package com.test.custom;

public interface IStack<E> {

     E pop();

     void push(E e);

     E peek();

     int size();

     boolean empty();

     void clear();

}

package com.test.custom;

import java.util.ArrayList;

import java.util.EmptyStackException;

import java.util.List;

public class CustomStack<E> implements IStack<E>{

    List<E> list =new ArrayList<E>();

    @Override

    public E pop() {

        // TODO Auto-generated method stub

        E e = peek();

        list.remove(list.size()-1);

        return e;

    }

    @Override

    public void push(E e) {

        // TODO Auto-generated method stub

        list.add(e);

    }

    @Override

    public E peek() {

        // TODO Auto-generated method stub

        int len = list.size();

        if(len==0){

            throw new EmptyStackException();

        }

        return list.get(len-1);

    }

    @Override

    public int size() {

        // TODO Auto-generated method stub

        return list.size();

    }

    @Override

    public boolean empty() {

        // TODO Auto-generated method stub

        return size()==0;

    }

    @Override

    public void clear() {

        // TODO Auto-generated method stub

        list.clear();

    }

}

package com.test.custom;

public class TestStack {

     public static void main(String[] args) {

        CustomStack<String> stack =new CustomStack<String>();

        for(int i =0 ; i < 4 ; i++){

            stack.push(""+(char)('A'+i));

        }

        System.out.println(stack.peek());

        System.out.println(stack.size());

        System.out.println(stack.pop());

        System.out.println(stack.size());

        System.out.println(stack.peek());

        stack.push("hello");

        System.out.println(stack.size());

        for(int i=0;i<5;i++){

        System.out.println(stack.pop());

        System.out.println(stack.size());

        }

    }

}

package com.test.custom;

public interface IQueue<E> {

     boolean offer(E e); //超过容量就抛出 IllegalStateException

     E peek();//获取列头不移除，队列为null返回null

     E poll(); //获取并且移除列头

     int size();

     boolean isEmpty();

}

package com.test.custom;

import java.util.ArrayList;

import java.util.List;

public class CustomQueue<E> implements IQueue<E>{

    List<E> list =new ArrayList<E>();

    private int size;

    @Override

    public boolean offer(E e) {

        // TODO Auto-generated method stub

        if(list.size()>=size){

            throw new IllegalArgumentException();

        }

        list.add(e);

        return true;

    }

    @Override

    public E peek() {

        // TODO Auto-generated method stub

        if(size() == 0) return null;

        return list.get(0);

    }

    @Override

    public E poll() {

        // TODO Auto-generated method stub

        E e = peek();

        if(size()>0) list.remove(0);

        return e;

    }

    @Override

    public int size() {

        // TODO Auto-generated method stub

        return list.size();

    }

    @Override

    public boolean isEmpty() {

        // TODO Auto-generated method stub

        return list.size()==0;

    }

    public CustomQueue(int size) {

        this.size = size;

    }

}

package com.test.custom;

public class TestQueue {

      public static void main(String[] args) {

          CustomQueue<String> stack =new CustomQueue<String>(4);

          for(int i =0 ; i < 4 ; i++){

              stack.offer(""+(char)('A'+i));

          }

          System.out.println(stack.peek());

          System.out.println(stack.size());

          System.out.println(stack.poll());

          System.out.println(stack.size());

          System.out.println(stack.peek());

          System.out.println(stack.size());

          stack.offer("hello");

          System.out.println(stack.size());

          for(int i=0;i<5;i++){

          System.out.println("i:"+stack.poll());

          }

          for(int i =0 ; i < 5 ; i++){

              stack.offer(""+(char)('A'+i));

          }

      }

}