Java Multiple Choice Questions & Answers on ComponentEvent, Container Event & FocusEvent Class for Freshers

1. Which of these events is generated when the size os an event is changed?

a) ComponentEvent
b) ContainerEvent
c) FocusEvent
d) InputEvent

Answer: a

Explanation: A ComponentEvent is generated when the size, position or visibility of a component is changed.

2. Which of these events is generated when the component is added or removed?

a) ComponentEvent
b) ContainerEvent
c) FocusEvent
d) InputEvent

Answer: b

Explanation: A ContainerEvent is generated when a component is added to or removed from a container. It has two integer constants COMPONENT_ADDED & COMPONENT_REMOVED.

3. Which of these methods can be used to obtain the reference to the container that generated a ContainerEvent?

a) getContainer()
b) getContainerCommand()
c) getActionEvent()
d) getContainerEvent()

Answer: d

4. Which of these methods can be used to get reference to a component that was removed from a container?

a) getComponent()
b) getchild()
c) getContainerComponent()
d) getComponentChild()

Answer: b

Explanation: The getChild() method returns a reference to the component that was added to or removed from the container.

5. Which of these are integer constants of ComponentEvent class?

a) COMPONENT_HIDDEN
b) COMPONENT_MOVED
c) COMPONENT_RESIZE
d) All of the mentioned

Answer: d

Explanation: The component event class defines 4 constants COMPONENT_HIDDEN, COMPONENT-MOVED, COMPONENT-RESIZE and COMPONENT-SHOWN.

6. Which of these events is generated when computer gains or losses input focus?

a) ComponentEvent
b) ContainerEvent
c) FocusEvent
d) InputEvent

Answer: c

7. FocusEvent is subclass of which of these classes?

a) ComponentEvent
b) ContainerEvent
c) ItemEvent
d) InputEvent

Answer: a

8. Which of these methods can be used to know the type of focus change?

a) typeFocus()
b) typeEventFocus()
c) isTemporary()
d) isPermanent()

Answer: c

Explanation: There are two types of focus events – permanent and temporary. The isTemporary() method indicates if this focus change is temporary, it returns a Boolean value.

9. Which of these events will be notified if scroll bar is manipulated?

a) ActionEvent
b) ComponentEvent
c) AdjustmentEvent
d) WindowEvent

Answer: c

Explanation: AdjustmentEvent is generated when a scroll bar is manipulated.

10. Which of these is superclass of ContainerEvent class?

a) WindowEvent
b) ComponentEvent
c) ItemEvent
d) InputEvent

Answer: b

Explanation: ContainerEvent is superclass of ContainerEvent, FocusEvent, KeyEvent, MouseEvent and WindowEvent.