Java Questions asked in various Companies Placement Papers

Java's which system allows a thread to enter a synchronized method on an object, and then wait there until some other thread explicitly notifies it to come out :-

Messaging

 

Packages act as containers for :-

Classes, Subordinate packages

 

Threads priorities are not integers that specify the relative priority of one thread to another.

False

 

When java program starts up, which thread begins running immediately?

Main thread

 

Java provides built-in support for which programming?

Multithreaded

 

The ________ is similar to break, except that instead of halting the execution of the loop, it starts the next iteration.

Continue

 

When can a constructor be called without specifying arguments?

When there are no constructors for the class

 

The mechanism which binds together the code and data and keeps both safe is ________.

Encapsulation

 

________ is an instance of a class that implements the runnable interface.

thread

 

Expression must be of the data types :-

Byte , Short , Int

 

Java define eight simple types of data byte, short, int, long, char, float, double, boolean.

True

 

What modifiers may be used with top-level class?

Public , Abstract , Final

 

Syntax to declare a variable in java is :-

type identifier [=value][,identifier[=value]…]

 

________ statement in java is conditional branch statement.

If

 

Which statement used inside a set of nested loops, will only break out of the innermost loop?

Break

 

In ________ statement condition is true, then statement 1 is executed.

If

 

The source for the frist package defines three classes

Protection , Derived , SamePackage

 

Java compiler stores the .class files in the path specified in CLASSPATH environmental variable.

False

 

Interface can be extended.

True

 

________ is the logical construct upon which the entire java language is built.

Class

 

Is it necessary to implement all the methods of an interface while implementing the interface

False

 

Which loops can be nested in java?

While, Do-while, For

 

Float data type is useful when we need fractional values.

True

 

What all the run( ) method can do?

Can call other method, Declare variable

 

Variable in an interface are implicitly final and static.

True

 

Which of the following operators are used in conjunction with the this and super references?

The dot operator

 

The ________ keyword halts the execution of the current loop and forces control out of the loop.

Break

 

What is a data structure that controls the state of a collection of threads as a whole?

Thread group

 

By Providing the interface keyword, Java allows you to fully utilize the which aspect of polymorphism?

One interface, Multiple methods

 

For externalizable objects the ________ is solely responsible for the external format of its contents.

Class

 

Which are the java's control statements?

For , If , Switch

 

What are the kinds of variables in Java?

Instance, local, class variables

 

Java Operators can be divided into these groups :-

Arithmetic , Bitwise , Relational

 

What is an array?

It is value collection of same type of data type

 

Modulus operator % can be applied to these data types :-

floating Point , Integer , Character

 

Start( )executes a call to ________.

run( )

 

________ is an instance of the class.

Object

 

________method starts a threrad by calling its run method.

start( )