Java Questions

Q:

class Hell {

public static void main(String[] args) {

Integer i = 42;

String s = (i<40)?"life":(i>50)?"base":"ball";

System.out.println(s);

}

}

A) null B) ball
C) base D) None
 
Answer & Explanation Answer: B) ball

Explanation:

D is correct. This is a ternary nested in a ternary with a little unboxing thrown in.Both of the ternary expressions are false.

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Q:

try { int x = Integer.parseInt("two"); }

Which could be used to create an appropriate catch block?

A) ClassCastException B) IllegalStateException
C) NumberFormatException D) None
 
Answer & Explanation Answer: C) NumberFormatException

Explanation:

C is correct. 'Integer.parseInt' can throw a NumberFormatException, and IllegalArgumentException is its superclass 

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Q:

void waitForSignal() {

Object obj = new Object();

synchronized (Thread.currentThread()) {

obj.wait();

obj.notify();

}

}

Which statement is true?

A) This code can throw an InterruptedException. B) This code can throw an IllegalMonitorStateException.
C) This code can throw a TimeoutException after ten minutes D) All the above
 
Answer & Explanation Answer: B) This code can throw an IllegalMonitorStateException.

Explanation:

It will throw  IllegalMonitorStateException.

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Q:

public abstract class Shape {

private int x;

private int y;

public abstract void draw();

public void setAnchor(int x, int y) {

this.x = x;

this.y = y;

}

}

Which two classes use the Shape class correctly?

A) public class Circle implements Shape { private int radius; B) public abstract class Circle extends Shape { private int radius; }
C) public class Circle extends Shape { private int radius; public void draw(); D) None
 
Answer & Explanation Answer: B) public abstract class Circle extends Shape { private int radius; }

Explanation:

Only B is true

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Q:

public class Threads2 implements Runnable {

public void run() {

System.out.println("run.");

throw new RuntimeException("Problem");

Which among the following is true?

}

public static void main(String[] args) {

Thread t = new Thread(new Threads2());

t.start();

System.out.println("End of method.");

}

}

A) java.lang.RuntimeException: Problem B) run. java.lang.RuntimeException: Problem
C) End of method. java.lang.RuntimeException: Problem D) End of method. run. java.lang.RuntimeException: Problem
 
Answer & Explanation Answer: D) End of method. run. java.lang.RuntimeException: Problem

Explanation:

Only D can be true

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Q:

Javascript is interpreted by

A) Server B) Object
C) Client D) None of the above
 
Answer & Explanation Answer: C) Client

Explanation:

JavaScript is an interpreted language, not a compiled language. A program such as C++ or Java needs to be compiled before it is run.

The source code is passed through a program called a compiler, which translates it into bytecode that the machine understands and can execute.

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Q:

main() {

int i;

printf("%d",scanf("%d",&i)); // value 10 is given as input here

}

A) 1 B) 2
C) 3 D) 4
 
Answer & Explanation Answer: A) 1

Explanation:

Scanf returns number of items successfully read and not 1/0. Here 10 is given as input which should have been scanned successfully. So number of items read is 1.

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Q:

 What is the string contained in s after following lines of code?

StringBuffer s = new StringBuffer(“Hello”); s.deleteCharAt(0);  ?

A) llo B) Hllo
C) ello D) H
 
Answer & Explanation Answer: C) ello

Explanation:

deleteCharAt() method deletes the character at the specified index location and returns the resulting StringBuffer object.

So after deleting the character at 0 ie 'H', the string returns 'ello' as the output.

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