栈的实现（数组）
一、思路
1.Stack
代码如下（示例）：
package Stack;
//用数组来模拟栈
public class Stack {
private int maxsize; //数组最大容量
private int top; //初始化栈顶 初始值为-1
private int[] Stackarray;
public Stack(int arraymaxsize) {
maxsize = arraymaxsize;
Stackarray = new int[maxsize];
top = -1;
}
public boolean isFull() {
return top == maxsize - 1;
}
public boolean isEmpty() {
return top == -1;
}
public void push(int num) {
if (isFull()) {
System.out.println("栈已满，无法压栈");
return;
}
top++;
Stackarray[top] = num;
}
public int pop() {
if (isEmpty()) {
throw new RuntimeException("栈空，没有数据");
}
int value = Stackarray[top];
top--;
return value;
}
public void list() {
if (isEmpty()) {
System.out.println("栈空");
return;
}
for (int i = top; i >= 0; i--) {
System.out.printf("Stack[%d]=%d\n", i, Stackarray[i]);
}
}
}
2.StackDemo
代码如下（示例）：
package Stack;
import java.util.Scanner;
public class StackDemo {
public static void main(String[] args) {
Stack stack = new Stack(4);
String key;
Scanner scanner = new Scanner(System.in);
boolean loop = true;
while (loop)
{
System.out.println("show:显示栈");
System.out.println("exit:退出程序");
System.out.println("push:压栈");
System.out.println("pop:出栈");
System.out.println("输入你想要的功能");
key = scanner.next();
switch (key) {
case "show":
stack.list();
break;
case "exit":
scanner.close();
loop = false;
break;
case "push":
System.out.println("请输入一个数据");
int i = scanner.nextInt();
stack.push(i);
break;
case "pop":
try {
int value = stack.pop();
System.out.printf("出栈的数据为%d\n", value);
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
default:
break;
}
}
System.out.println("程序退出");
}
}
栈的实现（单向链表）
一、思路
头插法
1.Node类
代码如下（示例）：
package Stack;
public class Node {
int num;
Node next;
public Node(int num){
this.num = num;
}
@Override
public String toString() {
return "Node{" +
"num=" + num +
'}';
}
}
2.LinkedStack类
代码如下（示例）：
package Stack;
//单链表实现栈 头插入法
public class LinkedStack {
int length;
Node head = new Node(0);
public LinkedStack() {
length = 0;
}
public boolean isEmpty() {
return length == 0;
}
public int getLength() {
return length;
}
//入栈
public void push(Node node) {
node.next = head.next;
head.next = node;
length++;
}
//出栈
public Node pop() {
if (isEmpty()) {
throw new RuntimeException("链表为空");
}
Node node = head.next;
head.next = head.next.next;
length--;
return node;
}
//遍历栈
public void list() {
if (isEmpty()) {
System.out.println("链表为空，无法遍历");
return;
}
Node cur = head;
for (int i = 0; i < length; i++) {
Node next = cur.next;
System.out.println(next);
cur = cur.next;
}
}
}
3.LinkedStackDemo
代码如下（示例）：
package Stack;
public class LinkedStackDemo {
public static void main(String[] args) {
LinkedStack linkedStack= new LinkedStack();
Node node1 = new Node(10);
Node node2 = new Node(20);
Node node3 = new Node(30);
Node node4 = new Node(40);
linkedStack.push(node1);
linkedStack.push(node2);
linkedStack.push(node3);
linkedStack.push(node4);
linkedStack.list();
System.out.println("=======");
Node pop = linkedStack.pop();
System.out.println(pop);
int length = linkedStack.getLength();
System.out.println(length);
linkedStack.list();
linkedStack.pop();
linkedStack.pop();
linkedStack.pop();
System.out.println("=");
linkedStack.list();
linkedStack.push(node1);
linkedStack.list();
}
}
总结
两种实现方法都可以。数组好理解，链表头插法也好理解。