How to fix java lang nullpointerexception

How do I stop NullPointerException?

To avoid the NullPointerException, we must ensure that all the objects are initialized properly, before you use them. When we declare a reference variable, we must verify that object is not null, before we request a method or a field from the objects.

What causes null pointer exception?

NullPointerException is thrown when an application attempts to use an object reference that has the null value. These include: Calling an instance method on the object referred by a null reference. … If the reference type is an array type, accessing or modifying the slots of a null reference.

Can we catch NullPointerException?

Catching NullPointerException may mask an underlying null dereference, degrade application performance, and result in code that is hard to understand and maintain. Likewise, catching RuntimeException , Exception , or Throwable may unintentionally trap other exception types and prevent them from being handled properly.

How do you handle null in Java?

10 Tips to Handle Null Effectively

  1. Don’t Overcomplicate Things. …
  2. Use Objects Methods as Stream Predicates. …
  3. Never Pass Null as an Argument. …
  4. Validate Public API Arguments. …
  5. Return Empty Collections Instead of Null. …
  6. Optional Ain’t for Fields. …
  7. Use Exceptions Over Nulls. …
  8. Test Your Code.

How do you handle null pointer exception in junit?

If your object’s reference equals to null , a NullPointerException will be thrown. Instead, consider using the static String. valueOf method, which does not throw any exceptions and prints “null” , in case the function’s argument equals to null .

Is NullPointerException checked or unchecked?

Java NullPointerException is an unchecked exception and extends RuntimeException . NullPointerException doesn’t force us to use catch block to handle it. This exception is very much like a nightmare for most of java developer community. They usually pop up when we least expect them.

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What is Java null pointer exception?

public class NullPointerException extends RuntimeException. Thrown when an application attempts to use null in a case where an object is required. These include: Calling the instance method of a null object. Accessing or modifying the field of a null object.

Can we throw null pointer exception in Java?

Null is the default value of the object type, you can also manually assign null to objects in a method. Object obj = null; But, you cannot use an object with null value or (a null value instead of an object) if you do so, a NullPointerException will be thrown.

Is not null in Java?

It checks it using a null check using != null and isEmpty() method of string. In plain terms, if a string isn’t a null and isEmpty() returns false , it’s not either null or empty. … For string with spaces, we use string method trim() to trim out all the leading and trailing whitespace characters.

Is null in Java?

In Java(tm), “null” is not a keyword, but a special literal of the null type. It can be cast to any reference type, but not to any primitive type such as int or boolean. The null literal doesn’t necessarily have value zero. And it is impossible to cast to the null type or declare a variable of this type.

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