How do I rewrite this double for loop with a an if else using Java 8 lambdas?

Question

I am trying to rewrite this piece of code using Java 8 lambdas. But so far, I couldn't think of any way to handle if and else together.

for (int i = 0; i<= m; i++)
    {
      for (int j = 0; j <=n ; j++)
      {
        if (i == 0 || j == 0)
          L[i][j] = 0;

        else if (X.charAt(i-1) == Y.charAt(j-1))
          L[i][j] = L[i-1][j-1] + 1;

        else
          L[i][j] = Math.max(L[i-1][j], L[i][j-1]);
      }
    }

Answer 1

Turning your code into a lambda:

Runnable lambda = () -> {
    for (int i = 0; i <= m; i++) {
        for (int j = 0; j <= n; j++) {
            if (i == 0 || j == 0)
                L[i][j] = 0;
            else if (X.charAt(i-1) == Y.charAt(j-1))
                L[i][j] = L[i-1][j-1] + 1;
            else
                L[i][j] = Math.max(L[i-1][j], L[i][j-1]);
        }
    }
};
lambda.run();

Oh, you meant streams with lambdas?

IntStream.rangeClosed(0, m).forEachOrdered(i -> {
    IntStream.rangeClosed(0, n).forEachOrdered(j -> {
        if (i == 0 || j == 0)
            L[i][j] = 0;
        else if (X.charAt(i-1) == Y.charAt(j-1))
            L[i][j] = L[i-1][j-1] + 1;
        else
            L[i][j] = Math.max(L[i-1][j], L[i][j-1]);
    });
});

Oh, you don't want lambda {} blocks ?

IntStream.rangeClosed(0, m).forEachOrdered(i ->
    IntStream.rangeClosed(0, n).forEachOrdered(j ->
        L[i][j] = (i == 0 || j == 0 ? 0
                   : X.charAt(i-1) == Y.charAt(j-1) ? L[i-1][j-1] + 1
                   : Math.max(L[i-1][j], L[i][j-1]))
    )
);

Not that I see the point of doing any of it.