When to throw nullpointerexception back at the caller?

If the caller passes null, but null is not a valid argument for the method, then it's correct to throw the exception back at the caller because it's the caller's fault. Silently ignoring invalid input and doing nothing in the method is extremely poor advice because it hides the problem.
Additionally, when is it appropriate to throw a NullPointerException?
If the method is intended to do something to the passed-in object as the above method does, it is appropriate to throw the NullPointerException because it's a programmer error and the programmer will need that information for debugging purposes.
Next, what is a null pointer exception in Java? NullPointerExceptions are exceptions that occur when you try to use a reference that points to no location in memory (null) as though it were referencing an object. Calling a method on a null reference or trying to access a field of a null reference will trigger a NullPointerException.
Accordingly, why do I get a NullPointerException when I try to dereference NUM?
If you attempt to dereference num before creating the object you get a NullPointerException. In the most trivial cases, the compiler will catch the problem and let you know that " num may not have been initialized ," but sometimes you may write code that does not directly create the object.
Subsequently, why do I get a NullPointerException when I declare a variable?
The Exception that you asked about occurs when you declare a variable but did not create an object. If you attempt to dereference num BEFORE creating the object you get a NullPointerException.

20 Similar Question Found

Why does java.util.collections throw a nullpointerexception?

It contains polymorphic algorithms that operate on collections, "wrappers", which return a new collection backed by a specified collection. The methods of this class all throw a NullPointerException if the collections or class objects provided to them are null. Following is the declaration for java.util.Collections class −

When does findfirst throw nullpointerexception in java?

If the selected element by findFirst is null, it throws NullPointerException . The findFirst method returns Optional containing first element in the stream. The findFirst throws NullPointerException if selects null value. The findFirst is a short-circuiting terminal operation.

When to throw nullpointerexception in java stream?

The method argument shall be a non-interfering, stateless Comparator. The method returns an Optional describing the smallest element of this stream, or an empty Optional if the stream is empty. It may throw NullPointerException if the smallest element is null. 2. Java Stream min () Example

When to throw a nullpointerexception in webtarget?

NullPointerException - if path is null. Create a new WebTarget instance by resolving a URI template with a given name in the URI of the current target instance using a supplied value. In case a null template name or value is entered a NullPointerException is thrown.

When to throw a nullpointerexception in java?

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. Taking the length of null as if it were an array.

Why does getcontext ( ) throw a nullpointerexception?

instance is never initialized and so has a default value of null. This means that instance.getContext () will throw a NullPointerException. To fix this, you need to initialize the instance variable. Currently, you have not initialized instance and by default it's value would now be set to null. You need to assign it a value before you can use it.

When to throw nullpointerexception in java orelseget?

Exception: This method throws NullPointerException if there is no value present in this Optional instance. import java.util.function.*; import java.util.function.*;

Why does switch ( i ) throw a nullpointerexception?

switch (i) will throw a NullPointerException if i is null, because it will try to unbox the Integer into an int. So case null, which happens to be illegal, would never have been reached anyway. You need to check that i is not null before the switch statement.

When do you throw a nullpointerexception in java?

NullPointerException is a RuntimeException. In Java, a special null value can be assigned to an object reference. NullPointerException is thrown when program attempts to use an object reference that has the null value. Invoking a method from a null object. Accessing or modifying a null object’s field.

When to use optional to avoid nullpointerexception?

You can use Optional to encapsulate the potential null values and pass or return it safely without worrying about the exception. Without Optional, when a method signature has return type of certain object. The user often tend to assert the existence of the object. Hence, the possibility of null is often ignored.

When do you get a nullpointerexception in java?

According to the Javadoc for NullPointerException, it's thrown when an application attempts to use null in a case where an object is required, such as: Calling an instance method of a null object Accessing or modifying a field of a null object Taking the length of null as if it were an array

What does nullpointerexception do in java keymanagerfactory?

NullPointerException - if algorithm is null. Returns a KeyManagerFactory object that acts as a factory for key managers. A new KeyManagerFactory object encapsulating the KeyManagerFactorySpi implementation from the specified provider is returned. The specified provider must be registered in the security provider list.

When to use nullpointerexception in trust manager?

NoSuchAlgorithmException - if no Provider supports a TrustManagerFactorySpi implementation for the specified algorithm. NullPointerException - if algorithm is null. Returns a TrustManagerFactory object that acts as a factory for trust managers.

Why do i get nullpointerexception while pasting in bukkit?

While pasting, i keep getting a NullPointerException in the pasting process. When i logged what items were getting placed, i see grass blocks, stone, but not my chests, anything in the chests, or beacons (Maybe even more blocks).

What's the difference between isnullorempty and nullpointerexception?

Yes , the only difference is NullPointerException. In isNullOrEmpty first it will check string is null or not .if it is not null then it will check it is check string is empty or not . If any of the condition will true then method will return true.

When do you get a nullpointerexception in sslcontext?

NoSuchAlgorithmException - if no Provider supports a SSLContextSpi implementation for the specified protocol. NullPointerException - if protocol is null. Returns a SSLContext object that implements the specified secure socket protocol.

What does java.lang.nullpointerexception mean?

The java.lang.NullPointerException is an error in Java that occurs as a Java program attempts to use a null when an object is required. The NullPointerException is a public class that extends the RuntimeException. The NullPointerException is thrown for different scenarios, for example, if you call the instance method of an object which is null.

What does the nullpointerexception do in java?

NullPointerException in Java is a runtime exception. Java assigns a special null value to an object reference. When a program tries to use an object reference set to the null value, then this exception is thrown.

Is the nullpointerexception a checked or unchecked exception?

Answer: NullPointerException is not a checked exception. It is a descendant of RuntimeException and is unchecked. #3) How do I stop NullPointerException? Answer: Some of the best practices to avoid NullPointerException are: Use equals () and equalsIgnoreCase () method with String literal instead of using it on the unknown object that can be null.

Why did i get a nullpointerexception in mockito?

But definitely, NullPointerException happened because you want something which is not there. Check if you are returning something. 2. Specify Mockito running class