（集合）LInkedList---队列与栈

 

LinkedList提供了addFirst(),addLast(),removeFirst()方法操作集合中的元素

基于这些功能，就可以实现队列与栈的数据结构。

 

队列---先进先出FIFO

 

 

import java.util.Collection;
import java.util.LinkedList;


public class Queue<E> {
	private LinkedList<E> link;
	
	Queue() {
		link = new LinkedList<E>();
	}
	
	public void add(E e) {
		link.addLast(e);
	}
	
	public void addAll(Collection<? extends E> coll) {
		link.addAll(coll);
	}
	
	public E getNext() {
		return link.removeFirst();
	}
	
	public boolean isEmpty() {
		return link.isEmpty();
	}
}

 

 

	public static void main(String[] args) {
		
		List<String> list = new ArrayList<String>();
		list.add("123");
		list.add("abc");
		list.add("000");
		
		printQueue(list);
		
	}



	private static void printQueue(List<String> list) {
		Queue<String> queue = new Queue<String>();
		queue.add("------------");
		queue.addAll(list);
		queue.add("$$$$$$$$$$$$");
		
		while(!queue.isEmpty()) {
			System.out.println(queue.getNext());
		}
	}

 结果

------------
123
abc
000
$$$$$$$$$$$$

 

 

栈---后进先出FILO

 

import java.util.Collection;
import java.util.LinkedList;


public class Stack<E> {
	private LinkedList<E> link;
	
	public Stack() {
		link = new LinkedList<E>();
	}
	
	public void add(E e) {
		link.addFirst(e);
	}

	public void addAll(Collection<? extends E> coll) {
		Object[] elements = coll.toArray();
		int size = elements.length;
		for(int index=size-1;index>=0;index--)
			add((E)elements[index]);
	}
	
	public E getNext() {
		return link.removeFirst();
	}
	
	public boolean isEmpty() {
		return link.isEmpty();
	}
}

 

	public static void main(String[] args) {
		
		List<String> list = new ArrayList<String>();
		list.add("123");
		list.add("abc");
		list.add("000");
		
		printStack(list);
		
	}

	public static void printStack(List<String> list) {
		Stack<String> stack = new Stack<String>();
		stack.add("------------");
		stack.addAll(list);
		stack.add("$$$$$$$$$$$$");
		while(!stack.isEmpty()) {
			System.out.println(stack.getNext());
		}
	}

 结果

$$$$$$$$$$$$
123
abc
000
------------