How does this java code work?

public static void main(String[] args)

public static void main(String[] args)
{
    int [][]shatner = new int[1][1];
    int []rat = new int[4];
    shatner[0] = rat;
    System.out.println(shatner[0][3]);
}

Surprisingly, the output is 0. Why doesn't Java check for this indexoutofbound error?

Solution

Don't be surprised Shatner [0] is an array (rat) with a length of exactly 4 So shartner [0] [3] is rat [3], which happens to be 0