Java instanceof with changing objects

Use Class.isInstance(Object).

How about this:

public boolean checker(Object obj) {
    return obj instanceof SomeClass;
}

or if SomeClass needs to be a parameter:

public boolean checker(Object obj, Class someClass) {
    return someClass.isInstance(obj);
}

or if you want the instance to be someClass and NOT an instance of a subclass of someClass:

public boolean checker(Object obj, Class someClass) {
    return someClass.equals(obj.getClass());
}

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