Java dynamically adjusts the size of an array __java

In Java, once an array is created, its size cannot be changed. Therefore, we can change the implementation of the array, dynamically adjust the size of the array, so that all elements can be saved, without wasting space. In fact, it's simple to do this:

private void Resize (int max) {
    //move the stack of size N<max to the size max array
    item[] temp = (item[)) new Object[max];
    for (int i = 0;i < n;i++) {
        temp[i] = A[i];
    }
    A = temp;
}

For example, its application in push, you can dynamically adjust the size of the array:

public void push (item) {
    if (n==a.length) resize (2*a.length);
    a[n++] = Item;
}

Applications in POPs:

Public Item pop () {
    item = A[--n];
    A[N] = null;
    if (n>0 && n==a.length/4) resize (A.LENGTH/2);
    return item;
}