Write an application that simulates a calculator, using panel and grid layout, adding a text box, 10 number buttons (0~9), 4 addition, subtraction, multiplication and division buttons, an equal sign button, and a clear button, A square root button and a backspace button require the calculation formula and results to be displayed in the text box. The effect is as shown in the figure below.
Java simple calculator code:
import javax.swing.*;
import javax.swing.JTextField;
import java.awt.*;
import java.awt.event.*;
import java.lang.*;
import java.awt.Color;
public class Ex5_2 extends JFrame implements ActionListener
{
private JPanel p1 = new JPanel(); //创建面板
private JPanel p2 = new JPanel();
private JTextField t1; //文本框1用来显示输入信息
private JTextField t2; //文本框2用来显示结果信息
private JLabel label; //标签信息
StringBuffer str; //显示屏所显示的字符串
double x,y; //x和y都是运算数
int z; //Z表示单击了那一个运算符.0表示"+",1表示"-",2表示"*",3表示"/"
private JButton b[] = new JButton[12]; //创建一个有12个按钮的数组
private JButton b1,b2,b3,b4,b5,b6,b7,b8; //算术功能按钮
public Ex5_2()
{
super("简易计算器"); //窗口名称
Container c = getContentPane(); //创建内容面板对象
t1 = new JTextField(30);
t1.setEditable(false); //只能显示，不能编辑
t2 = new JTextField(30);
t2.setEditable(false); //只能显示，不能编辑
label = new JLabel("欢迎使用小巫版计算器^_^o~ 努力！");
label.setForeground(Color.blue);
//创建一个空字符串缓冲区
str=new StringBuffer();
p2.add(label); //添加标签到面板
p2.add(t2); //添加文本框到面板
p2.add(t1); //添加文本框到面板
p2.setLayout(new GridLayout(4,1)); //把面扳布局为4行1列
for(int i=0;i<10;i++) //分别为数组中0~9号的按钮设置标签，并注册监听器
{
String s=""+i;
b[i]= new JButton(s);
b[i].addActionListener(this);
}
//实例化各个按钮
b[10]= new JButton("-/+"); b[11]= new JButton(".");
b1= new JButton("/"); b2= new JButton("Back");
b3= new JButton("*"); b4= new JButton("C");
b5= new JButton("+"); b6= new JButton("Sqrt");
b7= new JButton("-"); b8= new JButton("=");
//设置按钮前景色
for(int i=0;i<12;i++)
{
b[i].setForeground(Color.blue);
}
b1.setForeground(Color.red); b3.setForeground(Color.red);
b5.setForeground(Color.red); b7.setForeground(Color.red);
b2.setForeground(Color.blue); b4.setForeground(Color.blue);
b6.setForeground(Color.red); b8.setForeground(Color.blue);
//添加到面板
p1.add(b[7]); p1.add(b[8]); p1.add(b[9]); p1.add(b1); p1.add(b2);
p1.add(b[4]); p1.add(b[5]); p1.add(b[6]); p1.add(b3); p1.add(b4);
p1.add(b[1]); p1.add(b[2]); p1.add(b[3]); p1.add(b5); p1.add(b6);
p1.add(b[0]); p1.add(b[10]); p1.add(b[11]);p1.add(b7);p1.add(b8);
p1.setLayout(new GridLayout(4,5,5,5));
//注册监听器
b[10].addActionListener(this); b[11].addActionListener(this);
b1.addActionListener(this); b2.addActionListener(this);
b3.addActionListener(this); b4.addActionListener(this);
b5.addActionListener(this); b6.addActionListener(this);
b7.addActionListener(this); b8.addActionListener(this);
//将面板添加到内容面板
c.add(p2);
c.add(p1);
c.setLayout(new FlowLayout()); //设置为顺序布局
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //设置窗口关闭动作
setVisible(true); //设置为可见
setResizable(false); //禁止调整框架大小
setSize(400,300); //设置窗口大小
}
//主方法实现创建一个窗口
public static void main(String[] args)
{ Ex5_2 f = new Ex5_2(); }
//按钮的事件处理
public void actionPerformed(ActionEvent e)
{
try
{
if(e.getSource()==b4) //选择"C"清零
{
t1.setText("0"); //把文本框清零
t1.setHorizontalAlignment(JTextField.RIGHT); //文本对齐右边
