java 程序，通过scanner 编写计算器

Posted 2020-08-15 强壮的杰克

package test;

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

class Calculator {
    private Double num1;
    private Double num2;
    private String var;
    private  Scanner input;
    
    public Double getNum1() {
        return num1;
    }
    public void setNum1(Double num1) {
        this.num1 = num1;
    }
    public Double getNum2() {
        return num2;
    }
    public void setNum2(Double num2) {
        this.num2 = num2;
    }
    public String getVar() {
        return var;
    }
    public void setVar(String var) {
        this.var = var;
    }
    public Scanner getInput() {
        return input;
    }
    public void setInput(Scanner input) {
        this.input = input;
    }
    public boolean input1(){
            System.out.println("请输入第一个数字");
            String num1Str = input.next();
            if(!this.isNumber(num1Str)){
                input1();
            }else{
                this.num1 =Double.valueOf(num1Str);
            }
            return true;
            
    }
    public boolean input2(){
        System.out.println("输入第二个数:");
        String num2Str = input.next();
        if(!this.isNumber(num2Str)){
            input2();
        }else if(var.equalsIgnoreCase("/")&&num2Str.equalsIgnoreCase("0")){
            System.err.println("除数不能为0");
            input2();
        }else{
            this.num2 =Double.valueOf(num2Str);
        }
        return true;
    }
    public boolean inputVar(){
        System.out.println("输入计算符号:+ - * /");
        String varStr=input.next();

         Pattern pat=Pattern.compile("[+-\\\\*/]");
         Matcher match=pat.matcher(varStr);
         boolean flag=match.matches();
         if(flag==false){
             System.err.println("运算符号不正确！");
             inputVar();
         }else{
             this.setVar(varStr);
         }
         
        return true;
    }
    
    public void goCal(){
        
        Scanner input= new Scanner(System.in);
        this.setInput(input);
        boolean flag1=this.input1();
        if(flag1){
            if(this.inputVar()){
                if(this.input2()){
                    calculate();
                }
            }
        }
    }
    public void calculate(){
        try {
            switch (var) {
            case "+":
                System.out.println(num1+"+"+num2+"="+(num1+num2));
                break;
            case "-":
                 System.out.println(num1+"-"+num2+"="+(num1-num2));
                break;
            case "*":
                 System.out.println(num1+"-"+num2+"="+(num1*num2));
                break;
            case "/":
                System.out.println(num1+"/"+num2+"="+(num1/(double)num2));
                break;

            default:
                break;
            }
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            if(input!=null){
                input.close();
                System.exit(0);
            }
        }
        if(input!=null){
            input.close();
            System.exit(0);
        }
       
    }
    public boolean isNumber(Object obj){
        if(obj==null||obj.toString().equals("")){
            return false;
        }
        Pattern pattern=Pattern.compile("[0-9]+.*[0-9]*");
        String str=obj.toString();
        Matcher matcher=pattern.matcher(str);
        boolean flag=matcher.matches();
        if(flag==false){
            System.err.println("请输入有效数值！");
        }
        return flag;
    }
}



public class TestB {
    
    public static void main(String[] args) {
        Calculator cal = new Calculator();
        cal.goCal();
        
        
    }

}