利用java swing编写一个简易的计算器，实现了括号，优先级，三角函数，阶乘等功能
利用java swing编写一个简易的计算器
- 背景
- 效果图
- 一、默认图
- 二、计算三角函数
- 三、阶乘运算
- 四、常见的四则运算（实现了优先级）
- 代码
本文借鉴了“初识Java,实现简易计算器(带括号)”这篇文章，在其基础上增加了“sin cos 1/x 阶乘 求余 开方 正负号”等功能
背景
我们期末的Java实验就是利用swing写一个计算器出来，实现上述功能，网上找了好多文章，但大多都只实现了四则运算，没有括号，有些都不能连加。我最后找到的这个倒是挺适合修改的。
附上我酷爱的IDEA和汤之介
效果图
一、默认图
中上方是运算栏，右侧的历史记录，历史记录右下角的按钮可以清除历史记录，左下方按钮
二、计算三角函数
sin30、1+sin30、sin(15+45)这三种都能运算
三、阶乘运算
阶乘运算有个小bug，它只能用于计算第一个数或最后一个数的阶乘
四、常见的四则运算（实现了优先级）
代码
我的代码臃肿，而且肯定还有很多bug没找出来，感谢各位大佬指点。
package calculator;
import javax.swing.*;
import javax.swing.plaf.DesktopPaneUI;
import java.awt.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.math.BigDecimal;
import java.util.LinkedList;
import java.util.Objects;
public class calculator {
public static void main(String[] args) {
new CalculatorFrame("计算器");
}
}
class CalculatorFrame extends Frame {
TextArea display,record;//显示屏与历史记录
String nullMessage = "尚无历史记录...";
//组件value
String[] value = {"%", "(", ")", "CE", "!", "sin", "cos", "<-", "1/x", "^", "√", "/",
"7", "8", "9", "*", "4", "5", "6", "-", "1", "2", "3", "+", "-/+", "0", ".", "="};
//构造函数，计算器入口
public CalculatorFrame(String title){
super(title);//计算器名称
setMainFrame();//窗口基本设置
setButton();//设置按钮
}
private void setMainFrame(){
this.setLayout(null);//设置窗口布局为空
this.setBounds(400,200,720,520);//设置窗口大小
this.setResizable(false);//窗口是否可调整大小
this.setVisible(true);//窗口可视
//关闭窗口监听事件
this.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e){
System.exit(0);
}
});
//设置显示屏
display = new TextArea("0",8,52,3);//文本区域
display.setBounds(20, 40, 490, 120);
display.setEditable(false);
display.setBackground(new Color(230, 230, 230));
display.setFont(new Font("幼圆", Font.BOLD, 15));
this.add(display);
//设置历史记录
record = new TextArea(nullMessage, 52, 52, 3);
record.setBounds(510, 40, 190, 460);
record.setEditable(false);
record.setBackground(new Color(230,230,230));
record.setFont(new Font("幼圆", Font.BOLD, 10));
//清空历史记录的按钮
JButton deleteButton = new JButton();
deleteButton.setBounds(660, 460, 20, 20);
deleteButton.addMouseListener(new MouseAdapter() {
@Override
//鼠标点击，清空历史记录
public void mousePressed(MouseEvent e){
record.setText(nullMessage);
}
});
this.add(deleteButton);
this.add(record);
}
private void setButton(){
for(int i=0; i<value.length;i++){
addButton(value[i],20+122*(i%4), 165+48*(int)(Math.floor((i/4))));
}
}
private void addButton(String val, int x, int y){
Button button = new Button(val);
button.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
button.setBounds(x,y,117,43);
button.setFont(new Font("标楷体", Font.BOLD, 15));
//增加点击事件
button.addMouseListener(new MouseAdapter() {
@Override
public void mousePressed(MouseEvent e) {
String[] exceptMessages={"NaN", "Infinity"};
Button button = (Button)e.getSource();//获取到点击的按钮对象
String value = button.getLabel();//按钮的值
String expression = display.getText();//获取显示屏的表达式
int len = expression.length();//表达式的长度
switch(value){
case "CE":
display.setText("0");
break;
case "<-":
boolean flag = false;
for(int i=0;i<exceptMessages.length;i++){
if(!expression.equals(exceptMessages[i]))
continue;
flag = true;
break;
}
if(len==1) expression="0";
else if(flag==true){
//存在无穷，NaN等数据
expression="0";
} else if(len>0 && expression.lastIndexOf(" ")!=len-1){
expression=expression.substring(0, len-1);
} else if(len>0 && expression.substring(len-4, len-3).matches("[0-9]+")){
expression = expression.substring(0, len-3);
} else if(len>0){
expression = expression.substring(0, len-2);
