How to check if a subclass is an instance of a class at runtime

Question

In an android app test suite I have a class like this where B is a view   public class A extends B       etc        now I have a list of view objects which may contain A objects but in this case I only care if they re subclasses or  instances of  B  I d like to do something like   ArrayList lt View gt  viewList   getViews    Iterator lt View gt  iterator   viewList iterator    while  iterator hasNext    amp  amp  viewList    null        View view   iterator next        if  view getClass   isInstance B class                this is an instance of B           The problem is that when the if encounters an A object it doesn t evaluate to an  instance of B   Is there a way to do isSubclassOf or something

User · Answer

If there is polymorphism such as checking SQLRecoverableException vs SQLException, it can be done like that.

try {
    // sth may throw exception
    ....
} catch (Exception e) {
    if(SQLException.class.isAssignableFrom(e.getCause().getClass()))
    {
        // do sth
        System.out.println("SQLException occurs!");
    }
}

Simply say,

ChildClass child= new ChildClass();
if(ParentClass.class.isAssignableFrom(child.getClass()))
{
    // do sth
    ...
}

User · Answer

if view instanceof B    This will return true if view is an instance of B or the subclass A  or any subclass of B for that matter

User · Answer

Maybe I m missing something  but wouldn t this suffice   if  view instanceof B           this view is an instance of B

User · Answer

I ve never actually used this  but try view getClass   getGenericSuperclass

User · Answer

It s the other way around  B class isInstance view

User · Answer

Class isAssignableFrom   - works for interfaces as well  If you don t want that  you ll have to call getSuperclass   and test until you reach Object

User · Answer

You have to read the API carefully for this methods  Sometimes you can get confused very easily   It is either   if  B class isInstance view     API says  Determines if the specified Object  the parameter  is assignment-compatible with the object represented by this Class  The class object you are calling the method at   or   if  B class isAssignableFrom view getClass       API says  Determines if the class or interface represented by this Class object is either the same as  or is a superclass or superinterface of  the class or interface represented by the specified Class parameter  or  without reflection and the recommended one    if  view instanceof B

[java] How to check if a subclass is an instance of a class at runtime?

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