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Questions tagged [null-check]

A check to see that an object has been instantiated.

A check to see that an object has been instantiated.

Typically, in a OO programming language, this is to see whether an object has been created or not.

e.g (Java example)

public void doStuff(Object obj) {
    if (obj != null) {
        // Do stuff with the object
    }
}
217 questions
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1 linear, beauty and clean way to assign value if null in C#?

Before you rush to think about the ?? null coalescing operator: string result = myParent.objProperty.strProperty ?? "default string value if strObjProperty is null"; The problem here is when whether myParent or objProperty are null, then it will…
renzol
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How to write a generic isEmpty method which can check for null, empty?

I am writing a utility method which can check for empty and null string, or collection or an object or any general types - public static boolean isEmpty(Object obj) { if (obj == null) return true; if (obj instanceof Collection) …
john
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Why does String.Equals(Object obj) check to see if this == null?

Possible Duplicate: Why check this != null? // Determines whether two strings match. [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)] public override bool Equals(Object obj) { //this is necessary to guard against…
myermian
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Check if Array element is not null in one line C#

I got a neighbor array (consisting of Tile objects), that always has the length of 4, regardless if all elements are filled or not. I want to scan through that array and change the color of a PB contained in the Tile if that element / position is…
Sander Koldenhof
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C# Repetitive code with null check

I'm working with RPC(protobuf-remote) and I need to do some checking in case the other end(server) is down. Let's say I've lot's of RPC methods, like: public FirstObj First(string one, string two) { if (rpc == null) return…
user6168313
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5 answers

Struts2, String null check

I'm trying to do a null check on a String but it won't work. 0 …
user425367
5
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1 answer

Null analysis in eclipse compatibility break between 7 and 8

I have encountered strange behaviour of nullcheck analysis under Spring tool suite 3.6.2 (Eclipse clon) on windows 7 64bit with Oracle java 8u25. The same maven project with java 7 source compatibility successfully finds NPE error in eclipse, but…
kulatamicuda
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Efficient null check in Java 11

I need to use a getter which is 3 levels down in the object. response.getServiceError().getErrorCode() It is possible one or more objects could be NULL. Now, I am doing this if (response != null && response.getServiceError() != null &&…
Trozan
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Java 8 requireNonNull method with supplier parameter performance

Method Objects.requireNonNull with Supplier added in Java 8, but I'm not sure what's the performance improvement declared: While this may confer a performance advantage in the non-null case, when deciding to call this method care should be taken…
Ori Marko
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kotlin inverse boolean safe casting

Let's say I have an object Response. Now I would like to check a boolean variable, success, under Response and do an early return is response is not successful. if(response == null || !response.success){ return; } //Java version Now I would…
Yao
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Does C# JIT compiler optimize null-check?

There are many articles online that list the optimizations made by the C# JIT before executing a piece of code. For example this post on MSDN talks about: Constant folding, Constant and copy propagation, Common subexpression elimination, Code…
Massimiliano Kraus
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Java 8 avoiding null pointer checks using Optional

Is it possible to write something like this and to avoid checking if elements are not null and collections not empty: response.getBody() .getRequestInformation() .getRequestParameters().get(0) .getProductInstances().get(0) …
Aleksandar
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how to do null \ nil check in LUA with redis-scripto and redis DB?

I'm writing a script in node.js, using scripto, and I'm trying to do a nil check to a value from the database: here is the js code (for node)- var redis = require("redis"); var redisClient = redis.createClient("6379","localhost"); var Scripto =…
Aviram Netanel
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Java string null check by != null or !str.equals(null)?

What's the best way to check for not null values in java. String query ="abcd"; query != null vs !query.equals(null). which is better?why?
yonikawa
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How to disable "unnecessary test for null" warning in NetBeans 14?

Short Version How do i disable the "unnecessary test for null" warning in NetBeans 14 IDE? Long Version NetBeans as a well-known bug 1 2 3 4 where it will erroneously tell you that a test for null is unnecessary. For example in the following…
Ian Boyd
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