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Will null instanceof SomeClass return false or throw a NullPointerException?
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Using the instanceof Operator When an Object Is nullIf we use the instanceof operator on any object that's null, it returns false. We also don't need a null check when using an instanceof operator.
In any case, it is always good practice to CHECK for nulls on ANY parameters passed in before you attempt to operate on them, so you don't get NullPointerExceptions when someone passes you bad data. Show activity on this post. If you don't know whether you should do it, the chances are, you don't need to do it.
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 section 15.20. 2, "Type comparison operator instanceof".
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 section 15.20.2, "Type comparison operator instanceof". (Java 17 expresses this less concisely, after the introduction of instanceof patternmatching.)
"At run time, the result of the
instanceofoperator istrueif the value of the RelationalExpression is notnulland the reference could be cast to the ReferenceType without raising aClassCastException. Otherwise the result isfalse."
So if the operand is null, the result is false.
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