Basics of Java Online Test

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Basics of Java

Description: Simple test to check your java
Number of Questions: 15
Created by:
Tags: java Conditional Statement

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Which type(s) of linked list is/are used in Java utility package?

Singly linked list
Doubly linked list
Circular linked list
All of the above
None of the above

Which of the following statements is wrong?

class superclass

{

}

class subclass extends superclass

{

}

superclass superclassref=new superclass();
superclass superclassref=new sublass();
subclass subclassref=new subclass();
subclass subclassref=new superclass();
Any class reference variable cannot reference other class object.

What happens in the heap memory when a subclass object is created?

Only for the subclass object, memory will be created.
Only for the superclass object, memory will be created.
Memory for both superclass and subclass will be created and also that memory is referenced by super class reference variable.
Memory for both superclass and subclass will be created and also that memory is referenced by subclass reference variable.
None of the above

Which of the following is a deprecated way to read input from standard input?

Using scanner
Using DataInputStream
Using BufferedReader
All of the above
None of the above

Which of the following statements is TRUE about Java interfaces?

It is not possible to implement interface in more than one class.
An interface should not have any members except abstract methods.
It is not possible to have reference variables for interfaces.
We cannot create object for interface.
If a class implements two interfaces which have the same method names, then the class should implement all the simlar methods in two interfaces twice.

Which of the following is not a checked exception?

IllegalAccessEception
CloneNotSupportedException
ClassNotFoundException
SecurityException
InstantiationException

Which of the following is the method in 'Cloneable' interface?

Copy()
Clone()
toString()
finalize()
None of the above

Which of the following statements is/are syntactically wrong?

Stack st=new Stack();
Stack st=new Stack<>();
Stack st<>new Stack();
Queue qq=new LinkedList();
All of the above

In which of the following cases will the finally block not be executed after the try block?

If try block does not have any exceptions.
If try block has a return statement.
If exception is not handled in catch block.
If try block has System.exit(0) statement.
All of the above

In which of the following cases can we serialize a function?

If the class does not implement serializable interface.
If it has transient keyword before it.
If it fails to create objects for 'ObjectOutputStream' and 'FileOutputStram'.
If it is overridden.
If it is static.

Which of the following is not legacy Class/Interface?

HashMap
Properties
Enumeration
Dictionary
Stack

Which of the following data types cannot be used with switch statement?

int
float
char
string
none of the above

Which of the following statements is false about Synchronized and ThreadSafety?

In multithreading, synchronized methods or statements used to fix dirty reading.
In Java, all the legacy classes are threadsafe.
Application consumes more time if it uses synchronized blocks.
In Java, we use Synchronized modifier to make a block as thread safe.
None of the above

What is the output of the above program?

public class Sss
{
public static
void main(String args[])
{
byte a=127; a++;
System.out.println(a);
}
}

127
0
128
- 128
Compilation error

What is the output of the above program?

public class A

{

static int a;

public static void main(String args[])

{

System.out.println(a);

}

Compilation error
0
Runtime error
NullpointerException
None of the above

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