Java Questioner for
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This document contains 30 multiple choice questions about Java programming concepts like I/O, data types, classes, threads, and more. It tests knowledge of Java keywords, syntax, and core APIs. The questions cover a wide range of fundamental and advanced Java topics including defining variables, writing classes, using control structures, creating and running threads, and working with strings, arrays, and other data types.
![keywords?
a) class, if, void, long, Int, continue
B) goto, instanceof, native, finally, default, throws
c) try, virtual, throw, final, volatile, transient
d) strictfp, constant, super, implements, do
17. Which will legally declare, construct, and initialize an array?
a) int [] myList = {"1", "2", "3"};
b) int [] myList = (5, 8, 2);
c) int myList [] [] = {4,9,7,0};
D) int myList [] = {4, 3, 7};
18. Which is a valid keyword in java?
A) Interface
b) String
c) Float
d) unsigned
public interface Foo
{
int k = 4; /* Line 3 */
}](https://image.slidesharecdn.com/javamcq-mahesh-120704034330-phpapp01/85/Java-Questioner-for-5-320.jpg)
![24. Which two are valid constructors for Thread?
1. Thread(Runnable r, String name)
2. Thread()
3. Thread(int priority)
4. Thread(Runnable r, ThreadGroup g)
5. Thread(Runnable r, int priority)
a) 1 and 3
b) 2 and 4
C) 1 and 2
d) 2 and 5
class X implements Runnable
{
public static void main(String args[])
{
/* Missing code? */
}
public void run() {}
}
25. Which of the following line of code is suitable to start a thread ?
a) Thread t = new Thread(X);
b) Thread t = new Thread(X); t.start();
C) X run = new X(); Thread t = new Thread(run); t.start();](https://image.slidesharecdn.com/javamcq-mahesh-120704034330-phpapp01/85/Java-Questioner-for-8-320.jpg)
Java Questioner for
- 1. 1. Which pair of function below is used for single character I/O? A) getchar() & putchar() b) scanf() & printf() c) Input () & output() d) None of these 2. Symbolic consists can be defined using? a) #define B) Const b) Symbols c) None of these 3. Null character is represented by? a) '(n)' b) '(o)' C) '(0)' d) '(e)' 4. Which among the following is a unconditional control structure? a) do-while b)if-else C) goto d) for
- 2. 5. Consider the following code snippet String river = new String(“Columbia”); System.out.println(river.length()); What is printed? a) 6 b) 7 C) 8 d) Columbia 6. Which of the following may be part of a class definition? a) instance variables b) instance methods c) constructors D) all of the above 7. What is different between a Java applet and a Java application? a) An application can in general be trusted whereas an applet can't. b) An applet must be executed in a browser environment. c) An applet is not able to access the files of the computer it runs on D) (A), (B) and (C). 8. Consider public class MyClass { public MyClass(){/*code*/} // more code... } To instantiate MyClass, you would write? A) MyClass mc = new MyClass(); b) MyClass mc = MyClass(); c) MyClass mc = MyClass; d) MyClass mc = new MyClass;
- 3. 9. What is byte code in the context of Java? A) The type of code generated by a Java compiler b) The type of code generated by a Java Virtual Machine c) It is another name for a Java source file d) It is the code written within the instance methods of a class. 10. How many JDBC driver types does Sun define? a) One b) Two c) Three D) Four 11. Who invented Java? a) Netscape b) Microsoft C) Sun d) None of the above is correct 12. To run a compiled Java program, the machine must have what loaded and running? A) Java virtual machine b) Java compiler c) Java bytecode
- 4. d) A Web browser 13. What is bytecode? a) Machine-specific code b) Java code C) Machine-independent code d) None of the above is correct 14. JDBC stands for: A) Java Database Connectivity b) Java Database Components c) Java Database Control d) None of the above is correct 15. Constructors are used to? A) Initialize the objects b) Construct the data members c) Both (1) & (2) d) None of these 16. Which one of these lists contains only Java programming language
- 5. keywords? a) class, if, void, long, Int, continue B) goto, instanceof, native, finally, default, throws c) try, virtual, throw, final, volatile, transient d) strictfp, constant, super, implements, do 17. Which will legally declare, construct, and initialize an array? a) int [] myList = {"1", "2", "3"}; b) int [] myList = (5, 8, 2); c) int myList [] [] = {4,9,7,0}; D) int myList [] = {4, 3, 7}; 18. Which is a valid keyword in java? A) Interface b) String c) Float d) unsigned public interface Foo { int k = 4; /* Line 3 */ }
- 6. 19. Which three piece of codes are equivalent to line 3? 1. final int k = 4; 2. public int k = 4; 3. static int k = 4; 4. abstract int k = 4; 5. volatile int k = 4; 6. protected int k = 4; A) 1, 2 and 3 b) 2, 3 and 4 c) 3, 4 and 5 d) 4, 5 and 6 20. Which three are valid declarations of a char? 1. char c1 = 064770; 2. char c2 = 'face'; 3. char c3 = 0xbeef; 4. char c4 = u0022; 5. char c5 = 'iface'; 6. char c6 = 'uface'; a) 1, 2, 4 B) 1, 3, 6
- 7. c) 3, 5 d) 5 only 21. Which one is a valid declaration of a boolean? a) boolean b1 = 0; b) boolean b2 = 'false'; C) boolean b3 = false; d) boolean b4 = Boolean.false(); 22. Which is a valid declarations of a String? A) String s1 = null; b) String s2 = 'null'; c) String s3 = (String) 'abc'; d) String s4 = (String) 'ufeed'; 23. What is the name of the method used to start a thread execution? a) init(); B) start(); c) run(); d) resume();
- 8. 24. Which two are valid constructors for Thread? 1. Thread(Runnable r, String name) 2. Thread() 3. Thread(int priority) 4. Thread(Runnable r, ThreadGroup g) 5. Thread(Runnable r, int priority) a) 1 and 3 b) 2 and 4 C) 1 and 2 d) 2 and 5 class X implements Runnable { public static void main(String args[]) { /* Missing code? */ } public void run() {} } 25. Which of the following line of code is suitable to start a thread ? a) Thread t = new Thread(X); b) Thread t = new Thread(X); t.start(); C) X run = new X(); Thread t = new Thread(run); t.start();
- 9. d) Thread t = new Thread(); x.run(); 26. Which cannot directly cause a thread to stop executing? a) Calling the SetPriority() method on a Thread object. b) Calling the wait() method on an object. C) Calling notify() method on an object. d) Calling read() method on an InputStream object. 27. Which two of the following methods are defined in class Thread? 1. start() 2. wait() 3. notify() 4. run() 5. terminate() A) 1 and 4 b) 2 and 3 c) 3 and 4 d) 2 and 4 28. Which of the following will directly stop the execution of a Thread? A) wait() b) notify() c) notifyall() d) exits synchronized code
- 10. 29. Which method must be defined by a class implementing the java.lang.Runnableinterface? a) void run() B) public void run() c) public void start() d) void run(int priority) 30. Which will contain the body of the thread? A) run(); b) start(); c) stop(); d) main();