JAVA本身實現List接口Stack

---

---

package 集合.Stack;

import java.util.Arrays;
import java.util.EmptyStackException;
import java.util.Vector;

public class MyStack {
    //底層數組默認長度爲10
    private Object[] myStack = new Object[10];
    //size
    private int size = 0;

    public MyStack() {

    }

    //push
    public Object push(Object obj) {
        //先判斷是否須要擴容
        if(size>=myStack.length){
            myStack = Arrays.copyOf(myStack,myStack.length*2);
        }
        //添加元素
        myStack[size++] = obj;
        //size++;
        return obj;
    }

    //pop彈出棧頂元素
    public Object pop() {
        Object obj = peek();
        //忽略棧頂元素
        size--;
        return obj;
    }

    //peek查找棧頂元素
    public Object peek() {
        if(empty()){
           throw new EmptyStackException();
        }
        return myStack[size - 1];
    }

    //empty判斷棧是否爲空
    public boolean empty() {
        return size == 0;
    }

    //search查找棧中第一齣線的元素
    public int  search(Object obj) {
        for(int i = size -1,j=1;i>=0;i--,j++){
            if(myStack[i] == obj||myStack[i]!=null&&myStack[i].equals(obj)){
                return  j;
            }
        }
        return -1;
    }

    @Override
    public String toString() {
        Object[] strstack = new Object[size];
        System.arraycopy(myStack,0,strstack,0,size);
        for(int i=size-1;i>=size/2;i--){
            Object temp = strstack[i];
            strstack[i] = strstack[size-i-1];
            strstack[size-i-1] = temp;
        }

        return Arrays.toString(strstack);
    }
}