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Java解决No enclosing instance of type PrintListFromTailToHead is accessible问题的两种方案

2016-07-24 15:35 801 查看

今天在编译Java程序时遇到如下问题:

No enclosing instance of type PrintListFromTailToHead is accessible. Must qualify the allocation with an enclosing instance
of type PrintListFromTailToHead (e.g. x.new A() where x is an instance of PrintListFromTailToHead).

源代码为:

public class PrintListFromTailToHead {
public static void main(String[] args) {
ListNode one = new ListNode(1);
ListNode two = new ListNode(2);
ListNode three = new ListNode(3);
one.next = two;
two.next = three;
ArrayList<Integer> result = printListFromTailToHead(one);
System.out.println("结果是:" + result);
}
class ListNode {
public int val;
public ListNode next;
public ListNode() {
}
public ListNode(int val) {
this.val = val;
}
}
public static ArrayList<Integer> printListFromTailToHead(ListNode listNode) {
Stack<Integer> stack = new Stack<Integer>();
while (listNode != null) {
stack.push(listNode.val);
listNode = listNode.next;
}
ArrayList<Integer> arrayList = new ArrayList<Integer>();
while (!stack.isEmpty()) {
arrayList.add(stack.pop());
}
return arrayList;
}
}

问题解释:

代码中,我的ListNode类是定义在PrintListFromTailToHead类中的内部类。ListNode内部类是动态的内部类,而我的main方法是static静态的。

就好比静态的方法不能调用动态的方法一样。

有两种解决办法:

第一种:

将内部类ListNode定义成静态static的类。

第二种:

将内部类ListNode在PrintListFromTailToHead类外边定义。

两种解决方法:

第一种:

public class PrintListFromTailToHead {
public static void main(String[] args) {
ListNode one = new ListNode(1);
ListNode two = new ListNode(2);
ListNode three = new ListNode(3);
one.next = two;
two.next = three;
ArrayList<Integer> result = printListFromTailToHead(one);
System.out.println("结果是:" + result);
}
static class ListNode {
public int val;
public ListNode next;
public ListNode() {
}
public ListNode(int val) {
this.val = val;
}
}

第二种:

public class PrintListFromTailToHead {
public static void main(String[] args) {
ListNode one = new ListNode(1);
ListNode two = new ListNode(2);
ListNode three = new ListNode(3);
one.next = two;
two.next = three;
}
public static ArrayList<Integer> printListFromTailToHead(ListNode listNode) {
Stack<Integer> stack = new Stack<Integer>();
while (listNode != null) {
stack.push(listNode.val);
listNode = listNode.next;
}
ArrayList<Integer> arrayList = new ArrayList<Integer>();
while (!stack.isEmpty()) {
arrayList.add(stack.pop());
}
return arrayList;
}
}
class ListNode {
public int val;
public ListNode next;
public ListNode() {
}
public ListNode(int val) {
this.val = val;
}
}

以上所述是小编给大家介绍的Java解决No enclosing instance of type PrintListFromTailToHead is accessible问题的两种方案,希望对大家有所帮助。

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