Question

用Java设计一个简单的计算器。

设计一个简单的计算器，能够对两个数据进行“加、减、乘、除”运算。要求：合理应用布局设计，注重界面美观、友好，要求处理NumberFormatException异常。

Answer 1

无聊写了个，修复了下Bug：

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JTextField;

public class Calculate extends JFrame implements ActionListener {

    private static final long serialVersionUID = 1L;

    private JButton plus, reduce, multiply, divice, reset;
    private JTextField one, two, result;
    private boolean device_falg = false;

    private final int width = 400, height = 300;

    public Calculate() {
        super("修改密码");
        this.setLayout(null);
        this.setSize(width, height);
        init();
        Layout();
    }

    public void init() {
        plus = new JButton("加   ");
        reduce = new JButton("减    ");
        multiply = new JButton("乘   ");
        divice = new JButton("除    ");
        reset = new JButton("清空");
        one = new JTextField();
        two = new JTextField();
        result = new JTextField();
    }

    public void Layout() {
        this.add(new JLabel("第一个数")).setBounds(20, 10, 60, 80);
        this.add(one).setBounds(100, 38, 100, 25);
        this.add(new JLabel("第二个数")).setBounds(20, 40, 60, 80);
        this.add(two).setBounds(100, 70, 100, 25);
        this.add(new JLabel("结果")).setBounds(20, 85, 60, 80);
        this.add(result).setBounds(100, 110, 100, 25);

        this.add(plus).setBounds(70, 170, 80, 25);
        this.add(reduce).setBounds(200, 170, 80, 25);
        this.add(multiply).setBounds(70, 200, 80, 25);
        this.add(divice).setBounds(200, 200, 80, 25);

        this.add(reset).setBounds(300, 220, 80, 25);

        plus.addActionListener(this);
        reduce.addActionListener(this);
        multiply.addActionListener(this);
        divice.addActionListener(this);
        reset.addActionListener(this);

        this.setVisible(true);
        this.setDefaultCloseOperation(DISPOSE_ON_CLOSE);
    }

    public boolean Format() {
        boolean FLAG = false;
        boolean flag = false;
        String one = this.one.getText().toString().trim();
        String two = this.two.getText().toString().trim();

        if (one == null || one.equals("") || two == null || two.equals("")) {
            JOptionPane.showMessageDialog(getParent(), "请输入完整信息!");
            FLAG = false;
            flag = true;
        }

        boolean boll_1 = one.matches("[\\d]{1,100}");
        boolean boll_2 = two.matches("[\\d]{1,100}");
        boolean boll_3 = one.matches("[\\d]{1,100}+[.]+[\\d]{1,100}");
        boolean boll_4 = two.matches("[\\d]{1,100}+[.]+[\\d]{1,100}");
        if (flag) {
            return false;
        }
        if ((boll_1 && boll_2) || (boll_3 && boll_4) || (boll_1 && boll_4)
                || (boll_3 && boll_2)) {
            FLAG = true;
        } else {
            JOptionPane.showMessageDialog(getParent(), "请输入数字!");
            FLAG = false;
        }

        if (FLAG && device_falg) {
            if (Double.parseDouble(two) == 0) {
                JOptionPane.showMessageDialog(getParent(), "被除数不能为0!");
                FLAG = false;
                device_falg=false;
            }
        }

        return FLAG;
    }

    public double Plus(double one, double two) {
        return one + two;
    }

    public double Multiply(double one, double two) {
        return one * two;
    }

    public double Divice(double one, double two) {
        return one / two;
    }

    public double Reduce(double one, double two) {
        return one - two;
    }

    public void Clear() {
        one.setText("");
        two.setText("");
        result.setText("");
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        Object o = e.getSource();
        if (o == reset) {
            Clear();
            return;
        }
        if (o == divice) {
            device_falg = true;
        }
        if (!Format()) {
            return;
        }
        double one = Double.parseDouble(this.one.getText());
        double two = Double.parseDouble(this.two.getText());
        double result = 0;
        if (o == plus) {
            result = Plus(one, two);
        } else if (o == reduce) {
            result = Reduce(one, two);
        } else if (o == multiply) {
            result = Multiply(one, two);
        } else if (o == divice) {
            result = Divice(one, two);
        }
        this.result.setText("" + result);
    }
    public static void main(String[] args) {
        new Calculate();
    }
}

