Хора, знае ли някой каква е грешката в този код? Джъдж дава 12/100.

package com.company;
import java.util.Scanner;
public class CMconverter {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter size: ");
        double size = Double.parseDouble(scanner.nextLine());
        String sourceMetric = scanner.nextLine();
        String destMetric = scanner.nextLine();
        if (sourceMetric == "km") {
            size = size / 0.001;
        }else if (sourceMetric == "cm") {
            size = size / 100.0;
        }else if (sourceMetric == "mm") {
            size = size / 1000.0;
        }else if (sourceMetric == "ft") {
            size = size / 3.2808399;
        }else if (sourceMetric == "yd") {
            size = size / 1.0936133;
        }else if (sourceMetric == "in") {
            size = size / 39.3700787;
        }else if (sourceMetric == "mi") {
            size = size / 0.000621371192;
        }
      if (destMetric == "km") {
          size = size * 0.001;
      }else if (destMetric == "cm") {
          size = size * 100.0;
      }else if (destMetric == "mm") {
          size = size * 1000.0;
      }else if (destMetric == "ft") {
          size = size * 3.2808399;
      }else if (destMetric == "yd") {
          size = size * 1.0936133;
      }else if (destMetric == "in") {
          size = size * 39.3700787;
      }else if (destMetric == "mi") {
          size = size * 0.000621371192;
      }
        System.out.println(size + " " + destMetric);
    }
}