250+ TOP MCQs on ComponentEvent, ContainerEvent & FocusEvent Class and Answers

Java MCQs on ComponentEvent, ContainerEvent & FocusEvent Classes in Java Programming Language.

1. Which of these events is generated when the size of an event is changed?
a) ComponentEvent
b) ContainerEvent
c) FocusEvent
d) InputEvent

Answer: a
Clarification: 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
Clarification: 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
Clarification: None.

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
Clarification: 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
Clarification: 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 loses input focus?
a) ComponentEvent
b) ContainerEvent
c) FocusEvent
d) InputEvent

Answer: c
Clarification: None.

7. FocusEvent is subclass of which of these classes?
a) ComponentEvent
b) ContainerEvent
c) ItemEvent
d) InputEvent

Answer: a
Clarification: None.

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
Clarification: 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 is superclass of ContainerEvent class?
a) WindowEvent
b) ComponentEvent
c) ItemEvent
d) InputEvent

Answer: b
Clarification: ContainerEvent is superclass of ContainerEvent, FocusEvent, KeyEvent, MouseEvent and WindowEvent.

contest