}
display.setText(expression);
break;
case "-/+":
case "1/x":
String num = "0";
if(expression.lastIndexOf(" ")!=len-1 && (hasNums(expression, "+")>=1
|| hasNums(expression, "-")>=1 || hasNums(expression, "*")>=1
|| hasNums(expression, "/")>=1)){
//如果输入符号时，前面有别的运算符号，即该运算不是第一个运算， 则只对靠近它的一组数运算
num = expression.substring(expression.lastIndexOf(" "), len);
double number1 = Double.parseDouble(num);
expression = expression.substring(0, expression.lastIndexOf(" "));
if(value.equals("-/+")) {
number1 = 0 - number1;
}else{
number1 = 1/number1;
BigDecimal b = new BigDecimal(number1);
number1 = b.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
}
expression += " " + number1;
}else{//当是第一个运算时
double number1 = Double.parseDouble(expression);
if(value.equals("-/+")) {
number1 = 0 - number1;
}else{
number1 = 1/number1;
BigDecimal b = new BigDecimal(number1);
number1 = b.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
}
expression = "" + number1;
}
display.setText(expression);
break;
case "√":
case "sin":
case "cos":
String number = "0";
if(expression.lastIndexOf(" ")==len-1 && expression.substring(len-2, len-1).equals(")")){
//如果输入符号的前面是右括号，则将其是对该对括号进行运算 如2 + sin ( 5 + 4 )
number = expression.substring(expression.lastIndexOf("("), len);
expression = expression.substring(0, expression.lastIndexOf("("));
expression = expression + value + " " + number;
// System.out.println("one");
}else if(expression.lastIndexOf(" ")!=len-1 && (hasNums(expression, "+")>=1
|| hasNums(expression, "-")>=1 || hasNums(expression, "*")>=1
|| hasNums(expression, "/")>=1)){
//如果输入符号时，前面有别的运算符号，即该运算不是第一个运算， 则只对靠近它的一组数运算
number = expression.substring(expression.lastIndexOf(" "), len);
expression = expression.substring(0, expression.lastIndexOf(" "));
expression += " " + value + " " + "(" + number + " " + ")" + " ";
// System.out.println("two");
}else{//当是第一个运算时
number = expression;
expression = value + " " + "(" + " " + number + " " + ")" + " ";
// System.out.println("three");
}
display.setText(expression);
break;
case "!":
case "^":
case "%":
case "+":
case "-":
case "*":
case "/":
if(expression.lastIndexOf(" ")==len-1 && !expression.substring(len-2, len-1).equals("(")
&& !expression.substring(len-2, len-1).equals(")")){ //如果前面不是括号而是其他符号，则去掉这个符号，变成新的符号
expression = expression.substring(0, len-3);
} else if(len>1 && expression.substring(len-2, len-1).equals("(")){ //如果前面是左括号，则在符号前加上0
expression+="0";
}
expression+=" "+value+" ";
display.setText(expression);
break;
case "(":
case ")":
if(value.equals(")") && hasNums(expression, "(")<=hasNums(expression, ")")) break;
else if(value.equals(")") && expression.lastIndexOf(" ")==len-1 && expression.lastIndexOf("(")!=len-2){
//像2 + ( 5 + 的情况，自动加一个数
expression=autoAdd(expression);
len+=1;
}
if(expression.equals("0")) expression="";
else if(value=="(" && expression.lastIndexOf(" ")!=len-1) expression+=" *";//5*(2+3)默认加一个*号
if(expression.lastIndexOf(" ")==len-1) expression=expression.substring(0, len-1); //清除前面的空格
if(len>1 && value.equals("(") && expression.lastIndexOf(")")==len-2){
//像(a+b)*(c+d) 中间加个*
expression+=" *";
len+=2;
}
expression+=" "+value+" ";
display.setText(expression);
break;
case ".":
if(expression.lastIndexOf(")")!=-1 && expression.lastIndexOf(")")==len-2) expression+="* 0"+value;//括号自动变为*法
else if(expression.lastIndexOf(" ")==len-1) expression+="0"+value;
else if(expression.lastIndexOf(".")!=-1 && expression.lastIndexOf(".")>expression.lastIndexOf(" ")) break;//连续输入2个.
