Java棧實現

1. 定義棧全部方法接口：
package com.dataStructure.stack;

/**
 * 類功能描述:
 *
 * @version 1.0.0
 * @auther Create by Barry
 * @date Create on 2018/3/12.
 * @history
 */
public interface Stack {
    public boolean push(Object element);

    public Object pop();

    public Object peek();

    public int elementCount();

    public boolean isEmpty();

    public void showElements();
}

2. 基於數組的棧實現

package com.dataStructure.stack;

/**
 * 類功能描述:
 *
 * @version 1.0.0
 * @auther Create by Barry
 * @date Create on 2018/3/12.
 * @history
 */
public class ArrayStack implements Stack{
    private int maxSize;
    private Object data[];
    private int top = -1;

    public ArrayStack(int maxSize){
        data = new Object[maxSize];
        this.maxSize = maxSize;
    }

    @Override
    public boolean push(Object element){
        if(top == maxSize-1){
            return false;
        }
        data[++top] = element;
        return true;
    }

    @Override
    public Object pop(){
        if(this.isEmpty()){
            return -1;
        }
        Object returnData = data[top];
        top--;
        return returnData;
    }

    @Override
    public Object peek(){
        if(this.isEmpty()){
            return -1;
        }
        return data[top];
    }

    @Override
    public int elementCount(){
        return top+1;
    }

    @Override
    public boolean isEmpty(){
        if(top == -1){
            return true;
        }
        return false;
    }

    @Override
    public void showElements(){
        System.out.println("--------Show all element start--------");
        for(int i=top; i>=0; i--){
            System.out.println(data[i]);
        }
        System.out.println("--------Show all element end--------");
    }

    public static void main(String[] args){
        Stack stack = new ArrayStack(11);

        /*System.out.println("=============================test 1 start--------------");
        stack.push(1);
        stack.showElements();
        System.out.println(stack.elementCount());
        System.out.println("=============================test 1 end--------------");
        System.out.println("=============================test 2 start--------------");
        stack.push(2);
        stack.showElements();
        System.out.println(stack.elementCount());
        System.out.println("=============================test 2 end--------------");
        System.out.println("=============================test 3 start--------------");
        stack.pop();
        stack.showElements();
        System.out.println(stack.elementCount());
        System.out.println("=============================test 3 end--------------");*/
        /*System.out.println("=============================test 4 start--------------");
        for(int i=1; i<=12; i++ ){
            stack.push(i);
        }
        stack.showElements();
        System.out.println(stack.elementCount());
        System.out.println("=============================test 4 end--------------");*/

        String str = "1234321";
        System.out.println(ArrayStack.isSysmetryStr(str));
    }

    /**
     * 用棧判斷字符串是否爲對稱串，
     * 即從左到右和從右到左讀取是同樣的
     * 1234321爲對稱串
     * @param str
     * @return
     */
    public static boolean isSysmetryStr(String str){
        if(str == null || str.length() == 0){
            return true;
        }

        Stack stack = new ArrayStack(str.length());
        for(int i=0; i < str.length(); i++){
            stack.push((int)str.charAt(i));
        }

        for(int i=0; i < str.length(); i++){
            Object data = stack.pop();
            if((int)data == (int)str.charAt(i)){
                return false;
            }
        }

        return true;
    }
}

3. 基於鏈表的棧實現

package com.dataStructure.stack;/** * 類功能描述: * * @version 1.0.0 * @auther Create by Barry * @date Create on 2018/3/12. * @history */public class LinkedStack implements Stack{    private Node header;    private int elementCount = 0;    private int maxSize;    public LinkedStack(int maxSize){        this.maxSize = maxSize;    }    @Override    public boolean push(Object data) {        if(elementCount == maxSize){            throw new RuntimeException("Stack is Full");        }        header = new Node(data, header);        elementCount++;        return true;    }    @Override    public Object pop() {        if(isEmpty()){            throw new RuntimeException("Stack is empty");        }        Object returnData = header.data;        header = header.next;        elementCount--;        return returnData;    }    @Override    public Object peek() {        return header.data;    }    @Override    public int elementCount() {        return elementCount;    }    @Override    public boolean isEmpty() {        return (elementCount == 0);    }    @Override    public void showElements() {        while (header != null){            System.out.println(header.data);            header = header.next;        }    }    class Node{        private Object data;        private Node next;        public Node(Object data){            this(data, null);        }        public Node(Object data, Node next){            this.data = data;            this.next = next;        }    }    public static void main(String[] args) {        Stack stack = new ArrayStack(5);        for(int i=1; i<=5; i++){            stack.push(i);        }        stack.pop();        stack.showElements();    }}