Core Java MCQ Practice Questions
Java MCQ is one of the commonly used computer-programming tools used by programmers today. If you are a programmer seeking to become better in your line of duty, then this quiz will bring you closer to you goal.
- 1.What all gets printed when the following gets compiled and run? public class test { public static void main(String args[]) { int i=1, j=1; try { i++; j--; if(i/j > 1) i++; } catch(ArithmeticException e) { System.out.println(0); } catch(ArrayIndexOutOfBoundsException e) { System.out.println(1); } catch(Exception e) { System.out.println(2); } finally { System.out.println(3); } System.out.println(4); } } here
- A.
0 2 3 4
- B.
3 4
- C.
0 3 4
- D.
0 3
- 2.What will be the output of the program when to try to execute public class Arizona { int id; String name; public Arizona() { this(”aryabhatta”); System.out.print(”first “); } public Arizona(String name) { this(420, “aryabhatta”); System.out.print(”second “); } public Arizona(int id, String name) { this.id = id; this.name = name; System.out.print(”third “); } public static void main(String[] args) { Arizona b = new Arizona(); System.out.print(b.name +“ “ + b.id); } }
- A.
First second third aryabhatta 420
- B.
Third second first aryabhatta 0
- C.
Third second first aryabhatta 420
- D.
Compiler error
- 3.Consider the following code that contains the class definitions for class ABC, XYZ, and Alphabet. What will be the output of this code? class ABC extends XYZ { ABC () { super (); System.out.print (" ABC "); } public static void main (String args[]) { XYZ x1 = new ABC (); } } class XYZ extends Alphabet { XYZ () { System.out.print (" XYZ "); } } class Alphabet { void Alphabet () { System.out.print (" Alphabet "); } }
- A.
ABC XYZ Alphabet
- B.
XYZ ABC Alphabet
- C.
ABC XYZ
- D.
XYZ ABC
- 4.What will be the result of compiling and running the following code ? public class LoopCheck { public static void main(String args[]) { int i = 0; int x = 10; while ( x > 6 ) { System.out.print(++i + " "); x--; } } } Select the correct answer :
- A.
1 2 3 4 5
- B.
0 1 2 3 4
- C.
1 2 3 4
- D.
0 1 2 3
- 5.What all gets printed when the following program is compiled and run. Select the two correct answers. public class test { public static void main(String args[]) { int i, j=1; i = (j>1)?2:1; switch(i) { case 0: System.out.println(0); break; case 1: System.out.println(1); case 2: System.out.println(2); break; case 3: System.out.println(3); break; } } }
- A.
0
- B.
1 2
- C.
1
- D.
3
- 6.________________________ makes Java platform-independent.
- A.
JVM
- B.
Java syntax
- C.
Java API
- D.
Bytecodes
- 7.Byte b = 50 ; b = b * 2 ; System.out.println( " b = " + b ) ; The above fraction of code prints b = 100.
- A.
True
- B.
False
- 8.Final methods cannot be overridden but overloaded ?
- A.
True
- B.
False
- 9.Class Weather { static boolean isRaining; public static void main(String args[]) { System.out.print(isRaining); } }
- A.
Prints true
- B.
Prints false
- C.
Does not compile as boolean is not initialized
- D.
None
- 10.What is the name of the method used to start a thread execution?
- A.
Init();
- B.
Run();
- C.
Start();
- D.
Yield();
- 11.What is the output of following block of program ? boolean var = false; if(var = true) { System.out.println(“TRUE”); } else { System.out.println(“FALSE”); }
- A.
Prints TRUE
- B.
Prints FALSE
- C.
Compilation Error
- 12.Which interface provides the capability to store objects using a key-value pair?
- A.
Java.util.Set
- B.
Java.util.Map
- C.
Java.util.List
- D.
