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programming languages Online Quiz - 32

Description: programming languages Online Quiz - 32
Number of Questions: 20
Created by:
Tags: programming languages

Can you call one constructor from another if a class has multiple constructors

  1. True

  2. False

Answer: 1

Key word "transient" is used so that the state of the object is not saved... (T/F)

  1. True

  2. False

Answer: 1

What are the new features added to Java 1.5?

  1. Boxing and UnBoxing

  2. Generics

  3. Enhanced for

  4. Iterator

Answer: 1,2,3

What is the output for the below code ? import java.util.LinkedList; import java.util.Queue; public class Test { public static void main(String... args) { Queue q = new LinkedList(); q.add("newyork"); q.add("ca"); q.add("texas"); show(q); } public static void show(Queue q) { q.add(new Integer(11)); while (!q.isEmpty ( ) ) System.out.print(q.poll() + " "); } }

  1. Compile error : Integer can't add

  2. newyork ca texas 11

  3. newyork ca texas

  4. newyork ca

Answer: 2

What is the output for the below code ? public class Test { public static void main(String argv[]){ ArrayList list = new ArrayList(); ArrayList listStr = list; ArrayList listBuf = list; listStr.add(0, "Hello"); StringBuffer buff = listBuf.get(0); System.out.println(buff.toString()); } }

  1. Hello

  2. Compile error

  3. java.lang.ClassCastException

  4. null

Answer: 3

Synchronized resizable-array implementation of the List interface is _____________?

  1. Vector

  2. ArrayList

  3. Hashtable

  4. HashMap

Answer: 1

What is the output for the below code ? public class NameBean { private String str; NameBean(String str ){ this.str = str; } public String toString() { return str; } } import java.util.HashSet; public class CollClient { public static void main(String ... sss) { HashSet myMap = new HashSet(); String s1 = new String("das"); String s2 = new String("das"); NameBean s3 = new NameBean("abcdef"); NameBean s4 = new NameBean("abcdef"); myMap.add(s1); myMap.add(s2); myMap.add(s3); myMap.add(s4); System.out.println(myMap); } }

  1. das abcdef abcdef

  2. das das abcdef abcdef

  3. das abcdef

  4. abcdef abcdef

Answer: 1

What is the output for the below code ? public class Test { public static void main(String... args) { for(int i = 2; i < 4; i++) for(int j = 2; j < 4; j++) assert i!=j : i; } }

  1. The class compiles and runs, but does not print anything.

  2. The number 2 gets printed with AssertionError

  3. The number 3 gets printed with AssertionError

  4. compile error

Answer: 2

What is the output for the below code ? public class Outer { private String x = "Outer variable"; void doStuff() { String z = "local variable"; class Inner { public void seeOuter() { System.out.println("Outer x is " + x); System.out.println("Local variable z is " + z); } } } }

  1. Outer x is Outer variable.

  2. Compile Error

  3. Local variable z is local variable

  4. Outer x is Outer variable Local variable z is local variable

Answer: 2

What is the output for the below code ? public class Tech { public void tech() { System.out.println("Tech"); } } public class Atech { Tech a = new Tech() { public void tech() { System.out.println("anonymous tech"); } }; public void dothis() { a.tech(); } public static void main(String... args){ Atech atech = new Atech(); atech.dothis(); }

  1. anonymous tech

  2. Compile Error

  3. Tech

  4. anonymous tech Tech

Answer: 1

What is the output for the below code ? public class Test extends Thread{ public static void main(String argv[]){ Test b = new Test(); b.start(); } public void run(){ System.out.println("Running"); } }

  1. Compilation clean and run but no output

  2. Compilation and run with the output "Running"

  3. Compile time error with complaint of no Thread import

  4. Compile time error with complaint of no access to Thread package

Answer: 2

. What is the output for the below code ? public class Test{ public static void main(String argv[]){ Test1 pm1 = new Test1("One"); pm1.run(); Test1 pm2 = new Test1("Two"); pm2.run(); } } class Test1 extends Thread{ private String sTname=""; Test1(String s){ sTname = s; } public void run(){ for(int i =0; i < 2 ; i++){ try{ sleep(1000); }catch(InterruptedException e){} yield(); System.out.println(sTname); } } }

  1. Compile error

  2. One One Two Two

  3. One Two One Two

  4. One Two

Answer: 2

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(); } }

  1. A B A

  2. A B A B

  3. B B

  4. A B

Answer: 1

What is the output for the below code ? public enum Test { BREAKFAST(7, 30), LUNCH(12, 15), DINNER(19, 45); private int hh; private int mm; Test(int hh, int mm) { assert (hh >= 0 && hh <= 23) : "Illegal hour."; assert (mm >= 0 && mm <= 59) : "Illegal mins."; this.hh = hh; this.mm = mm; } public int getHour() { return hh; } public int getMins() { return mm; } public static void main(String args[]){ Test t = new BREAKFAST; System.out.println(t.getHour() +":"+t.getMins()); } }

  1. 7:30

  2. Compile Error - an enum cannot be instantiated using the new operator

  3. 12:50

  4. 19:45

Answer: 2

What is the output for the below code running in the same JVM? public class A implements Serializable { transient int a = 7; static int b = 9; } public class B implements Serializable { public static void main(String... args){ A a = new A(); try { ObjectOutputStream os = new ObjectOutputStream( new FileOutputStream("test.ser")); os.writeObject(a); os. close(); System.out.print( + + a.b + " "); ObjectInputStream is = new ObjectInputStream(new FileInputStream("test.ser")); A s2 = (A)is.readObject(); is.close(); System.out.println(s2.a + " " + s2.b); } catch (Exception x) { x.printStackTrace(); } } }

  1. 9 0 9

  2. 9 7 9

  3. 0 0 0

  4. 0 7 0

Answer: 1

What is the output for the below code ? public class A {} public class B implements Serializable { A a = new A(); public static void main(String... args){ B b = new B(); try{ FileOutputStream fs = new FileOutputStream("b.ser"); ObjectOutputStream os = new ObjectOutputStream(fs); os.writeObject(b); os.close(); }catch(Exception e){ e.printStackTrace(); } } }

  1. Compilation Fail

  2. java.io.NotSerializableException: Because class A is not Serializable

  3. Run properly

  4. Compilation Fail : Because class A is not Serializable.

Answer: 2

What is the output for the below code ? public class Test extends Thread{ static String sName = "good"; public static void main(String argv[]){ Test t = new Test(); t.nameTest(sName); System.out.println(sName); } public void nameTest(String sName){ sName = sName + " idea "; start(); } public void run(){ for(int i=0;i < 4; i++){ sName = sName + " " + i; } } }

  1. good

  2. good idea

  3. good idea good idea

  4. good 0 good 0 1

Answer: 1

What is the output for the below code ? public class Test { public static void main(String... args) { Pattern p = Pattern.compile("a{3}b?c*"); Matcher m = p.matcher("aaab"); boolean b = m.matches(); System.out.println(b); } }

  1. true

  2. Compile Error

  3. false

  4. NullPointerException

Answer: 1

given x = y--; What will be true after execution?

  1. x>y

  2. x

  3. x==y

  4. x++

Answer: 1

Can a subclass access the private values of the super class

  1. No

  2. Yes

  3. Will have to use an instance

  4. None

Answer: 1
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