Core Java 1

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1. What will be the output of the program? class Test { public static void main(String [] args) { int x=20; String sup = (x < 15) ? "small" : (x < 22)? "tiny" : "huge"; System.out.println(sup); } }

Small

Tiny

Huge

Compilation fails

About This Quiz

This questions are about the core java concepts includeing language fundamentals, objects,interfaces,threads,loops,collections and garbage collections. . .

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2. Which three guarantee that a thread will leave the running state?

yield()
wait()
notify()
notifyAll()
sleep(1000)
aLiveThread.join()
Thread.killThread()

1,2 and 4

2,5 and 6

3,4 and 7

4,5 and 7

3. 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() {}

ACD

ABCD

4. Public void test(int x) { int odd = 1; if(odd) /* Line 4 */ { System.out.println("odd"); } else { System.out.println("even"); } } Which statement is true?

Compilation fails

"odd" will always be output.

"even" will always be output.

"odd" will be output for odd values of x, and "even" for even values.

try

    int x = 0;

    int y = 5 / x;

catch (Exception e)

    System.out.println("Exception");

catch (ArithmeticException ae)

    System.out.println(" Arithmetic Exception");

System.out.println("finished");

State True or False: The output of the above code is the below Exception finished

True

False

6. Suppose that you would like to create an instance of a new Map that has an iteration order that is the same as the iteration order of an existing instance of a Map. Which concrete implementation of the Map interface should be used for the new instance?

TreeMap

HashMap

LinkedHashMap

The answer depends on the implementation of the existing instance.

7. Which four options describe the correct default values for array elements of the types indicated?

int -> 0
String -> "null"
Dog -> null
char -> '\u0000'
float -> 0.0f
boolean -> true

1,2,3,4

1,3,4,5

2,4,5,6

3,4,5,6

8. Class X implements Runnable { public static void main(String args[]) { /* Missing code? */ } public void run() {} } Which of the following line of code is suitable to start a thread ?

Thread t = new Thread(X);

Thread t = new Thread(X); t.start();

X run = new X(); Thread t = new Thread(run); t.start();

Thread t = new Thread(); x.run();

9. What will be the output of the program? class Bitwise { public static void main(String [] args) { int x = 11 & 9; int y = x ^ 3; System.out.println( y | 12 ); } }

10. Which of the following would compile without error?

Int a = Math.abs(-5);

Int b = Math.abs(5.0);

Int c = Math.abs(5.5F);

Int d = Math.abs(5L);

11. 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?

Java.util.ArrayList

Java.util.LinkedHashMap

Java.util.HashMap

Java.util.TreeMap

12. State the below statement is not false about static nested class: It's variables and methods must be static

True

False

13. Which three are valid declarations of a char?

char c1 = 064770;
char c2 = 'face';
char c3 = 0xbeef;
char c4 = \u0022;
char c5 = '\iface';
char c6 = '\uface';

1,2,4

1,3,6

3,5

5 only

14. Public class X { public static void main(String [] args) { X x = new X(); X x2 = m1(x); /* Line 6 */ X x4 = new X(); x2 = x4; /* Line 8 */ doComplexStuff(); } static X m1(X mx) { mx = new X(); return mx; } } After line 8 runs. how many objects are eligible for garbage collection?

15.

What is the output for the below code ?

public class A {

       public A() {

System.out.println("A");

public class B extends A implements Serializable {

       public B() {

        System.out.println("B");

public class Test {

       public static void main(String... args) throws Exception {

              B b = new B();

        ObjectOutputStream save = new ObjectOutputStream(new FileOutputStream("datafile"));

        save.writeObject(b);

        save.flush();

        ObjectInputStream restore = new ObjectInputStream(new FileInputStream("datafile"));

        B z = (B) restore.readObject();

}

A B A

A B A B

B B

A B

16. Public class Runner { public static void main(String args[]) { System.out.println("This is a correct program"); continue; } } State True or False: The above program prints a output

True

False

17. /* Missing Statement ? */ public class foo { public static void main(String[]args)throws Exception { java.io.PrintWriter out = new java.io.PrintWriter(); new java.io.OutputStreamWriter(System.out,true); out.println("Hello"); } } What line of code should replace the missing statement to make this program compile?

No statement required.

Import java.io.*;

Import java.io.PrintWriter;

#include java.io.*;

18. Public class Outer { public void someOuterMethod() { //Line 5 } public class Inner { } public static void main(String[] argv) { Outer ot = new Outer(); //Line 10 } }

Which of the following code fragments inserted, will allow to compile?

New Inner(); //At line 5

New Inner(); //At line 10

New ot.Inner(); //At line 10

New Outer.Inner(); //At line 10