MUST BE DONE IN NETBEANS JAVA

5. (20 points) ArrayStack class represents array implementation of the Stack. Provided class has four methods that are not implemented: push(T newEntry), peek(), clear() and pop(). Complete the implementation of these methods. /** Task: Retrieves the stack's top entry. * @return either the object at the top of the stack or null if * the stack is empty */ public T peek() { public class ArrayStack implements Stackinterface { private T[] stack; // array of stack entries private int toplndex; // index of top entry private boolean initialized = false; private static final int DEFAULT_INITIAL_CAPACITY = 50; private static final int MAX_CAPACITY = 10000; } /** Task: Removes all entries from the stack */ public void clear() { public ArrayStack() { this(DEFAULT_INITIAL_CAPACITY); } } public ArrayStack(int initialCapacity) { checkCapacity(initialCapacity); @ SuppressWarnings("unchecked") T[] tempStack = (T[])new Object[initialCapacity]; stack = tempStack; toplndex = -1; initialized = true; } // end constructor //adds a new entry to the top of the stack public void push(T newEntry) { public void ensureCapacity(){ if (toplndex == stack.length-1) {// if array is full, expand array int newLength = 2 * stack.length; checkCapacity(newLength); Arrays.copyOf(stack, newLength); } } //check if there is enough capacity, if not throw an exception public void checkCapacity(int capacityLength) { if (MAX_CAPACITY