Java Questions & Answers – ComponentEvent, ContainerEvent & FocusEvent Class

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This section of our 1000+ Java MCQs focuses 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
View Answer

Answer: a
Explanation: A ComponentEvent is generated when the size, position or visibility of a component is changed.
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2. Which of these events is generated when the component is added or removed?
a) ComponentEvent
b) ContainerEvent
c) FocusEvent
d) InputEvent
View Answer

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()
View Answer

Answer: d
Explanation: 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()
View Answer

Answer: b
Explanation: The getChild() method returns a reference to the component that was added to or removed from the container.
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5. Which of these are integer constants of ComponentEvent class?
a) COMPONENT_HIDDEN
b) COMPONENT_MOVED
c) COMPONENT_RESIZE
d) All of the mentioned
View Answer

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 loses input focus?
a) ComponentEvent
b) ContainerEvent
c) FocusEvent
d) InputEvent
View Answer

Answer: c
Explanation: None.

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

Answer: a
Explanation: None.
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8. Which of these methods can be used to know the type of focus change?
a) typeFocus()
b) typeEventFocus()
c) isTemporary()
d) isPermanent()
View Answer

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 is superclass of ContainerEvent class?
a) WindowEvent
b) ComponentEvent
c) ItemEvent
d) InputEvent
View Answer

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

Sanfoundry Global Education & Learning Series – Java Programming Language.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn