Java8 using enum values in interface's default methods

Question

I'm exploring possibilities of static and default methods introduced in java 8.

I've an interface that has 2 default methods that do construct a command, that I run on server through ssh to do some simple tasks remotely. Moving mouse requires 2 arguments: x and y position of the mouse.

public interface Robot {

    default String moveMouse(int x, int y) {
        return constructCmd("java -jar move_mouse.jar " + x + " " + y);
    }

    default String clickLeft() {
        return  constructCmd("java -jar click_left.jar");
    }

    static String constructCmd(String cmd) {
        return "export DISPLAY=:1.0\n" +
                "cd Desktop\n" +
                cmd;
    }
} 

I've multiple enums with values preset, I could potently combine all enums into one and not use interface what so ever, however that enum would contain hundreds or thousands of values and I want to keep it somewhat organised, so I've split evertying in multiple enums.

I want all enums to share same methods so I figured I'll give default methods in an interface a shot.

public enum Field implements Robot {

    AGE_FIELD(778, 232),

    NAME_FIELD(662, 280);

    public int x;
    public int y;

    Field(int x, int y) {
        this.x = x;
        this.y = y;
    }
}

So I can get String commands by:

Field.AGE_FIELD.clickLeft();
Field.AGE_FIELD.moveMouse(Field.AGE_FIELD.x, Field.AGE_FIELD.y);

However moveMouse looks really bad to me and I think it should be somehow possible to use enum's values by default.

Anyone has a a nice solution for such problem?

Answer 1

The problem is your architecture. On the one hand, you have a layer that actually executes the mouse-movement (represented by your Robot interface). Now, you need a layer that produces mouse-movement and sends it to a Robot to execute this mouse-movement. Let's call the interface defining this layer MouseTarget (fits your example nicely):

public interface MouseTarget {
    int getTargetX();
    int getTargetY();

    default void moveMouseHere(Robot robot) {
        robot.moveMouse(this.getTargetX(), this.getTargetY());
    }
}

This interface represents one mouse-movement to one target. As you see the moveMouseHere(Robot robot) method expects a Robot to send the movement to (which does the actual work). Now, all what is left is to adapt your Fields enum:

public enum Fields implements MouseTarget {

    AGE_FIELD(778, 232), NAME_FIELD(662, 280);

    public int targetX;
    public int targetY;

    Fields(int targetX, int targetY) {
        this.targetX = targetX;
        this.targetY = targetY;
    }

    @Override
    public int getTargetX() {
        return targetX;
    }

    @Override
    public int getTargetY() {
        return targetY;
    }
}