追问

谢谢各位

Answer 2

比一楼的简单

package com.isoftstone.baidu;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

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

public class CalcDemo extends JFrame {

    private static final long serialVersionUID = 111111L;
    private JLabel label1 = new JLabel();
    private JLabel label2 = new JLabel();
    private JLabel label3 = new JLabel();
    private JTextField field1 = new JTextField();
    private JTextField field2 = new JTextField();
    private JTextField field3 = new JTextField();
    private JButton button1 = new JButton();
    private JButton button2 = new JButton();
    private JButton button3 = new JButton();
    private JButton button4 = new JButton();

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

    public CalcDemo() {
        super("简易计算器");
        try {
            init();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private void init() {
        this.setSize(300, 300);
        label1.setText("第一个数：");
        label2.setText("第二个数：");
        label3.setText("结果：");
        button1.setText("加法");
        button2.setText("减法");
        button3.setText("乘法");
        button4.setText("除法");
        label1.setBounds(10, 10, 100, 22);
        label2.setBounds(10, 35, 100, 22);
        label3.setBounds(10, 60, 100, 22);
        field1.setBounds(110, 10, 100, 22);
        field2.setBounds(110, 35, 100, 22);
        field3.setBounds(110, 60, 100, 22);
        button1.setBounds(10, 85, 100, 22);
        button2.setBounds(110, 85, 100, 22);
        button3.setBounds(110, 110, 100, 22);
        button4.setBounds(10, 110, 100, 22);
        button1.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent e) {
                calculate(1);
            }
        });
        button2.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent e) {
                calculate(2);
            }
        });
        button3.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent e) {
                calculate(3);
            }
        });
        button4.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent e) {
                calculate(4);
            }
        });
        JPanel panel = (JPanel) this.getContentPane();
        panel.setLayout(null);
        panel.add(label1);
        panel.add(label2);
        panel.add(label3);
        panel.add(field1);
        panel.add(field2);
        panel.add(field3);
        panel.add(button1);
        panel.add(button2);
        panel.add(button3);
        panel.add(button4);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setResizable(false);
        this.setLocationRelativeTo(null);
        this.setVisible(true);

    }

    private void calculate(int operators) {
        try {
            double num1 = Double.parseDouble(field1.getText());
            double num2 = Double.parseDouble(field2.getText());
            switch (operators) {
                case 1:
                    field3.setText((num1 + num2) + "");
                    break;
                case 2:
                    field3.setText((num1 - num2) + "");
                    break;
                case 3:
                    field3.setText((num1 * num2) + "");
                    break;
                case 4:
                    field3.setText((num1 / num2) + "");
                    break;
                default:
                    break;
            }
        } catch (NumberFormatException e) {
            JOptionPane.showMessageDialog(this, "请输入正确的数值!!!", "警告", 1);
        }
    }
}

