Push an item onto the end of array in Java
Is this really needed?

int[] newArray = (int[]) Array.newInstance(oldArray.getClass().getComponentType(), len + 1);


I would do something like:

public static int[] arrayIntPush(int item, int[] oldArray) {
    int len = oldArray.length;
    int[] newArray = new int[len+1];
    System.arraycopy(oldArray, 0, newArray, 0, len);
    newArray[len] = item;

    return newArray;
}


So for an array of length 10 you make a new array or length 11, copy all existing data into it and then assign the last index to the item.