Java数据结构之栈

1.结点类

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   
}  

2.栈的接口

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();   
       
} 

 

3.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;   
    }   
  
}  

 4.测试

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());   
    }   
  
}