Tag: programming languages

Questions Related to programming languages

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(); } } }

technology programming languages

  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.

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Correct Option: B

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(); } } }
technology programming languages

  1. 9 0 9

  2. 9 7 9

  3. 0 0 0

  4. 0 7 0

Show answer
Correct Option: A

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()); } }
technology programming languages

  1. 7:30

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

  3. 12:50

  4. 19:45

Show answer
Correct Option: B

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(); } }
technology programming languages

  1. A B A

  2. A B A B

  3. B B

  4. A B

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Correct Option: A

. 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); } } }
technology programming languages

  1. Compile error

  2. One One Two Two

  3. One Two One Two

  4. One Two

Show answer
Correct Option: B

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"); } }
technology programming languages

  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

Show answer
Correct Option: B

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(); }
technology programming languages

  1. anonymous tech

  2. Compile Error

  3. Tech

  4. anonymous tech Tech

Show answer
Correct Option: A

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); } } } }

technology programming languages

  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

Show answer
Correct Option: B

AI Explanation

To answer this question, let's go through the 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);
      }
    }
  }
}

In this code, the class Outer contains a method doStuff() which declares a local variable z of type String.

Inside the doStuff() method, there is also a nested class Inner which has a method seeOuter().

The seeOuter() method tries to access the variables x and z from the enclosing Outer class. However, it is important to note that local variables, like z, are only accessible within the method they are declared in.

Therefore, when trying to access the local variable z from the seeOuter() method, it will result in a compile error because z is not in scope.

So, the correct answer is:

B. Compile Error

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; } }

technology programming languages

  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

Show answer
Correct Option: B

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); } }
technology programming languages

  1. das abcdef abcdef

  2. das das abcdef abcdef

  3. das abcdef

  4. abcdef abcdef

Show answer
Correct Option: A