栈，队列的实现（Java版）

一、栈（先进后出）

public class Stack{
    public int maxsize;
    public int top=-1;
    public String []arr;
    public Stack(int maxsize){
        this.maxsize=maxsize;
        arr=new String[maxsize];
        top=-1;
    }
    public void push(String str){
        arr[++top]=str;
    }
    public String pop(){
        if(!isEmpty()){
         return arr[top--];
        }
        return null;
    }
    public boolean isEmpty(){
      return (top==-1);
    }
    public boolean isFull(){
    return (top==maxsize-1);
    }
    public void clear(){
     top=-1;
    }
    public String peek(){
        return (arr[top]);
    }

}

二、队列（先进先出）

public class Queue {
    private int front;
    private int rear;
    private int maxSize;
    private String arr[];
    private int curNumber;
    public Queue(int maxSize){
        front=0;
        rear=-1;
        curNumber=0;
        this.maxSize=maxSize;
        arr=new String[maxSize];
    }
    public void insert(String str){
        if(rear==maxSize-1)rear=-1;
        arr[++rear]=str;
        curNumber++;
    }
    public String remove(){
        if(front==maxSize-1)
            front=0;
        curNumber--;
        return arr[front++];
    }
    public boolean isEmpty(){
       return (curNumber==0);
    }
    public boolean isFull(){
        return (curNumber==maxSize);
    }
    public int size(){
     return curNumber;
    }
    public String peekFirst(){
        return arr[front];
    }
}