Answer 3

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

public class Calculator extends Applet implements ActionListener{
	Button backButton=new Button("退格");
	Button clearButton=new Button("清除");
	Panel p1 = new Panel(new FlowLayout());
	Panel p2 = new Panel(new GridLayout(2,1));
	Panel p3 = new Panel(new GridLayout(4,5,5,5));
	TextField t=new TextField("0");
	float num1=0;
	char ch='#';boolean can=false;
	public void init(){
	t.setFont(new Font("宋体",Font.BOLD,25));
	backButton.setFont(new Font("黑体",Font.BOLD,15));
	backButton.setForeground(Color.red);
	clearButton.setFont(new Font("黑体",Font.BOLD,15));
	clearButton.setForeground(Color.red);
	p1.add(backButton);
	p1.add(clearButton);
	backButton.addActionListener(this);
	clearButton.addActionListener(this);
	p2.add(t);
	p2.add(p1);
	p2.setBackground(Color.black);
	p3.setBackground(Color.black);
	this.setLayout(new BorderLayout());
	this.add(p2,"North");
	this.add(p3,"Center");
	String buttonStr = "789/A456*B123-C0.D+=";
	for (int i = 0; i < buttonStr.length(); i++)
	this.addButton(p3,buttonStr.substring(i, i + 1));
	}
	private void addButton(Container c, String s)
	{Button b = new Button(s);
	if (s.equals("A"))
		b.setLabel("sqrt");
	else if (s.equals("B"))
		b.setLabel("1/x");
	else if (s.equals("C"))
		b.setLabel("%");
	else if (s.equals("D"))
		b.setLabel("+/-");
	b.setForeground(Color.blue);
	b.setFont(new Font("黑体",Font.BOLD,15));
	c.add(b);
	b.addActionListener(this);
}
public void actionPerformed(ActionEvent e){
	String act=e.getActionCommand();
	if(e.getSource()==backButton){
		if(t.getText().length()>1)t.setText(t.getText().substring(0, t.getText().length()-1));
		else t.setText("0");
	return;}
	if(e.getSource()==clearButton){t.setText("0");ch='#';return;}
	if(act.equals("+/-")){
		if(t.getText().charAt(0)!='-')t.setText("-"+t.getText());
		else t.setText(t.getText().substring(1));return;
	}
	if(act.equals(".")){t.setText(t.getText()+act);return;}
	if(act!="1/x"&&act.charAt(0)>='0'&&act.charAt(0)<='9'){
		if(can){t.setText(act);can=false;}
		else{try{if(Float.parseFloat(t.getText())==0)
			{if(t.getText().equals("0."))t.setText(t.getText()+act);
				else t.setText(act);
			return;
			}
		else {t.setText(t.getText()+act);return;}
		}catch(NumberFormatException e1){
			JOptionPane.showMessageDialog(null, "输入格式错误！", "警告！",
JOptionPane.ERROR_MESSAGE);return;}
		}
		}

	if(act.equals("+")||act.equals("-")||act.equals("*")||act.equals("/")||act.equals("%")){
		if(ch!='#'){try{num1=cacu(num1,ch,Float.parseFloat(t.getText()));
					t.setText(String.valueOf(num1));ch=act.charAt(0);can=true;return;
		}catch(NumberFormatException e1){JOptionPane.showMessageDialog(null, "输入格式错误！", "警告！",
JOptionPane.ERROR_MESSAGE);return;}
			}
	else{try{num1=Float.parseFloat(t.getText());
			ch=act.charAt(0);can=true;return;
		}catch(NumberFormatException e1){JOptionPane.showMessageDialog(null, "输入格式错误！", "警告！",
JOptionPane.ERROR_MESSAGE);return;}
		}
	}
	if(act.equals("sqrt")){try{float num=(float)Math.sqrt(Float.parseFloat(t.getText()));
	t.setText(String.valueOf(num));can=true;return;
	}catch(NumberFormatException e1){JOptionPane.showMessageDialog(null, "输入格式错误！", "警告！",
JOptionPane.ERROR_MESSAGE);return;}
	}
	if(act.equals("1/x")){try{float num=1/Float.parseFloat(t.getText());
	t.setText(String.valueOf(num));can=true;return;
	}catch(NumberFormatException e1){JOptionPane.showMessageDialog(null, "输入格式错误！", "警告！",
JOptionPane.ERROR_MESSAGE);return;}
	catch(ArithmeticException e1){JOptionPane.showMessageDialog(null, "除0错误！", "警告！",
JOptionPane.ERROR_MESSAGE);return;}
	}
	if(act.equals("=")){can=true;
		try{if(ch=='#')return;
		float num=Float.parseFloat(t.getText());
		num1=cacu(num1,ch,num);
		t.setText(String.valueOf(num1));
		ch='#';return;
		}catch(NumberFormatException e1){JOptionPane.showMessageDialog(null, "输入格式错误！", "警告！",
JOptionPane.ERROR_MESSAGE);return;}
	}
}
public float cacu(float a,char c,float b){
		float sum;
		switch(c){
			case '+':sum=a+b;break;
			case '-':sum=a-b;break;
			case '*':sum=a*b;break;
			case '/':if(b==0){JOptionPane.showMessageDialog(null, "除0错误！", "警告！",
JOptionPane.ERROR_MESSAGE);return 0;}sum=a/b;break;
			case '%':if(b==0){JOptionPane.showMessageDialog(null, "除0错误！", "警告！",
JOptionPane.ERROR_MESSAGE);return 0;}sum=a%b;break;
			default:return 0;
		}
		return sum;
	}
}

