Jul 22, 2019 · What is the 'instanceof' operator used for? I learned that Java has the instanceof operator. Can you elaborate where it is used and what are its advantages?

The java instanceof operator is used to test whether the object is an instance of the specified type (class or subclass or interface). The instanceof in java is also known as type comparison operator as it …

Jun 1, 2010 · No, a null check is not needed before using instanceof. The expression x instanceof SomeClass is false if x is null. The Java 11 Language Specification expresses this concisely in …

If class B and class C extend class A and I have an object of type B or C, how can I determine of which type it is an instance?

Oct 15, 2009 · Cannot perform instanceof check against type parameter E. Use instead its erasure Object since generic type information will be erased at runtime What is the better way to do it?

Nov 21, 2012 · 70 instanceof can be used to test if an object is a direct or descended instance of a given class. instanceof can also be used with interfaces even though interfaces can't be instantiated like …

Sep 13, 2012 · Is it possible in JUnit to assert an object is an instance of a class? For various reasons I have an object in my test that I want to check the type of. Is it a type of Object1 or a type of Object2?

This has different behaviour. The instanceof keyword includes subclasses, the method does not, you need to use Class.isAssignableFrom to replicate the behaviour.

Don't use isAssignableFrom. The correct way to write o instanceof String using reflection is String.getClass().isInstance(o). The javadoc even says so: This method is the dynamic equivalent of …

Apr 11, 2012 · For example - I have a local variable value which returns Object, and I need to check - if it's a list, if it is, check if the list type instanceof my interface.