What is controls and what are different types of controls in AWT? | Core Java

Controls are bassically a components, Which is allow a user to interact with your application.  AWT supports the following types of controls :

•  Labels,
•  Push Buttons,
•  Check Boxes,
•  Choice Lists,
•  Lists,
•  Scrollbars,
•  Text Components.

What is source and listener ? | Core Java

They are defined as :
> A source : It is an object that generates an event. This occurs when the internal state of that object changes in some way.
> A listener : It is an object that is notified when an event occurs. It has two major requirements.
    * It must have been registered with a source to receive notifications about specific event.
    * It must implement necessary methods to receive and process these notifications.

Which containers use a border Layout as their default layout? | Core Java

any containers are there which is use border layout as their default layout. that are fillowing as :

• The window,
•  Frame and
•  Dialog classes .

What is an event handler ? | Core Java

An event handler is bassically is a part of a computer program, Which is created mainly for the programs, Its signifies the program how to act in response to a specific event.

What is an event? | Core Java

Event is bassically a changing the state of an object .

Why won't the JVM terminate when I close all the application windows? | Core Java

The AWT event dispatcher thread is not a daemon thread. You must explicitly call System.exit to terminate the JVM.

Which Swing methods are thread-safe? | Core Java

The only thread-safe methods are following here :

•  Repaint(),
•  Revalidate(), and
•  Invalidate()