Question

What’s a more efficient way of writing this method:

static Foo[][] copy2D(Foo[][] in)
{
    Foo[][] ret = new Foo[in.length][in[0].length];
    for(int i = 0;i < in.length;i++) {
        for(int j = 0;j < in[0].length;j++) {
            ret[i][j] = in[i][j].clone();
        }
    }
    return ret;
}

Answer 1

If you did not have the clone() you could replace the inner for with:

System.arraycopy( in[i], 0, ret[i], 0, in[0].length );

But since you’re creating a new object in your innermost loop I don’t see any other way to do it.