如何限制小数位数？

Question

I am doing a basic calculator using double, but I wanted the output to limit on showing only 2 decimal digits.

For example, when this is the input:

5 + 0.70

I wanted the output to be:

5.70

So how to do it so it always shows 2 decimal digits? Below is my code:

import java.util.Scanner;

class Main{

public static void main(String[] args) {

    Scanner input=new Scanner(System.in);
    
    double fnum,snum,ans;
    char sign; 
    

    fnum=input.nextDouble();
    sign=input.next().charAt(0); 
    snum=input.nextDouble();
    
    if (sign == '+' ){
        ans=fnum + snum;
        System.out.println(ans);
    }
    else if(sign == '-')
    {
        ans=fnum-snum;
        System.out.println(ans);
    }
    else if(sign == '/'){
            ans=fnum/snum;
            System.out.println(ans);
    }
    else if(sign == '*'){
                ans=fnum*snum;
                System.out.println(ans);
    }
    else
        
    System.out.println("Your Input is not correct,please check it for any error(s).");
        
}

}

Answer 1

Just use String.format:

System.out.println(String.format("%.2f",ans));

Note that this converts your value into a String, for calculations you should keep using its numeric representation.