不仅可以加减还可以乘除，代码如下：
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package 计算器;
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class Calculator extends JFrame implements ActionListener {
boolean flag = false;
JTextField jtf = new JTextField();
public static void main(String[] args) {
new Calculator();
}
public Calculator() {
setSize(300, 300);
setTitle("计算器");
Container c = getContentPane();
jtf.setHorizontalAlignment(JTextField.RIGHT);
JButton jb = new JButton("=");
jb.addActionListener(this);
JPanel jp = new JPanel();
c.add(jtf, BorderLayout.NORTH);
c.add(jp, BorderLayout.CENTER);
c.add(jb, BorderLayout.SOUTH);
jp.setLayout(new GridLayout(4, 4));
addButton(jp);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setResizable(false);
setVisible(true);
}
public void addButton(JPanel jp) {
JButton b = null;
b = new JButton("1");
b.addActionListener(this);
jp.add(b);
b = new JButton("2");
b.addActionListener(this);
jp.add(b);
b = new JButton("3");
b.addActionListener(this);
jp.add(b);
b = new JButton("+");
b.addActionListener(this);
jp.add(b);
b = new JButton("4");
b.addActionListener(this);
jp.add(b);
b = new JButton("5");
b.addActionListener(this);
jp.add(b);
b = new JButton("6");
b.addActionListener(this);
jp.add(b);
b = new JButton("-");
b.addActionListener(this);
jp.add(b);
b = new JButton("7");
b.addActionListener(this);
jp.add(b);
b = new JButton("8");
b.addActionListener(this);
jp.add(b);
b = new JButton("9");
b.addActionListener(this);
jp.add(b);
b = new JButton("*");
b.addActionListener(this);
jp.add(b);
b = new JButton("0");
b.addActionListener(this);
jp.add(b);
b = new JButton(".");
b.addActionListener(this);
jp.add(b);
b = new JButton("C");
b.addActionListener(this);
jp.add(b);
b = new JButton("/");
b.addActionListener(this);
jp.add(b);
}
public void actionPerformed(ActionEvent e) {
if (e.getActionCommand() == "=") {
if (jtf.getText().matches("\\d+\\.?\\d*[\\+\\-\\*\\/]\\d+\\.?\\d*")) {
String s = jtf.getText();
Pattern p = Pattern.compile("\\d+\\.?\\d*");
Matcher m = p.matcher(s);
m.find();
double firstNum = Double.parseDouble(m.group());
m.find();
double secondNum = Double.parseDouble(m.group());
if (jtf.getText().matches("\\d+\\.?\\d*\\+\\d+\\.?\\d*")) {
jtf.setText("" + (firstNum + secondNum));
} else if (jtf.getText().matches("\\d+\\.?\\d*\\-\\d+\\.?\\d*")) {
jtf.setText("" + (firstNum - secondNum));
} else if (jtf.getText().matches("\\d+\\.?\\d*\\*\\d+\\.?\\d*")) {
jtf.setText("" + (firstNum * secondNum));
} else if (jtf.getText().matches("\\d+\\.?\\d*\\/\\d+\\.?\\d*")) {
jtf.setText("" + (firstNum / secondNum));
}
} else {
JOptionPane.showMessageDialog(null, "请输入正确表达式！");
}
flag = true;
} else if (e.getActionCommand() == "C") {
jtf.setText("");
} else {
if (flag) {
if (e.getActionCommand() != "+" e.getActionCommand() != "-"
e.getActionCommand() != "*"
e.getActionCommand() != "/") {
//System.out.println(e.getActionCommand() != "+");
jtf.setText("");
}
flag = false;
}
jtf.setText(jtf.getText() + e.getActionCommand());
}
}
}
import java.util.Scanner;
public class JianJian {
public static void main(String[] args) {
System.out.println("一百以内的加减法");
System.out.println("输入-1,退出系统");
Scanner sc = new Scanner(System.in);
int score = 0;
int nums = 0;
while (true) {
int x = (int) (Math.random() * 2);//随机一个0,1的数字,当数字是1的时候,输出加法,当数字是0的时候,输出减法
int a = (int) (Math.random() * 100);
int b = (int) (Math.random() * 100);
if (x == 1) {
System.out.print(a + "+" + b + "=");
int c = sc.nextInt();
if (c == -1) {
break;
}
nums++;
if (c == (a + b)) {
score = score + 10;
}
} else {
if (a b) {// 排除a-b0的情况.保证结果都是大于0的
b = a + b;
a = b - a;
b = b - a;
}
System.out.print(a + "-" + b + "=");
int c = sc.nextInt();
if (c == -1) {
break;
}
nums++;
if (c == (a - b)) {
score = score + 10;
}
}
}
System.out.println("做了" + nums + "道题目,得分: " + score);
}
}
输出
一百以内的加减法
输入-1,退出系统
87-18=59
23-6=17
72-30=42
97+14=-1//-1表示退出系统,所以不算做一道题
做了3道题目,得分: 20
import java.util.Scanner;
public class P {
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
P prm=new P();
int a,b;
System.out.println("请输入两个整数（以空格分隔）：");
a=sc.nextInt();
b=sc.nextInt();
System.out.println("两数相加后等于："+prm.add(a,b));
System.out.println("两数相减后等于："+prm.sub(a,b));
System.out.println("两数相除后等于："+prm.divide(b,a));
sc.close();
}
int add(int a,int b) {
return a+b;
}
int sub(int a,int b) {
if(ab)
return a-b;
else
return b-a;
}
int divide(int a,int b) {
if(0==b)
System.out.println("错误");
if(0==a)
System.out.println("除数不能为0");
return b/a;
}
}
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