Avoiding NullPointerException in Java

I use x != null to avoid NullPointerException. Is there an alternative?

if (x != null) {
    // ...
}

Comments

  1. MeconOctober 12, 2022 at 11:29 PM

    4


    Other than catching the error, if you are going to work with something which might be null, you might want to throw in null checks.

    What you could do to reduce the chances of having to make null checks, would be to never return null from your methods, unless it is really necessary, for instance:

    public IList getUserNames()
    {
    //No usernames found...
    return new ArrayList();

    //As opposed to returning null
    return null;
    }
    By returning the empty list, a call to the above code would result into something like so: for(String name : this.getUserNames()) {...}. If no user names where found, the loop will not execute.

    If on the other hand, you return null, you would need to do something like so:

    List userNames = this.getUsernames();
    if(userNames != null)
    for(String userName : userNames) {....}

    ReplyDelete

Post a Comment

Popular posts from this blog

How do I generate random integers within a specific range in Java?

Image
How do I generate a random  int  value in a specific range? The following methods have bugs related to integer overflow: randomNum = minimum + ( int )(Math.random() * maximum); // Bug: `randomNum` can be bigger than `maximum`. Random rn = new Random (); int n = maximum - minimum + 1 ; int i = rn.nextInt() % n; randomNum = minimum + i; // Bug: `randomNum` can be smaller than `minimum`. java random integer Share Improve this question Follow edited  Oct 4 at 10:08 Ramesh R 6,805 4 4 gold badges 24 24 silver badges 37 37 bronze badges asked  Dec 12, 2008 at 18:20 user42155 47.8k 27 27 gold badges 58 58 silver badges 60 60 bronze badges When you need a lot of random numbers, I do not recommend the Random class in the API. It has just a too small period. Try the  Mersenne twister  instead. There is  a Java implementation .   –  raupach   Dec 13, 2008 at 10:18   35 Before you post a new answer, consider there are already 65+ a...
Read more

#1 javascript toturial

Image
  JavaScript is the world's most popular programming language. JavaScript is the programming language of the Web. JavaScript is easy to learn. This tutorial will teach you JavaScript from basic to advanced. Start learning JavaScript now » Examples in Each Chapter With our "Try it Yourself" editor, you can edit the source code and view the result. Example My First JavaScript Click me to display Date and Time Try it Yourself » Use the Menu We recommend reading this tutorial, in the sequence listed in the menu. If you have a large screen, the menu will always be present on the left. If you have a small screen, open the menu by clicking the top menu sign  ☰ . Learn by Examples Examples are better than 1000 words. Examples are often easier to understand than text explanations. This tutorial supplements all explanations with clarifying "Try it Yourself" examples. If you try all the examples, you will learn a lot about JavaScript, in a very short time! JavaScript Examp...
Read more

Proper use cases for Android UserManager.isUserAGoat()?

Image
I was looking at the new APIs introduced in  Android 4.2 . While looking at the  UserManager  class I came across the following method: public boolean isUserAGoat () Used to determine whether the user making this call is subject to teleportations. Returns whether the user making this call is a goat. How and when should this be used? java android usermanager Share Improve this question Follow edited  Sep 7, 2018 at 8:21 Luca Kiebel 9,395 7 7 gold badges 30 30 silver badges 43 43 bronze badges asked  Nov 14, 2012 at 8:34 Ovidiu Latcu 71k 15 15 gold badges 74 74 silver badges 84 84 bronze badges 8 If can be used to avoid some Java warning, as an easter egg, and as a test to see who read the API. And it's a reference to an easter egg in Chrome. –  Dorian   Nov 14, 2012 at 20:53   16 This might be related to when  Google use goats   as a mower  in their  Mountain View Headquarters .   –  John Isaiah Carmona Nov 15, 2012...
Read more