What is a NullPointerException give an example?

NullPointerException is a runtime exception and it is thrown when the application try to use an object reference which has a null value. For example, using a method on a null reference.

What is the meaning of NullPointerException?

Class NullPointerException These include: Calling the instance method of a null object. Accessing or modifying the field of a null object. Taking the length of null as if it were an array. Accessing or modifying the slots of null as if it were an array.

What is a NullPointerException and how do I fix it?

NullPointerException is thrown when a reference variable is accessed (or de-referenced) and is not pointing to any object. This error can be resolved by using a try-catch block or an if-else condition to check if a reference variable is null before dereferencing it.

How do I stop NullPointerException in equals method?

Answer: Some of the best practices to avoid NullPointerException are:

1. Use equals() and equalsIgnoreCase() method with String literal instead of using it on the unknown object that can be null.
2. Use valueOf() instead of toString() ; and both return the same result.
3. Use Java annotation @NotNull and @Nullable.

Can we catch null pointer exception?

As stated already within another answer it is not recommended to catch a NullPointerException. However you definitely could catch it, like the following example shows. Although a NPE can be caught you definitely shouldn’t do that but fix the initial issue, which is the Check_Circular method.

How can we avoid null pointer exception in Java with example?

Is NullPointerException a vulnerability?

The Denial-of-Service (DoS) attack due to Null Pointer Dereferencing vulnerability (CVE-2019-14604) can lead to vital exploits in the cloud scenario. A NULL pointer dereference exception occurs when an application dereferences an object that is expected to be valid but is NULL.