数据结构栈的定义（java）

定义栈的接口

public interface IStack<E> {    E push(E item);     //入栈    E pop();            //出栈    E peek();           //取栈顶元素    int size();         //返回栈中元素的个数    boolean empty();    //判断栈是否为空}

实现接口

import java.lang.reflect.Array;public class SeqStack<E> implements IStack<E> {    private int maxsize;       private int top;    private E[] data;    public SeqStack(Class <E> type,int maxsize){        this.maxsize=maxsize;        top=-1;   //栈为空top为-1        data = (E[])Array.newInstance(type, maxsize);    }   //入栈    public E push(E item) {        if(!isfull()){            data[++top]=item;            return item;        }        else            return null;    }    //取出栈顶数据    public E pop() {        if(!empty())            return data[top--];        else                return null;    }    public E peek() {        if(!empty()){            return data[top];        }        else            return null;    }    public int size() {        return top+1;    }    public boolean empty() {        if(top==-1)            return true;        else            return false;    }    public boolean isfull(){        if(top==maxsize-1)            return true;        else            return false;    }}