Question

I don’t really know how to describe my issue, so I’ll just show a code example:

int[][][] mat;
int n;
int specificValue;

for (int i = 0; i < n; i++) {
    if(mat[i][n-i][3] != specificValue) {
        doStuff();
    }
}

I’m looking up Integer values in a 3d-array. For each field I have to use one of these:

• a counter running from zero to n
• a counter running from n to zero
• a fixed value

So i’ve tried to build a Method that would save me from writing this for loop about 20 times, but i failed, so that’s where i need help. My idea was something like this:

search(Loop.UP, Loop.DOWN, Loop.FIXED);

where “Loop” would be an enum representing one of my possibilities, but I don’t know how to implement it or if this is even possible in Java without hardcoding every possible combination.

Hope you can help 🙂

---

OK, more specific… with my setup i’m drawing a vector through this 3d-array, a diagonal to be specific and i want to know what values are on this vector and only on this vector.

And because there is more than one possibility to draw such a vector, i’d like to have a more general method to get to the values. My search could just be as simple as

search(Loop.UP, Loop.FIXED, Loop.FIXED);   // one plane

which would be a simple for-loop with one counter, but also

search(Loop.DOWN, Loop.UP, Loop.UP);   // through all three planes

Answer 1

Path pathX = new Path.Up();
Path pathY = new Path.Down(n);
Path pathZ = new Path.Fixed(3);

for (int i = 0; i < n; i++) {
    if(mat[pathX.pos(i)][pathY.pos(i)][pathZ.pos(i)] != specificValue) {
        doStuff();  
    }
}

where

public interface Path {
    public int pos(int i);

    public static class Up implements Path {
         @Override public int pos(int i) { return i; }
    }

    public static class Down implements Path {
         private int n;
         public Down(int n) { this.n = n; }
         @Override public int pos(int i) { return n - i - 1; }
    }

    public static class Fixed implements Path {
         private int v;
         public Down(int v) { this.v = v; }
         @Override public int pos(int i) { return v; }
    }

I didn’t use an Enum because Down depends on n and Fixed on some value.