Java: Help Writing a Program that will Move an object on the screen

Hi guys this is my 1st question so please excuse me if I fail to relay any key details. That being said, I must write a code that will move a turtle on the screen using objects given to us in class. I am currently having trouble with the user inputted string and am having trouble conceptualizing how I will move the turtle without opening a new window.

import java.awt.Color;
import java.util.Scanner;
public class Assignment7 {
public static void main (String[] args){

    World timsWorld = new World (800,800);
    int x = 400, y=100;
    Turtle franklin = new Turtle (x,y,timsWorld);
    while (true){


        String direction;
        Scanner input = new Scanner(System.in);

        System.out.println("please enter direction to move - left (l), right (r), or forward (f)");

        direction = input.next();
        if (direction == "left"){
            x=x-50;
            }
        else if (direction == "right"){
            x=x+50;
        }
        else if (direction == "forward") {
            y=y-50;
        }
        else {
            System.out.println("invalid input");
        }