stackslinked.java

来自「数据结构与算法」· Java 代码 · 共 50 行

package dsa.adt;

import dsa.adt.Stack;
import dsa.exception.StackEmptyException;

public class StackSLinked implements Stack {
	
	private SLNode top;	//链表首结点引用
	private int size;	//栈的大小
	
	public StackSLinked() {
		top = null;
		size = 0;
	}

	//返回堆栈的大小
	public int getSize() {
		return size;
	}

	//判断堆栈是否为空
	public boolean isEmpty() {
		return size==0;
	}

	//数据元素e入栈
	public void push(Object e) {
		SLNode q = new SLNode(e,top);
		top = q;
		size++;
	}

	//栈顶元素出栈
	public Object pop() throws StackEmptyException {
		if (size<1)
			throw new StackEmptyException("错误，堆栈为空。");
		Object obj = top.getData();
		top = top.getNext();
		size--;
		return obj;
	}

	//取栈顶元素
	public Object peek() throws StackEmptyException {
		if (size<1)
			throw new StackEmptyException("错误，堆栈为空。");
		return top.getData();
	}
}