Java.util.Collection
- 13.What will be the output of the program? String s = "hello"; Object o = s; if( o.equals(s) ) { System.out.println("A"); } else { System.out.println("B"); } if( s.equals(o) ) { System.out.println("C"); } else { System.out.println("D"); } 1. A 2. B 3. C 4. D
- A.
2 and 4
- B.
1 and 2
- C.
3 and 4
- D.
1 and 3
- 14.What will be the output of the program? public class X { public static void main(String [] args) { try { badMethod(); System.out.print("A"); } catch (Exception ex) { System.out.print("B"); } finally { System.out.print("C"); } System.out.print("D"); } public static void badMethod() { throw new Error(); } }
- A.
ABCD
- B.
C is printed before exiting with an error message.
- C.
BC is printed before exiting with an error message.
- D.
Compilation Fails
- 15.Can there be an abstract class with no abstract methods in it?
- A.
Yes
- B.
No
- 16.What will be the output of the program? public class WithoutBook { static int x; boolean catch1() { x++; return true; } public static void main(String[] args) { if ((catch1() | catch1()) || catch1()) x++; System.out.println(x); } }
- A.
1
- B.
2
- C.
3
- D.
Compilation Error
- 17.What will be the output of the program? String s = "ABC"; s.toLowerCase(); s += "def"; System.out.println(s);
- A.
Abc
- B.
ABC
- C.
ABCdef
- D.
Compiler Error
- 18.What will be the output of the program? try { Float f1 = new Float("3.0"); int x = f1.intValue(); byte b = f1.byteValue(); double d = f1.doubleValue(); System.out.println(x + b + d); } catch (NumberFormatException e) { System.out.println("bad number"); }
- A.
Compilation fails on line 3.
- B.
Compilation fails on line 5.
- C.
Prints bad number
- D.
9.0
- 19.What will be the output of the program? String a = "newspaper"; a = a.substring(5,7); char b = a.charAt(1); a = a + b; System.out.println(a);
- A.
Apa
- B.
Apea
- C.
App
- D.
Apep
- 20.What should be at line number 3 to get the total sum of array "sum" ? public int totalSum( int[] sum ){ int a, b= 0 ; //which 'for' loop should be here(line :3) { b += sum[ a++ ] ; } return b ; }
- A.
For( a = 1 ; i
- B.
For( a= 0 ; a< sum.length ; )
- C.
For( a = 0 ; a< sum.length() ; a++ )
- D.
For( a = 0 ; a< sum.length ; a++ )
- 21.Public class Child extends Parent { public static void main(String[] args) { Parent p = new Child(); p.method(); } void method(){ System.out.println("Child method"); } } class Parent { void method(){ System.out.println("Parent method"); } } What is the output?
- A.
Compile time exception
- B.
Runtime exception
- C.
Child method
- D.
Parent method
- 22.What will be the output of the program? public class WBFoo { public static void main(String[] args) { try { return; } finally { System.out.println( "Finally" ); } } }
- A.
Finally
- B.
Compilation fails
- C.
An exception is thrown at runtime
- D.
The code runs with no output
- 23.Which of the following are true about interfaces. Select the correct answer.
- A.
Methods declared in interfaces are implicitly private.
- B.
Variables declared in interfaces are implicitly public, static, and final.
- C.
The keyword implements indicate that an interface inherits from another.
- D.
An interface can not extend any number of interfaces.
- 24.Which collection class allows you to associate its elements with key values, and allows you to retrieve objects in FIFO (first-in, first-out) sequence?
- A.
Java.util.ArrayList
- B.
Java.util.LinkedHashMap
- C.
Java.util.HashMap
- D.
Java.util.TreeMap
- 25.Public class CoreJavaOnlineTest1 { public static void main(String[] args) { String s1 = "withoutbook"; String s2 = s1; s1 = null; System.out.println("s1:"+s1+" s2:"+s2); } }
- A.
S1:null s2:withoutbook
- B.
S1:null s2:null
- C.
Exception
- D.
None of the above
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