本文目录一览：
如何用Java编写四则运算程序？
（首先建个类，把这些复制粘贴进去）
import java.awt.*;
import javax.swing.*;
public class F {
JFrame frame = new JFrame("计算机");
JPanel pl = new JPanel();
JPanel p2 = new JPanel();
static JTextField show = new JTextField();
static JButton b0 = new JButton("0");
static JButton b1 = new JButton("1");
static JButton b2 = new JButton("2");
static JButton b3 = new JButton("3");
static JButton b4 = new JButton("4");
static JButton b5 = new JButton("5");
static JButton b6 = new JButton("6");
static JButton b7 = new JButton("7");
static JButton b8 = new JButton("8");
static JButton b9 = new JButton("9");
JButton bjia = new JButton("+");
JButton bjian = new JButton("-");
JButton bcheng = new JButton("*");
JButton bchu = new JButton("/");
JButton bdian = new JButton(".");
JButton bdeng = new JButton("=");
JButton bqingchu = new JButton("清除");
public void y() {
pl.setLayout(new GridLayout(1, 1));
pl.add(show);
}
public void p() {
b1.addActionListener(new U());
b2.addActionListener(new U());
b3.addActionListener(new U());
b4.addActionListener(new U());
b5.addActionListener(new U());
b6.addActionListener(new U());
b7.addActionListener(new U());
b8.addActionListener(new U());
b9.addActionListener(new U());
b0.addActionListener(new U());
bjia.addActionListener(new Fu());
bjian.addActionListener(new Fu());
bcheng.addActionListener(new Fu());
bchu.addActionListener(new Fu());
bdeng.addActionListener(new Deng());
bqingchu.addActionListener(new Qing());
p2.setLayout(new GridLayout(6, 3));
p2.add(b1);
p2.add(b2);
p2.add(b3);
p2.add(b4);
p2.add(b5);
p2.add(b6);
p2.add(b7);
p2.add(b8);
p2.add(b9);
p2.add(b0);
p2.add(bjia);
p2.add(bjian);
p2.add(bcheng);
p2.add(bchu);
p2.add(bdian);
p2.add(bqingchu);
p2.add(bdeng);
}
public void o() {
frame.setLayout(new BorderLayout());
frame.add(pl, BorderLayout.NORTH);
frame.add(p2, BorderLayout.CENTER);
frame.setSize(400, 300);
frame.setVisible(true);
}
public static void main(String[] args) {
F f = new F();
f.y();
f.p();
f.o();
}
}
(再新建个类 把这些也复制粘贴进去)
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class U implements ActionListener {
public static String str = "";
public static String a = "";
public static String b = "";
public static String k = "";
public void actionPerformed(ActionEvent e) {
String w = e.getActionCommand();//字
if (k.equals("")) {
a += w;
F.show.setText(a);
} else {
b += w;
F.show.setText(b);
}
}
}
（再新建一个，把下面的复制粘贴）
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Deng implements ActionListener {
public void actionPerformed(ActionEvent e) {
int a = Integer.parseInt(U.a);
int b = Integer.parseInt(U.b);
int c = 0;
if (U.k.equals("+")) {
c = a + b;
} else
if (U.k.equals("-")) {
c = a - b;
} else
if (U.k.equals("*")) {
c = a * b;
} else
if (U.k.equals("/")) {
c = a / b;
} else {
}
String d = String.valueOf(c);
F.show.setText(d);
U.a = d;
U.b = "";
U.k = "";
}
}
（在建一个 复制粘贴）
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Fu implements ActionListener {
public void actionPerformed(ActionEvent e) {
String a = e.getActionCommand();//字
U.k = a;
}
}
（在建一个）
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Qing implements ActionListener {
public void actionPerformed(ActionEvent e) {
U.a = "";
U.b = "";
U.k = "";
F.show.setText("");
}
}
Java中怎么能实现从键盘输入几个数字后进行四则运算
Java中提供了一个Scanner类，接受用户从键盘敲入的数值，具体 使用例子如下：
Scanner s = new Scanner(System.in);//接受键盘输入的数值。
int str = s.next();//将输入的字符串转换为int类型，就可以进行四则运算。
java的四则运算
import java.util.Scanner;
public class SimpleCalc {
public SimpleCalc() {}
public static void main(String[] args) {
calc();
}
public static void calc() {
Scanner reader = new Scanner(System.in);
char op;
double num1, num2, result;
while (true) {
System.out.println("请选择运算符:1、+;2、-;3、*;4、/");
if (reader.hasNext()) {
op = reader.nextChar();
switch (op) {
case '1':
op = 1;
break;