Answer 4

说实在的，你写的这个计算器不怎么样。特别是布局。
我给你一个很简单的吧。你自己学习一下。。

import java.awt.*;
import java.awt.event.*;
/**
*
* @author zzj
*
*/
public class Jisuanqi extends WindowAdapter {
Panel p1 = new Panel();
Panel p2 = new Panel();
Panel p3 = new Panel();
TextField txt;
private Button[] b = new Button[17];
private String ss[] = { "7", "8", "9", "+", "4", "5", "6", "-", "1", "2",
"3", "*", "清空", "0", "=", "/", "关闭" };
static double a;
static String s, str;//定义变量 创建对像

public static void main(String args[]) {
(new Jisuanqi()).frame();
}

public void frame() {
Frame fm = new Frame("简单计算器");
for (int i = 0; i <= 16; i++) {
b[i] = new Button(ss[i]);
}
for (int i = 0; i <= 15; i++) {
p2.add(b[i]);
} //创建按钮 并添加到P2
b[16].setBackground(Color.yellow);
txt = new TextField(15);
txt.setEditable(false);
for (int i = 0; i <= 16; i++) {
b[i].addActionListener(new buttonlistener());//添加监听器
}
b[16].addActionListener(new close());
fm.addWindowListener(this);
fm.setBackground(Color.red);
p1.setLayout(new BorderLayout());
p1.add(txt, "North");
p2.setLayout(new GridLayout(4, 4));
p3.setLayout(new BorderLayout());
p3.add(b[16]);
fm.add(p1, "North");
fm.add(p2, "Center");
fm.add(p3, "South");
fm.pack();
fm.setVisible(true);//都是些窗中设置 添加相关组件和监听器
}

public void windowClosing(WindowEvent e) {
System.exit(0);//退出系统
}

class buttonlistener implements ActionListener {//编写监听器事件 通过按键得出给果
public void actionPerformed(ActionEvent e) {
Button btn = (Button) e.getSource();
if (btn.getLabel() == "=") {
jisuan();
str = String.valueOf(a);
txt.setText(str);
s = "";
} else if (btn.getLabel() == "+") {
jisuan();
txt.setText("");
s = "+";
} else if (btn.getLabel() == "-") {
jisuan();
txt.setText("");
s = "-";
} else if (btn.getLabel() == "/") {
jisuan();
txt.setText("");
s = "/";

} else if (btn.getLabel() == "*") {
jisuan();
txt.setText("");
s = "*";
} else {
txt.setText(txt.getText() + btn.getLabel());

if (btn.getLabel() == "清空")
txt.setText("");
}
}

public void jisuan() {//编写具体计算方法
if (s == "+")
a += Double.parseDouble(txt.getText());
else if (s == "-")
a -= Double.parseDouble(txt.getText());
else if (s == "*")
a *= Double.parseDouble(txt.getText());
else if (s == "/")
a /= Double.parseDouble(txt.getText());
else
a = Double.parseDouble(txt.getText());
}
}
}

class close implements ActionListener {//退出
public void actionPerformed(ActionEvent e) {
System.exit(0);
}
}

Answer 5

- -|||……虽然我也有计算器的代码，不过我还是给你指正下你的问题出在哪里吧。很无语……
public void actionPerformed(ActionEvent e){
Button0.addActionListener(this);
if(e.getActionCommand().equals("Button1"))
Text1.setText(e.getActionCommand());
}
你应该把这里面的Button0.addActionListener(this);添加到Calculator类函数中.因为你是在Calculator类中触发了按钮事件，然后在actionPerformed(ActionEvent e)函数中处理它。你把它放到actionPerformed(ActionEvent e)函数中，又怎么能触发事件呢……
你修改看看吧，这样应该就可以用了