		}
    		text.setText(String.format("%.4f", rlt));
    	}
		
		int mark = 0;
		//触发了等号 进行求值运算
		if(e.getSource()==numJButton[4][3]) 
    	{
    		if(flag!=-1 && flag!=0) {
	    		double n1 = Double.parseDouble(num);
	    		double n2 = Double.parseDouble(num2);
	    		double result = 0;
	    		if(flag==1)
	    			result = n1+n2;
	    		else if(flag==2)
	    			result = n1-n2;
	    		else if(flag==3)
	    			result = n1*n2;
	    		else if(flag==4) {
	    			try {//处理除数为0的操作
	    				if(n2==0)
	    					throw new Exception();
	    				else
	    					result = n1/n2;
	    			}
	    			catch (Exception e1) {
						text.setText("0不能做除数");
						mark = 1;
					}
	    		}
	    		//除数不为0，或者进行的是其他操作时进行的操作
	    		flag = -1;
	    		num2 = "";
	    		if(mark!=1) {//除数不为0
	    			num = String.format("%.4f", result);
	    			text.setText(num);
	    		}
	    		else//除数为0
	    		{
	    			flag = 0;
	    			num = "0";
	    		}
    		} 
    	}
	}
}

test:

import javax.swing.JFrame;

public class test extends JFrame {

	 public test(calculator c)
	    {
	        super("计算器");
	        this.setBounds(300,400,400,400);
	        this.getContentPane().add(c);
	        this.setVisible(true);
	    }
	    public static void main(String[] args) {
	        new test(new calculator());
	    }
}

运行是这个样子