java 栈实现

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/Wastematerial/article/details/81988181

栈---先进后出的数据结构，与队列相反。

package aobi.com.task;

public class StackByBianca <E>{
	
	private Object[] stack = null;
	private int top = -1;
	private int maxTop = 0;
	
	StackByBianca(){
		this(10);
	}
	StackByBianca(int initSize){
		
		if(initSize > 0){
			this.maxTop = initSize;
			stack = new Object [initSize];
			top = -1;
		}else{
			 throw new RuntimeException("初始化大小不能小于0：" + initSize);
		}
	}
	
	public boolean isEmpty(){
		return top == -1 ? true:false;
	}
	
	public boolean push(E e){
		if(top == maxTop-1)
			expansionStack();//扩栈
		stack[++top] = e;
		return true;
	}
	
	
	public E pop(){
		if(isEmpty())
			throw new RuntimeException("栈为空！");
		return (E) stack[top--];
	}
	
	public E peek(){
		if(isEmpty())
			throw new RuntimeException("栈为空！");
		return (E) stack[top];
	}
	
	public int search(E e){
		int i = top;
		while(i >= 0){
			if(stack[i] == e)
				break;
			i--;
		}
		return i+1;
	}
	
	private void expansionStack(){
		Object [] newStack = new Object [maxTop+10];
		int newTop = -1;
		while(isEmpty()){
			newStack[++newTop]=pop();
		}
		this.stack = newStack;	
		this.maxTop+=10;
	}
	
}