Automatically throwing IllegalArgumentException when empty values ​​are passed to the method

Question

I am exploring the possibility of eliminating null, as well as refactoring the part of the code base that I'm working on. We upgraded to java 8, so we have it Optional<T>. To do this efficiently, we need to make sure that null is not passed to any of our methods (this is after we complete any potential NULL values ​​inside Optionalthat enter our system from external services / libraries). The obvious way to handle this is to explicitly check the null value and drop IllegalArgumentExceptionit if necessary, however this would be unreasonably verbose and manual. Is there a less manual / easier way to do this?

Answer 1

You can use Objects::requireNonNullfor this. For example, in the constructor, you can:

this.myField = Objects.requireNonNull(myField);

He will send NullPointerExceptionif you pass null.

Avoid overuse Optional. See for example this answer .

Answer 2

You can try the Lombok comment handler, which has an @NonNull annotation. Annotating a parameter using NonNull will automatically generate a zero check at compile time, so you will get either NullPointerException, or IllegalArgumentException(depending on what you like) at runtime.

Answer 3

, @Nonnull ( ) , Guava:

import javax.annotation.Nonnull;
import static com.google.common.base.Preconditions.checkNotNull;

public void doSomething(@Nonnull MyClass input) {
    checkNotNull(input);
    /* Do something */
}

@Nonnull IDE , FindBugs, , . checkNotNull , NullPointerException, - null .

Answer 4

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java :

assert n != null;

, throw, AssertionError, . , , , , , , IllegalArgumentException, :

assert n != null : new IllegalArgumentException( "n cannot be null" );

, n - null, AssertionError, IllegalArgumentException. , IllegalArgumentException , "Caused by:".

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Answer 5

Checker @NonNull, , , .

See: https://checkerframework.org/api/org/checkerframework/checker/nullness/qual/NonNull.html