[FIXED] How to shorten (format) String output properly?

Issue

Simple questions as a beginner making big problems.

I want to shorten (format) a String to only show 1 decimal or 2. Unlucky it is a String not a double.

String getNumber = "6.000m";

I know there is a printf() function but as far I learned it is to print multiple string in a proper order.

How can I make the output to be with only one decimal or if it has more numbers which aren't 0?

6.000 m --> 6.0
4.900 m --> 4.9
4.750 m --> 4.75

Solution

I assume it is always "m" at the end with some optional whitespace in front of it. So I remove it first using a regex. DecimalFormat is your friend to do the rest:

import java.text.DecimalFormat;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Ff {
    static Pattern numberPart=Pattern.compile("([0-9.]*)\\b*m");
    static DecimalFormat df=new DecimalFormat("0.0#####");

    public static String format(String input)
    {
        Matcher m=numberPart.matcher(input);
        if(m.matches())
        {
            return df.format(Double.parseDouble(m.group(1)));
        }
        return null;
    }
    public static void main(String args[]) {
        System.out.println(format("6.000m"));
        System.out.println(format("4.900m"));
        System.out.println(format("4.750m"));
    }
}

and the output is:

6.0
4.9
4.75

Answered By - Conffusion

Answer Checked By - Pedro (PHPFixing Volunteer)