Inner Classes

Q1: Which is true about an anonymous inner class?

A It can extend exactly one class and implement exactly one interface.

B It can extend exactly one class and can implement multiple interfaces.

C It can extend exactly one class or implement exactly one interface.

D It can implement multiple interfaces regardless of whether it also extends a class.

Q2:
class Boo 
{
    Boo(String s) { }
    Boo() { }
}
class Bar extends Boo 
{
    Bar() { }
    Bar(String s) {super(s);}
    void zoo() 
    {
    // insert code here
    }
}
which one create an anonymous inner class from within class Bar?

A Boo f = new Boo(24) { };

B Boo f = new Bar() { };

C Bar f = new Boo(String s) { };

D Boo f = new Boo.Bar(String s) { };

Q3: Which statement is true about a static nested class?

A You must have a reference to an instance of the enclosing class in order to instantiate it.

B It does not have access to nonstatic members of the enclosing class.

C It's variables and methods must be static.

D It must extend the enclosing class.

Q4: Which is true about a method-local inner class?

A It must be marked final.

B It can be marked abstract.

C It can be marked public.

D It can be marked static.

Q5: Which constructs an anonymous inner class instance?

A Runnable r = new Runnable() { };

B Runnable r = new Runnable(public void run() { });

C Runnable r = new Runnable { public void run(){}};

D System.out.println(new Runnable() {public void run() { }});

Q6:
public class MyOuter 
{
    public static class MyInner 
    {
        public static void foo() { }
    }
}
which statement, if placed in a class other than MyOuter or MyInner, instantiates an instance of the nested class?

A MyOuter.MyInner m = new MyOuter.MyInner();

B MyOuter.MyInner mi = new MyInner();

C MyOuter m = new MyOuter(); MyOuter.MyInner mi = m.new MyOuter.MyInner();

D MyInner mi = new MyOuter.MyInner();

Q7:
class Foo 
{
    class Bar{ }
}
class Test 
{
    public static void main (String [] args) 
    {
        Foo f = new Foo();
        /* Line 10: Missing statement ? */
    }
}
which statement, inserted at line 10, creates an instance of Bar?

A Foo.Bar b = new Foo.Bar();

B Foo.Bar b = f.new Bar();

C Bar b = new f.Bar();

D Bar b = f.new Bar();

Q8: Which is true about a method-local inner class?

A It must be marked final.

B It can be marked abstract.

C It can be marked public.

D It can be marked static.


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