java数据结构之栈

1，栈接口

package pku.ss.datastructure.IStackLi;

public interface IStackLi {
	/**
	 * Get the size of the stack
	 * @return size of the stack
	 */
	public int getSize();
	/**
	 * Judge that if the stack is full
	 * @return true or false
	 */
	public boolean isFull();
	/**
	 * Judge that if the stack is empty
	 * @return true or false
	 */
	public boolean isEmpty();
	/**
	 * Set the stack to be empty
	 */
	public void makeEmpty();
	/**
	 * Push a element x into stack, if the operation is right then return true,
	 * else return false
	 * @param x
	 * @return true or false
	 */
	public boolean push(Object x);
	/**
	 * return the top element of the stack
	 * @return the top element
	 */
	public Object top();
	/**
	 * Pop the top element from the stack, if the operation is right, then return 
	 * true, else return false
	 * @return true or false
	 */
	public boolean pop();
	
}

2，栈的实现

package pku.ss.datastructure.StackLi;

import pku.ss.datastructure.IStackLi.IStackLi;

public class StackLi implements IStackLi {
	private int maxSize;
	private int size;
	private ListNode topOfStack;

	public StackLi(int maxSize) {
		this.maxSize = maxSize;
		size = 0;
		topOfStack = null;
	}

	@Override
	public int getSize() {
		return this.size;
	}

	@Override
	public boolean isEmpty() {
		return size == 0;
	}

	@Override
	public boolean isFull() {
		return size > maxSize - 1;
	}

	@Override
	public void makeEmpty() {
		size = 0;
		topOfStack = null;
	}

	@Override
	public boolean pop() {
		if (isEmpty()) {
			System.out.println("[ERROR] Atempt to pop from a empty stack!");
			return false;
		} else {
			topOfStack = topOfStack.next;
			size--;
			return true;
		}
	}

	@Override
	public boolean push(Object x) {
		if (isFull()) {
			System.out.println("[ERROR] Atempt to push into a full stack!");
			return false;
		} else {
			ListNode temp = new ListNode(x);
			temp.next = topOfStack;
			topOfStack = temp;
			size++;
			return true;
		}
	}

	@Override
	public Object top() {
		if (isEmpty()) {
			System.out.println("[ERROR] Atempt to get the top element from a empty stack!");
			return null;
		}
		return topOfStack.element;
	}

}

3，节点类型

package pku.ss.datastructure.StackLi;

public class ListNode {
	ListNode(Object theElement) {
		this(theElement, null);
	}

	ListNode(Object theElement, ListNode aNext) {
		element = theElement;
		next = aNext;
	}
	
	Object element;  //节点中的元素
	ListNode next;   //指向下一个节点
}

4，测试类

package pku.ss.datastructure.Demo;

import pku.ss.datastructure.StackLi.StackLi;

public class StackLiDemo {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		StackLi stack = new StackLi(5);
		stack.push("A");
		stack.push("B");
		stack.push("C");
		stack.push("D");
		stack.push("E");
		stack.push("F");
		stack.push("G");
		stack.push("H");
		System.out.println("**********************");

		System.out.println("The size of the stack is: " + stack.getSize());

		System.out.println("**********************");
		System.out.println("The top element of the stack is: " + stack.top());

		System.out.println("**********************");
		stack.makeEmpty();
		System.out.println("The top element of the stack is: " + stack.top());

		System.out.println("**********************");

		System.out.println("The size of the stack is: " + stack.getSize());
	}

}