java中Stack的问题

java中Stack的问题

闲着实在无聊......

写了个简单的双链表实现Stack。未引用任何包。

public class Main {
public static void main(String[] args) {
Stack s = new Stack()
s.put("abc")//压栈
s.put("def")//压栈
s.put("ghi")
System.out.println(s.pop())//出栈
System.out.println(s.isEmpty())//判断栈是否为空
System.out.println(s.pop())
System.out.println(s.isEmpty())
System.out.println(s.pop())
System.out.println(s.isEmpty())
}
}

class Stack {

private Node root = new Node()
private Node top = root

public Object pop() {
if(top != null) {
Object value = top.getValue()
top = top.getPrevious()
return value
} else {
return null
}
}

public void put(Object value) {
Node n = new Node(top, value)
top.setNext(n)
top = n
}

public boolean isEmpty() {
return top.getPrevious() == null
}

}

class Node {
private Node next
private Object value
private Node previous

public Node() {

}

public Node(Node previous, Object value) {
this.previous = previous
this.value = value
}

public Node getNext() {
return next
}

public void setNext(Node next) {
this.next = next
}

public Object getValue() {
return value
}

public void setValue(Object value) {
this.value = value
}

public Node getPrevious() {
return previous
}

public void setPrevious(Node previous) {
this.previous = previous
}

}