Thread: Trouble with getX() and getY()

Hi all,

I'm new to programming and am trying to understand getX() and getY() to extract the x, y coordinates from a point entered by the user. One of my problems is that I've defined that point (location) as a double, and so I'm getting the error 'double cannot be dereferenced' when I call location.getX() and location.getY(). To clarify, the x, y is a point of 2 integers.

This program is supposed to take the name, direction, and location of a robot and depending on the user cmd's, it's supposed to move it forward one step, turn it left (N,S,W,E), and print a report saying what was done.

I'd appreciate any clarification so I can test the code I've got. Thanks in advance

import java.util.*;
 
class Robot {
  //method main gets the values from the user
  public static void main(String[] args) {
    Scanner zip = new Scanner(System.in);
    System.out.println("Enter the robot's name: ");
    String name = zip.nextLine();
    System.out.println("Enter the location (x, y) format: ");
    double location = zip.nextDouble();
    System.out.println("Enter the direction the robot is facing: ");
    String direction = zip.nextLine();
    double x = location.getX();
    double y = location.getY();
 
  }
  //method turnLeft changes the direction depending on the currentLocation
  String turnLeft(String direction) { 
    String currentLocation = direction;
    if (currentLocation == "North") {
      currentLocation = "West"; }
    if (currentLocation == "West") {
      currentLocation = "South"; }
    if (currentLocation == "South") {
      currentLocation = "East"; }
    if (currentLocation == "East") {
      currentLocation = "North"; }
  }
  //method moveForward changes the location depending on the currentLocation
  String moveForward(String direction, Double location) { 
    String currentLocation = direction;
    if (currentLocation == "South") {
      location.getY() = location.get(Y) + 1; }
    if (currentLocation == "West") {
      location.getX() = location.getX() - 1; }
  }
  //method report prints the following: 
  String report(String direction, Double location) {
    return name + ", " + location.getX() + ", " + location.getY() + ", " + currentLocation; 
 
  }
}

I can't find a getX() method for the primitive type double.

Also, I wonder if it's an integer/double mixup.

Am looking at it now.

Yep, confirmed that there's no Double method called getX().

Just tried it in a test sample and got the "double cannot be dereferenced" thing too.

Do you know what the input should be in the (x, y) form so that I can use getX()?

I tried changing it to integer but the input is not just one integer, it's a pair of integers.

Well, you could just ask the user for an x value, store it, then ask for a y value and store it.

Also, your moveForeward() and turnLeft() methods should probably be void methods according to the comments before the methods.

The method isn't returning any value though you have set the return type for them as a void.

This has nothing really to do with the point thing, but I just noticed it.

Also, you can use double values as input, just so long as you use two of them.

I'm working on the code right now to fix it.

I've gotten it this far, though I've no idea what you plan to do with the variable currentLocation;

As it is, it will compile, but nothing in the direction will change.

I can't get any further unless I know what to do with currentLocation.

I've gotten rid of all, I think, scope problems.

However, the currentLocation thing had been going out of scope so I tweaked a few things but don't think I solved the problem as I don't know what you intended to do with that variable. Is it the old location or the new one?

    import java.util.*;
 
   class Robot {
      static double locationX, locationY;
      static String name;
      static String direction;
 
 
 
 
   //method main gets the values from the user
      public static void main(String[] args) {
         Scanner zip = new Scanner(System.in);
         System.out.println("Enter the robot's name: ");
         name = zip.nextLine();
         setName(name);
         System.out.println("Enter the direction the robot is facing: ");
          direction = zip.nextLine();
         setDirection(direction);
         System.out.println("Enter the location (x, y) format: ");
         locationX = zip.nextDouble();
         locationY = zip.nextDouble();
         setLocationX(locationX);
         setLocationY(locationY);
 
 
         moveForward(direction);
         turnLeft(direction);
 
         System.out.println(report(direction));
         System.out.println(direction);
 
 
      }
   //method turnLeft changes the direction depending on the currentLocation
      static String turnLeft(String direction) { 
         String currentLocation = direction;
         if (currentLocation.equals ("North")) {
            currentLocation = "West"; }
         else if (currentLocation.equals("West")) {
            currentLocation = "South"; }
         else  if (currentLocation.equals("South")) {
            currentLocation = "East"; }
         else {
            currentLocation = "North"; }
         return currentLocation;
      }
   //method moveForward changes the location depending on the currentLocation
      static String moveForward(String direction) { 
         String currentLocation = direction;
         if (currentLocation.equals("South") ){
            setLocationY( getLocationY() + 1); }
         if (currentLocation.equals("West")) {
            setLocationX(getLocationX() - 1); }
         return currentLocation;
 
      }
   //method report prints the following: 
      static  String report(String direction) {
         String str =     getName() + ", " + getLocationX() + ", " + getLocationY() + ", " + moveForward(direction); 
         return (str);
      }
 
      public static void setName(String name2)
      {
         name = name2;
      }
 
      public static String getName()
      {
         return name;
      }
 
      public static void setLocationX(double locationX2)
      {
         locationX = locationX2;
      }
 
      public static double getLocationX()
      {
         return locationX;
      }
 
      public static void setLocationY(double locationY2)
      {
         locationY = locationY2;
      }
 
      public static double getLocationY()
      {
         return locationY;
      }
 
      public static void setDirection(String direction2)
      {
         direction = direction2;
      }
 
      public static String getDirection()
      {
         return direction;
      }
   }

The first change you should make with your code is to remove all of the static modifiers but the one needed on the main method. You are giving poor advice with this code.

Thanks for all the points. I am not going to use your code, but I understand where you were going with it!

currentLocation starts off being the direction that's entered (North, south, east, west). Let's say the user creates a robot named Joe and enters the direction as South, and the location as 1, 3. If the user inputs the cmd j.turnLeft .. the program will take the direction South, and change the current location to east. then if the person says j.turnLeft again, the current location will be east, and the program will change that to north.

Is setDirection and setLocation a command? We haven't learned that yet so I can't use it, but I am just curious.

Also, another thing I tried was to make the location input a string. then I tried to parse it into an integer which didn't work, but I was wondering if I could parse just the integers from it and use the getX() and getY() procedures there. Since we haven't learned set, I am wondering how it's possible to get the x and y out of the input: x, y.

Is setDirection and setLocation a command?

They look like the names of methods.
I usually think of commands as the name of an executable program that you want the OS to execute.
Hence the term: command line

how it's possible to get the x and y out of the input: x, y.

The String class has a method that will split that String into two Strings: x and y in an array.
Then you could use the Integer class to convert those two Strings into int values.