else expression+=value;
display.setText(expression);
break;
case "=":
if(hasNums(expression, "(")>hasNums(expression,")")){
//少了gapNum个括号
expression+=expression.lastIndexOf(" ")==len-1?"+ 0":" + 0";
int gapNum=hasNums(expression,"(")-hasNums(expression,")");
for(int i=0;i<gapNum;i++){
expression+=" ) ";
}
}
else if(expression.lastIndexOf(" ")==len-1 && expression.lastIndexOf(")")!=len-2){
//最后一个为运算符的时候，默认在表达式后加个0或1
expression=autoAdd(expression);
}
cal(expression);
break;
default:
//excptMessages
if(expression.substring(len-1).matches("[a-zA-Z]+")){
expression="0";
}
//数字
if(expression.equals("0")) expression="";
if(expression.lastIndexOf(" ")==len-1 && expression.lastIndexOf(")")==len-2) expression+="* ";
expression+=value;
display.setText(expression);
}
}
});
this.add(button);
}
// 计算
private void cal(String str){
//得到新表达式
LinkedList<String> expre=getNewExpre(str.split(" "));
// for(int i=0;i
// System.out.println(expre.get(i)+",");
// }
// System.out.println();
for(var i=0;i<expre.size();i++){
var val=expre.get(i);
switch(val){
case "-":
case "+":
case "*":
case "/":
case "%":
case "^":
expre.set(i-2,String.valueOf(operation2(expre.get(i-2), expre.get(i-1), val)));
expre.remove(i-1);
expre.remove(i-1);
i-=2;
break;
case "sin":
case "cos":
case "!":
case "√":
// System.out.println("position4" + " " + val);
// System.out.println("position5" + " " + expre);
expre.set(i-1, String.valueOf(operation1(expre.get(i-1), val)));
// System.out.println("position6" + " " + expre);
expre.remove(i);
// System.out.println("position7" + " " + expre);
i-=1;
break;
default:
break;
}
}
String result = expre.get(0);
display.setText(result);//归零
//增加历史记录
String recordStr = record.getText();
if (recordStr.equals(nullMessage)) recordStr = "";
recordStr += str + "=" + result + "\n\n";
record.setText(recordStr);
}
//得到新表达式
private LinkedList<String> getNewExpre(String[] expression){
// for(int i=0;i
// System.out.println(expression[i]+",");
// }
// System.out.println("flag");
LinkedList<String> symbols=new LinkedList<>();//存放符号的栈
LinkedList<String> newExpre=new LinkedList<>();//存放新的表达式的栈
for(int i=0;i<expression.length;i++){
String val=expression[i];
if(val.equals("")) continue;
// System.out.println("position1" + " " + i +" " + symbols);
// System.out.println("position2" + " " + i +" " + newExpre);
switch(val){
case "(":symbols.add(val); break;
case ")":
boolean isOK=true;
while(isOK){
String _symbol=symbols.pollLast();
if(_symbol.equals("(")) isOK=false;
else newExpre.add(_symbol);
};
break;
case "-/+":
case "!":
case "√":
case "sin":
case "cos":
case "^":
case "%":
case "+":
case "-":
case "*":
case "/":
if(symbols.size()==0){//如果符号栈为空，则入栈
symbols.add(val);
} else if(compareSymbols(val,symbols.get(symbols.size()-1))){//如果将入栈比栈顶符号优先级高，则入栈
symbols.add(val);
} else {
while(symbols.size()>0 && !compareSymbols(val,symbols.get(symbols.size()-1))){//否则，全部出栈，直到遇到优先级比自己小的
newExpre.add(symbols.pollLast());
}
symbols.add(val);
}
break;
default:
newExpre.add(val);
}
}
while (symbols.size()>0){
newExpre.add(symbols.pollLast());
}
return newExpre;
}
//比较运算符优先级
private boolean compareSymbols(String newSymbol, String existSymbol){
if(getPriority(newSymbol)>getPriority(existSymbol)){
return true;
}
else{
return false;
}
}
//运算符的优先级
private int getPriority(String string){
int order;
switch(string){
case "+":
case "-":
order = 1;
break;
case "%":
case "*":
case "/":
order = 2;
break;
case "sin":
case "cos":
case "!":
case "^":
case "√":
order = 3;
break;
default:
order = -1;
break;
}
return order;
}
//计算方法
//双目运算
private int open = 0;//判断输入是否正确
private double operation2(String str1, String str2, String str3){
double result=0;
double num1,num2;
num1 = Double.parseDouble(str1);
num2 = Double.parseDouble(str2);
switch (str3){
case "+":
result = num1 + num2;
break;
case "-":
result = num1 - num2;
break;
case "*":
result = num1 * num2;
break;
case "/":
result = num1 / num2;
break;
case "%":
result = num1 % num2;
break;
case "^":
result = Math.pow(num1, num2);
break;
}
return result;
}
//单目运算
private double operation1(String str1, String str2){
double result=0;
double num1;
num1= Double.parseDouble(str1);
switch (str2){
case "sin":
num1 = Math.toRadians(num1);
result = Math.sin(num1);
BigDecimal b = new BigDecimal(result);
result = b.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
break;
case "cos":
num1 = Math.toRadians(num1);
result = Math.cos(num1);
BigDecimal d = new BigDecimal(result);
result = d.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
break;
case "!":
result = Factorial(num1);
break;
case "√":
result = Math.sqrt(num1);
break;
}
// System.out.println("position3" + " " + result);
return result;
}
//阶乘运算
private double Factorial(double number){
if(number==1) return number;
else if(number>1){
return number * Factorial(number-1);
}
return number;
}
//判断str中有多少个val
private int hasNums(String str, String val){
int nums = 0;
while(str.indexOf(val)!=-1){
nums+=1;
str=str.substring(str.indexOf(val)+1);
}
return nums;
}
//表达式常见错误，自动在后面补0或1
private String autoAdd(String expression){
String symbol=expression.substring(expression.length()-2,expression.length()-1);
switch(symbol){
case "+":
case "-":
expression+="0";
break;
case "!":
break;
case "*":
default:
expression+="1";
}
return expression;
}
}