Interview Questions On Core Java Language Set-3

This set of objective questions in Java Language includes the collection of interview questions on core Java features and commands. It includes questions and answers on the different Java packages such as java.lang package, JAVA.awt package, and Java objects such as JAVA.awt.Component object, Label object, and the methods such as the paint() method, wait(), and notify() methods.

1) The CODE value in an ……… tag must name a class file that is in the same directory as the calling HTML page.
A. (applet)
B. >applet<
C. <applet>
D. <applet tag>

2) A class can be converted to a thread by implementing the interface ……….
A. Thread
B. Runnable
C. Start
D. Yield

3) Which of the following classes are not available in java.lang package?
A. Stack
B. Object
C. Math
D. String

4) State True or False for the following statements.
i) Reader class has a method that can read and return floats and doubles
ii) It is possible to use the File class to list the contents of the current the working directory
A. i-True, ii-False
B. i-False, ii-True
C. i-True, ii-True
D. i-False, ii-False

5) The setBackground() method is part of the following class in the JAVA.awt package.
A. Component
B. Graphics
C. Applet
D. Container

6) Which method is used to set the text of a Label object?
A. setText()
B. setLabel()
C. setTextLabel()
D. setLabelText()

7) Which of the following statement is/are True?
i) A Java monitor must either extend the Thread class or implement a Runnable interface
ii) The CheckboxGroup class is a subclass of the component class
A. i- only
B. ii- only
C. Both i and ii
D. None of the above

8) When we invoke repaint() for JAVA.awt.Component object, the AWT invokes the method …….
A. update()
B. draw()
C. show()
D. paint()

9) Which of the following methods are invoked by the AWT to support paint and repaint operations?
A. paint()
B. repaint()
C. draw()
D. redraw()

10) A thread can make a second thread ineligible for execution by calling the ……… method on the second thread.
A. second()
B. suspend()
C. append()
D. yield()

11) When we implement the Runnable interface, we must define the method
A. run()
B. start()
C. init()
D. main()

12) Which of the following are passed as an argument to the paint() method?
A. A Canvas object
B. A Graphics object
C. An image object
D. A paint object

13) State whether the following statements are True or False.
i) A class may be both abstract and final
ii) A final class may not have any abstract methods
iii) Frames and applets cannot be used together in the same program.
A. i-True, ii-True, iii-False
B. i-True, ii-False, iii-True
C. i-False, ii-True, iii-False
D. i-False, ii-True, iii-True

14) The methods wait() and notify() are defined in?
A. java.lang.String
B. java.lang.Object
C. java.lang.Runnable
D. java.lang.Thread

15) Which of the following components generates action events?
A. Buttons
B. Labels
C. Checkboxes
D. Windows

Read Also: Solved MCQ of JDBC and JSP set-1

16) Which javadoc tag is used to denote a comment for a method parameter?
A. @method
B. @parameter
C. @arjument
D. @param

17) Which of the following are not the wrapper classes?
A. Byte
B. Vector
C. Integer
D. Short

18) Which of the following classes is used to perform basic console I/O?
A. system
B. security Manager
C. math
D. runtime

19) Which of the following command line options generates documentation for all classes and methods?
A. -protected
B. -public
C. -private
D. -verbose

20) What is java_g used for?
A. Using the jdb tool
B. Executing a class with optimization turned off
C. To provide information about deprecated methods
D. None of the above

Answers:

1) C. <applet>
2) B. Runnable
3) A. Stack
4) A. i-True, ii-False
5) A. Component
6) A. setText()
7) D. None of the above
8) A. update()
9) A. paint()
10) C. append()
11) A. run()
12) B. A Graphics object
13) C. i-False, ii-True, iii-False
14) B. java.lang.Object
15) A. Buttons
16) D. @param
17) B. Vector
18) A. system
19) C. -Private
20) B. Executing a class with optimization turned off