4 java顺序栈实现

package com.java.datastructure.stact;
//java顺序栈实现
public class LinearStact {
    private int top = -1;
    private final static   int defSize = 2;
    private String[] data = new String [defSize];

    //添加元素
    public boolean push(String pData) {
        //判断是否栈满
        if(top+1 >=data.length) {
            //增加容量
            resize();
        }
        ++top;
        data[top] = pData;
        return true;
    }

    //取出元素
    public String pop() {
        //判断是否栈满
        if(isEmpt()) {
            return null;
        }
       String temp = data[top];
        data[top] = null;
        top--;
        return temp;
    }

    //删除元素
    public boolean del() {
        if(isEmpt()) {
            return false;
        }
        data[top] = null;
        top--;
        return true;
    }

    //获取栈顶元素
    public String peek() {
        if(isEmpt()) {
            return null;
        } else {
            return data[top];
        }
    }

    //查找元素
    public int search(String content) {
            int index = -1;
            for (int i=0; i<length(); i++) {
                    if(data[i].equals(content)) {
                        index = i;
                        break;
                    }
            }
            return index;
    }

    public void resize() {
        String[] dataTemp = new String [data.length*2];
        for (int i=0; i<data.length; i++) {
            dataTemp [i] = data[i];
            data[i] = null;
        }
        data = dataTemp;
        dataTemp = null;
    }

    //判断是否为空
    public boolean isEmpt() {
        return top==-1;
    }

    //获取栈宽度
    public int length() {
        return top+1;
    }

    //清除
    public void clean() {
        for (int i=0; i<data.length; i++) {
             data[i] = null;
        }
        top = -1;
    }

    public void display() {
        for (int i=0; i<top+1; i++) {
           System.out.println("打印每个元素"+data[i]);
        }
    }

    public static  void main(String[] args)  {
        LinearStact stact = new LinearStact();
        String content = "isNull  ";
        System.out.println(content+"判断是否为空  "+stact.isEmpt());
        System.out.println(content+"获取栈顶元素  "+stact.pop());
        System.out.println(content+"获取元素个数  "+stact.length());
        System.out.println(content+"获取栈顶-peak元素  "+stact.peek());
        System.out.println(content+"获取查找stactA元素  "+stact.search("stactA"));



        stact.push("stactA");
        stact.push("stactB");
        stact.push("stactC");

        //打印
        stact.display();

        content = "notNull  ";
        System.out.println(content+"判断是否为空  "+stact.isEmpt());
        System.out.println(content+"获取元素个数  "+stact.length());
        System.out.println(content+"获取栈顶-peak元素  "+stact.peek());
        System.out.println(content+"获取栈顶查找stactC元素  "+stact.search("stactC"));
        System.out.println(content+"获取栈顶元素  "+stact.pop());


    }
}