Question

I have two SQL tables. After grabbing both tables in ResultSets, I’ve stored them in String[][]s, ordered by a common id column. These tables should contain the same data, however one may have duplicates of the same row from the other. In order to check if every String[] in table A is present at least once in table B, I need to construct a somewhat efficient contains()-esque method for String[].

This is what I have so far, but am stumped (also not sure if there’s a much more efficient solution). Give it the source table and target table. It takes each String[] in the source table and (should) go through each String[] in the target table and find an instance of the source String[] somewhere in the target String[][] by checking if there’s at least one String[] that matches the original String[], element by element. Can anyone point me in the right direction and/or fill in the blanks? This isn’t homework or any assignment, I’m refactoring some code and am having a major brain fart. Thanks!

    public boolean targetContainsSource(String[][] s, String[][] t) {
    boolean result = true;

    //For each String[] in String[][] s
    for (int i = 0; i < s.length; i++) {

        //For each String[] in String[][] t
        for (int j = 0; j < t.length; j++) {

            //For each String in t's String[]
            for (int k = 0; k < t[0].length; k++) {
                if (!s[i][k].equals(t[j][k])) {

                }
            }
        }
    }

    return result;
}

Answer 1

Your innermost loop could be removed by using Arrays.equals().

For each element of the first array, you should define a found boolean variable, that would only be set to true once the element is found in the second array. Once the second loop is finished, if this variable is still false, you have found an element of the first array that is not in the second, and you can return immediately.

And of course, as soon as this variable is set to true, you can break out of the second loop.