CC3.5.java

/*3.5 Implement a MyQueue class which implements a queue using two stacks.*/
public class MyQueue<T> {
    Stack<T> stackNewest, stackOldest;
    public MyQueue() {
        stackNewest = new Stack<T>();
        stackOldest = new Stack<T>();
    }
    public int size() {
        return stackNewest.size()+stackOldest.size();
    }
    public void add(T value) {
        stackNewest.push(value);
    }
    private void shiftStacks() {
        if(stackOldest.isEmpty()) {
            while(!stackNewest.isEmpty()) {
                stackOldest.push(stackNewest.pop());
            }
        }
    }
    public T peek() {
        shiftStack();
        return stackOldest.peek();
    }
    public T remove() {
        shiftStacks();
        return stackOldest.pop();
    }
}