case '2':
op = 2;
break;
case '3':
op = 3;
break;
case '4':
op = 4;
break;
case 0://EOF
default:
System.out.println("输入非法！");
op = 0;
break;
}
if (0 != op) {
try {
System.out.println("请输入第一个运算数:");
if (reader.hasNext()) {
num1 = reader.nextDouble();
}
System.out.println("请输入第二个运算数:");
if (reader.hasNext()) {
num2 = reader.nextDouble();
}
switch (op) {
case 1:
result = num1 + num2;
break;
case 2:
result = num1 - num2;
break;
case 3:
result = num1 * num2;
break;
case 4:
result = num1 / num2;
break;
}
System.out.println("运算结果为:"+ result);
System.out.println("是否继续？是(Y)/否(N):");
} catch(Exception err) {
System.out.println("输入非法！");
}
if (!isContinue(reader)) {
break;
}
}
}
}
}
public static boolean isContinue(Scanner reader) {
boolean flag = false;
if (reader.hasNext()) {
char isContinue = reader.next().charAt(0);
if ('N' == isContinue) {
flag = false;
} else if ('Y' == isContinue) {
flag = true;
} else {
System.out.println("是否继续？是(Y)/否(N):");
flag = isContinue(reader);
}
}
return flag;
}
}
定义一个方法，实现四则运算的功能。java
import java.text.DecimalFormat;
import java.util.Scanner;
public class Zhidao {
public static void main(String[] args) {
String condition = "";
Zhidao zhidao = new Zhidao();
do{
Scanner scanner = new Scanner(System.in);
try{
System.out.print("请输入第一个数：");
double x = scanner.nextDouble();
System.out.print("请输入第二个数：");
double y = scanner.nextDouble();
System.out.print("请输入运算符：");
String s = scanner.next();
char z = s.charAt(0);
zhidao.yunsuan(x, y, z);
}catch(Exception e){
System.out.println("请输入正确的数据！");
}
System.out.print("是否继续？continue：继续，任意字符：结束");
condition = scanner.next();
}while("continue".equals(condition));
}
public static void yunsuan(double x,double y,Character z){
DecimalFormat r=new DecimalFormat();
r.applyPattern("#0.00");
if(z.equals('+')){
System.out.println(x+"+"+y+"=" + r.format((x+y)));
} else if(z.equals('-')){
System.out.println(x+"-"+y+"=" + r.format((x-y)));
} else if(z.equals('*')){
System.out.println(x+"*"+y+"=" + r.format((x*y)));
} else if(z.equals('/')){
if(y==0){
System.out.println("被除数不能为0");
} else{
System.out.println(x+"/"+y+"=" + r.format((x/y)));
}
}else{
System.out.println("无法识别改运算符");
}
}
}
java简单的四则运算.
public class Arithmetic {
public static void Ari(){
Scanner scan = new Scanner(System.in);
StringBuffer buffer = new StringBuffer();
DecimalFormat dec = new DecimalFormat("0.00");//格式化结果保留两位小数
String all = "";//所有的计算表达式连在一起
System.out.println("请输入表达式的个数,只能为正整数");
int n = scan.nextInt();
System.out.println("请依次输入要计算的表达式");
for(int i=0;in+1;i++){
buffer = buffer.append(scan.nextLine()+",");
}
all = buffer.substring(0, buffer.lastIndexOf(","));
String allAri[] = all.split(",");
String ari = "";//不同的算法表达式
float add;//加法的计算结果
float subtract;//减肥的计算结果
float multi;//乘法的计算结果
float divison;//除法的计算结果
int model;//模运算的计算结果
for(int j=0;jallAri.length;j++){
ari = allAri[j];
if(ari.contains("+")){
String tempAry[] = ari.split("[+]");
add = Float.valueOf(tempAry[0])+Float.valueOf(tempAry[1]);
System.out.println(dec.format(add));
}else if(ari.contains("-")){
String tempAry[] = ari.split("[-]");
subtract = Float.valueOf(tempAry[0])-Float.valueOf(tempAry[1]);
System.out.println(dec.format(subtract));
}else if(ari.contains("*")){
String tempAry[] = ari.split("[*]");
multi = Float.valueOf(tempAry[0])*Float.valueOf(tempAry[1]);
System.out.println(dec.format(multi));
}else if(ari.contains("/")){
String tempAry[] = ari.split("[/]");
divison = Float.valueOf(tempAry[0])/Float.valueOf(tempAry[1]);
System.out.println(dec.format(divison));
}else if(ari.contains("%")){
String tempAry[] = ari.split("[%]");
model = Integer.valueOf(tempAry[0])%Integer.valueOf(tempAry[1]);
System.out.println(model);
}
}
}
public static void main(String[] args) {
Ari();
}
}
测试结果截图如下：
你的测试用例的输入的表达式的个数是4个，但下面的计算表达式好像少了一个，所以我加了一个除法的计算表达式，若理解有误，还望说明。
