![]() How to fix the errorĬreating a null pointer exception is easy, but avoiding or fixing it is tricky. Due to the thrown exception, the JVM cannot execute any instructions after this. This is where a NullPointerException is thrown. When the sb.append () lines are executed, sb does not point to any object, it points to null. Let’s look at the modified version which will throw a null pointer exception:Īs you can see, we haven’t initialized an instance of the StringBuilder class as we stated. If you run the above snippet, it will work fine. ![]() Here’s how the class would normally be used to create strings: StringBuilder is a class used to handle the formation and manipulation of strings. For example, consider the StringBuilder class. įinding examples of is not a difficult task, as all you need to do is not initialize a variable before trying to access it. This happens because there is no data actually stored in the variable points to an empty entity. If you try to perform certain operations on the data stored in a zero-pointing variable, the system will not know what to do. ![]() The problem with a zero pointing variable is that the variable is only a reference and does not point to anything. This shows that since the variable str is not initialized, it currently points to, or holds the value, null. Consider the following example where you declare a variable like this:Īnd then try to print the contents of the variable:Īs you can see above, ’null’ is printed on the output. Null is the default value in Java assigned to variables that are not initialized by the user after or with an instruction. This indicates that an attempt was made to access a reference variable that currently points to null. The Null Pointer exception is one of the many exceptions supported by the Java language. In this article, let’s take a look at what is, why it occurs, how you can fix it, and some of the best practices to avoid hitting wild null pointers. This problem is not entirely a syntax error, so it can sometimes be difficult to identify it. This exception is usually the result of human error, but time can be wasted debugging errors like this. One of the most common errors in developing Java applications is the null pointer exception. You must have encountered something called NullPointerException if you have worked on Java based applications. □ Check our latest review to choose the best laptop for Machine Learning engineers and Deep learning tasks!
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