str.setLength(0); //清空字符串缓冲区以准备接收新的输入运算数
}
else if(e.getSource()==b[10])//单击"+/-"选择输入的运算数是正数还是负数
{
x=Double.parseDouble(t1.getText().trim());//trim函数作用是去掉字符串中的空格
t1.setText(""+(-x));
t1.setHorizontalAlignment(JTextField.RIGHT);
}
else if (e.getSource()==b5)//单击加号按钮获得x的值和z的值并清空y的值
{
x=Double.parseDouble(t1.getText().trim());
str.setLength(0);
y=0d;
z=0;
}
else if(e.getSource()==b7)//单击减号按钮获得x的值和z的值并清空y的值
{
x=Double.parseDouble(t1.getText().trim());
str.setLength(0);
y=0d;
z=1;
}
else if(e.getSource()==b3)//单击乘号按钮获得x的值和z的值并清空y的值
{
x=Double.parseDouble(t1.getText().trim());
str.setLength(0);
y=0d;
z=2;
}
else if(e.getSource()==b1)//单击除号按钮获得x的值和z的值并清空y的值
{
x=Double.parseDouble(t1.getText().trim());
str.setLength(0);
y=0d;
z=3;
}
else if(e.getSource()==b8)//单击等号按钮输出计算结果
{
str.setLength(0);
switch(z)
{
case 0: t1.setText(""+(x+y)); t1.setHorizontalAlignment(JTextField.RIGHT);break;
case 1: t1.setText(""+(x-y)); t1.setHorizontalAlignment(JTextField.RIGHT);break;
case 2: t1.setText(""+(x*y)); t1.setHorizontalAlignment(JTextField.RIGHT);break;
case 3: t1.setText(""+(x/y)); t1.setHorizontalAlignment(JTextField.RIGHT);break;
}
}
else if(e.getSource()==b[11])//单击"."按钮输入小数
{
if(t1.getText().trim().indexOf('.')!=-1)//判断字符串中是否已经包含了小数点
{
}
else //如果没有小数点
{
if(t1.getText().trim().equals("0"))//如果初时显示为0
{
t1.setText(str.append(e.getActionCommand()).toString());
t1.setHorizontalAlignment(JTextField.RIGHT);
}
else if(t1.getText().trim().equals(""))//如果初时显示为空则不做任何操作
{}
else
{
t1.setText(str.append(e.getActionCommand()).toString());
t1.setHorizontalAlignment(JTextField.RIGHT);
}
}
y=0d;
}
else if(e.getSource()==b6) //求平方根
{
x=Double.parseDouble(t1.getText().trim());
if(x<0)
{
t1.setText("数字格式异常");
t1.setHorizontalAlignment(JTextField.RIGHT);
}
else
{
t1.setText(""+Math.sqrt(x));
t1.setHorizontalAlignment(JTextField.RIGHT);
}
str.setLength(0);
y=0d;
}
else
{
if(e.getSource()==b[0])//如果选择的是"0"这个数字键
{
if(t1.getText().trim().equals("0"))//如果显示屏显示的为零不做操作
{}
else
t1.setText(str.append(e.getActionCommand()).toString());
t1.setHorizontalAlignment(JTextField.RIGHT);
y=Double.parseDouble(t1.getText().trim());
}
else if (e.getSource()==b2) //选择的是back键
{
if(!t1.getText().trim().equals("0"))//如果显示屏显示的不是零
{
if(str.length()!=1)
{
t1.setText(str.delete(str.length()-1,str.length()).toString());//可能抛出字符串越界异常
t1.setHorizontalAlignment(JTextField.RIGHT);
}
else
{
t1.setText("0"); t1.setHorizontalAlignment(JTextField.RIGHT);
str.setLength(0);
}
}
y=Double.parseDouble(t1.getText().trim());
}
else
{
t1.setText(str.append(e.getActionCommand()).toString());
t1.setHorizontalAlignment(JTextField.RIGHT);
y=Double.parseDouble(t1.getText().trim());
}
}
}
catch(NumberFormatException e1){ t1.setText("数字格式异常");
t1.setHorizontalAlignment(JTextField.RIGHT); }
catch(StringIndexOutOfBoundsException e1){t1.setText("字符串索引越界");
t1.setHorizontalAlignment(JTextField.RIGHT);}
}
}Running renderings:
The design of a Java simple calculator program is completed. I hope this article can inspire you to write a calculator. This is just a simple calculator, and you can continue to use it to improve the functions of the calculator.
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