Question

class Scroll {
    static boolean up;
    static boolean down;
    public static void scroll(boolean direction) {
        if (/* ... */) {
            System.out.println("UP");
        }
        else {
            System.out.println("DOWN");
    }
}

public class Test2 {
    public static void main(String[] args) {
        Scroll.scroll(Scroll.up);
    }
}

How can I check which field has function been called with – with Scroll.up or Scroll.down? I know that in above code I could get same effect in other way, but it’s simplified code with essence of my problem.

Answer 1

If the only choices are up or down, you can rename direction as up and then:

if (up) {
    // Up
}
else {
    // Down
}

If there are more directions (left and right, for instance), or even if not really, this is where enum is handy:

enum Direction {
    Up,
    Down,
    Left,
    Right
}

Then use that in your code, possibly with a switch:

switch (direction) {
    case Direction.Up:
        // ...
        break;
    case Direction.Down:
        // ...
        break;
    case Direction.Left:
        // ...
        break;
    case Direction.Right:
        // ...
        break;
}

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