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When is handling a null pointer/reference exception preferred over doing a null check?

由 心已入冬 提交于 2020-01-24 12:42:45
问题 I have an odd question that I have always thought about, but could never see a practical use for. I'm looking to see if there would be enough justification for this. When is handling a null pointer/reference exception preferred over doing a null check? If at all. This applies to any language that has to deal with null pointers/references which has exception handling features. My usual response to this would be to perform a null check before doing anything with the pointer/reference. If non

When is handling a null pointer/reference exception preferred over doing a null check?

由 和自甴很熟 提交于 2020-01-24 12:42:26
问题 I have an odd question that I have always thought about, but could never see a practical use for. I'm looking to see if there would be enough justification for this. When is handling a null pointer/reference exception preferred over doing a null check? If at all. This applies to any language that has to deal with null pointers/references which has exception handling features. My usual response to this would be to perform a null check before doing anything with the pointer/reference. If non

When is handling a null pointer/reference exception preferred over doing a null check?

由 此生再无相见时 提交于 2020-01-24 12:42:14
问题 I have an odd question that I have always thought about, but could never see a practical use for. I'm looking to see if there would be enough justification for this. When is handling a null pointer/reference exception preferred over doing a null check? If at all. This applies to any language that has to deal with null pointers/references which has exception handling features. My usual response to this would be to perform a null check before doing anything with the pointer/reference. If non

Why nullable types will not be equal in this case?

由 别说谁变了你拦得住时间么 提交于 2020-01-24 12:13:24
问题 Surprisingly the code bellow will not succeed. int? n1 = null; int? n2 = null; Assert.IsTrue(n1 <= n2); // Fails here Do you know why? 回答1: Using boolean logic with null nullable values in C# (and VB.Net) often times defies logic. I find the best way to make sense of it is to remember that "null is not a value". Because null is not a value you cannot do any operations on it. Hence things like " 1 > null " and " 1 < null " are both true. Here is a detailed guide: http://msdn.microsoft.com/en

How can I annotate my helper method so Eclipse knows its argument is non null if it returns true?

由 流过昼夜 提交于 2020-01-24 05:41:05
问题 I have a helper method, hasContent(String) , which returns true iff its argument is both non-null and contains at least one non-whitespace character. I have just enabled null analysis in Eclipse and I have found that when I use this method to execute a block of code which is conditional on the result of my helper function indicating that the string has content (and therefore cannot be null), that nonetheless Eclipse complains that my String might still be null. The helper function public

Is it possible to check for null inline in javascript?

由 会有一股神秘感。 提交于 2020-01-24 02:16:26
问题 I have a function which parses the address components of the Google Maps API JSON and then returns the city / locality / route name. The getAddressComponent() returns a null if it cannot find the key. let route = getAddressComponent(addressComponents, 'route').value.long_name; So let's say it didn't find the key, then I get a Error: TypeError: Cannot read property 'long_name' of undefined obviously because it's not defined. How do I check for null in javascript other than the conditional

go语言中 json转换--nil

由 淺唱寂寞╮ 提交于 2020-01-24 00:59:43
go语言中如果一个变量的值为nil，是否能否为json？ 如果能否转换，转换后的结果是什么？ 下面直接看下例子。 package main import ( "encoding/json" "fmt" ) func main() { marshalTest() } func marshalTest() { b, err := json.Marshal(nil) if err != nil { fmt.Println("json.Marshal failed:", err) return } fmt.Println("result:", string(b)) } output: result: null 结果输出为"null"。 也就是说，凡是值为nil的变量，经过json编码后都是"null"。例如，未赋值的指针变量、切片slice等： var ptr *int var s []int 反过来，如果一个json字符串是"null"，经过解析后，转换后的值是什么样呢? 例如，转换为结构体，转换后为结构体变量的默认值。 package main import ( "encoding/json" "fmt" ) func main() { unmarshalTest() } type Apple struct { Size int Addr string Num *int } func

Java 合并两个有序链表

由 久未见 提交于 2020-01-23 22:55:12
编程实现合并两个有序(假定为降序)单链表的函数，输入为两个有序链表的头结点，函数返回合并后新的链表的头节点， 要求：不能另外开辟新的内存存放合并的链表。 递归方式： /* * 递归方式 */ public LinkNode MergeLinkList(LinkNode head1,LinkNode head2){ if(head1 == null) return head2; if (head2 == null) return head1; LinkNode mergeHead = null; if(head1.value < head2.value){ mergeHead = head1; mergeHead.next = MergeLinkList(head1.next,head2); } else { mergeHead = head2; mergeHead.next = MergeLinkList(head1,head2.next); } return mergeHead; } 非递归方式： /* * 非递归方式 */ public LinkNode MergeLinkList_1(LinkNode head1,LinkNode head2){ if(head1 == null) return head2; if (head2 == null) return head1;

LeetCode不定时刷题——Merge Two Sorted Lists

由 [亡魂溺海] 提交于 2020-01-23 18:17:21
21. Merge Two Sorted Lists 递归 /** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode(int x) { val = x; } * } */ class Solution { public ListNode mergeTwoLists(ListNode l1, ListNode l2) { if(l1==null){ return l2; }else if(l2==null){ return l1; } if(l1.val < l2.val) { l1.next = mergeTwoLists(l1.next, l2); return l1; } else { l2.next = mergeTwoLists(l1, l2.next); return l2; } } } 非递归 /** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode(int x) { val = x; } * } */ class Solution { public ListNode

经典算法（三） 单链表 反转 & 是否相交/成环 & 求交点 等

由 徘徊边缘 提交于 2020-01-23 07:21:39
参考文章： 判断链表是否相交： http://treemanfm.iteye.com/blog/2044196 一、单链表反转 链表节点 public class Node { private int record; private Node nextNode; public Node(int record) { super(); this.record = record; } } View Code 构建链表 public static Node creatLinkedList() { Node head = new Node(0); Node tmp = null; Node cur = null; for (int i = 1; i < 10; i++) { tmp = new Node(i); if (1 == i) { head.setNextNode(tmp); } else { cur.setNextNode(tmp); } cur = tmp; } return head; } View Code 递归实现 public static Node reverse(Node head) { if (null == head || null == head.getNextNode()) { return head; } Node reversedHead =
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