Java

Using Duration.withNanos() may produce wrong results, because it will only set the value of the nanoseconds field of the duration, and will not correctly adjust for any overflow.

The Java analyzer has detected a narrowing cast of a subtraction in a comparison method that may flip the sign of the result.

If a method of a superclass has one particular nullability annotation applied to it, avoid marking any overrides in subtypes with a different nullability annotation.

Make sure to use the same annotation present on the super method as much as possible.

This class inherits from JUnit's TestCase class and implements the setUp() method. The setUp method should call super.setUp(), but doesn't.

The super method is annotated with @OverridingMethodsMustInvokeSuper, but the overriding method isn't calling the super method.

A call has been made to an unsupported method.

close() is being invoked on a value that is always null. If this statement is executed, a null pointer exception will occur. Another serious issue is the fact that the resource that is meant to be closed is not closed.

This loop doesn't seem to have a way to terminate (other than by perhaps throwing an exception).

It is better to explicitly break out of the loop instead of relying on a possibly unclear exit condition.

BigDecimals constructed from a double may not be represented correctly.

This class extends from a Servlet class, and uses an instance member variable. Since only one instance of a Servlet class is created by the J2EE framework, and it is used in a multithreaded way, this paradigm is highly discouraged and most likely problematic. Consider only using method local variables, or implement proper synchronization on the static fields.

readResolve() must return only java.lang.Object, not any other type.

The serialVersionUID field must be declared as <access modifier> static final long serialVersionUID. Not declaring it as such will prevent Java from processing it.

A double assignment of a variable to itself has been detected. This may be a typo.

Check whether this is correct and edit it or remove the extra assignment.

Deprecated methods from java.lang.Thread such as Thread.stop() or Thread.suspend() should not be used as they can cause instability.

Always terminate calls to assertThat() or verify() with a relevant assertion call, such as equals(), or similar.

A method with a Boolean return type returns an explicit null. This is likely intentional, but be aware that API consumers may not realize that.

This code is casting the result of calling toArray() on a collection to a subtype of Object[], as in:

Throwing null is a bad practice and should be avoided, as it serves no meaningful purpose.