longest common substring

public int (String A, String B) {
    
    int[][] dp = new int[A.length() + 1][B.length() + 1];
    int max = 0;
    for (int i = 1; i <= A.length(); ++i) {
        for (int j = 1; j <= B.length(); ++j) {
            if (A.charAt(i-1) == B.charAt(j-1)) {
                dp[i][j] = dp[i-1][j-1] + 1;
                max = Math.max(max, dp[i][j]);
            }
        }
    }
    return max;
}