For example, giving two arrays below:
int[] array1={80,103,142,91,160,250,7,7,7,7};
int[] array2={130,105,209,7,7,7,7};
except {7,7,7,7}, the numbers in the array are some random numbers which between 0 and 255.

Code:

    public static int hashCode(int[] array) {
        int total = 0;
        for (int element : array) {
            total = total * 256;
            total = total + element;
        }
        return total;
    }

    public static void main(String[] args) {
    int[] array1 = {80, 103, 142, 91, 160, 250, 7, 7, 7, 7};
    int[] array2 = {130, 105, 209, 7, 7, 7, 7};
    int hashCode1 = hashCode(array1);
    int hashCode2 = hashCode(array2);
    System.out.println("hashCode1: " + hashCode1);//117901063
    System.out.println("hashCode2: " + hashCode2);//117901063

    }

Adding the number of arrays from 2 to 100, as you append {7,7,7,7} at the end of the arrays, they still have the same hashCode.(Append {1,2,3,4} have the same effect)

Question: Why append several numbers at the end of the arrays, will cause they have the same hashCode?

I try to view the values in the debugger, but I still did not understand. Thanks in advance:)

Originally this question is from CS61B Spring 2018 HW3, it is asking to write a test to prove the provided hashCode function has poor distribution.
One way to complete this task is to append several numbers(e.g. {7,7,7,7}) at the end of the arrays.

What I've tried and what I've observed：

1. make 100 arrays from {some random numbers,7,7,7,7,7,7,7} to
   {some random numbers,7}

Result: there are some arrays that have different hashCodes, but there are still too many arrays that have the same hashCode

2. make 100 arrays from {some random numbers,7,7,7,7} to
   {7,7,7,7,some random numbers}

Result: there are some arrays that have different hashCode, but there are still too many arrays that have the same hashCodes

3. make 100 arrays from {some random numbers,7,7,7,7} to
   {a random number,7, a random number,7, a random number,7}

Result: the distribution is good, there are not too many arrays that have the same hashcode