自己实现数据结构系列三---Stack

一.代码部分

1.定义接口

public interface Stack<E> {
    int getSize();
    boolean isEmpty();
    void push(E e);
    E pop();
    E peek();
}

2.基于数组实现：

public class ArrayStack<E> implements Stack<E> {

    ArrayList<E> arrayList;
    public ArrayStack(int capacity){
        arrayList = new ArrayList(capacity);
    }

    public ArrayStack(){
        arrayList = new ArrayList<E>();
    }

    @Override
    public int getSize() {
        return arrayList.getSize();
    }

    @Override
    public boolean isEmpty() {
        return arrayList.isEmpty();
    }

    @Override
    public void push(E e) {
        arrayList.addLast(e);
    }

    @Override
    public E pop() {
        return arrayList.removeLast();
    }

    @Override
    public E peek() {
        return arrayList.get(getSize()-1);
    }

    public int getCapacity(){
        return arrayList.getCapacity();
    }

    @Override
    public String toString() {
        StringBuilder res = new StringBuilder();
        res.append("Stack:");
        res.append("[");
        for (int i = 0; i < arrayList.getSize(); i++) {
            res.append(arrayList.get(i));
            if(i != arrayList.getSize()-1){
                res.append(",");
            }
        }
        res.append("] top");
        return res.toString();
    }
}

3.基于链表实现：

public class LinkedListStack<E> implements Stack<E> {

    private LinkedListPlus<E> list;

    public LinkedListStack(){
        list = new LinkedListPlus<>();
    }

    @Override
    public int getSize() {
        return list.getSize();
    }

    @Override
    public boolean isEmpty() {
        return list.isEmpty();
    }

    @Override
    public void push(E e) {
        list.addFirst(e);
    }

    @Override
    public E pop() {
        return list.removeFirst();
    }

    @Override
    public E peek() {
        return list.getFirst();
    }
　　@Override
　　public String toString() {
    　　StringBuilder res = new StringBuilder();
    　　res.append("stack:top");
    　　res.append(list);
    　　return res.toString();
　　}
}