1.
What is
java?
Java is a high
level object oriented programming language. It consists of mainly classes and
objects. We can create any number of objects for a class. It was developed by
Sun Microsystems. It was developed by James Gosling in June 1991. There are a
lot of applications, websites, and games that are developed using java.
2.
What
are the primitive data types in java ?
|
Int
|
Double
|
|
float
|
Long
|
|
Char
|
Boolean
|
|
Short
|
byte
|
3.
List
some of features of java.
·
Simple – java
is easy to learn.
·
Object
oriented – Code reusability and maintenance will be good.
·
Portable
– java supports read once write any where. Java program is converted to
byte code which can run on any machine.
·
Platform
independent – java doesn’t depend on
operating system to get executed.
·
Secured –
java is secured because it doesn’t use
explicit pointers.
·
Robust – java
is a strong programming language as it uses strong memory management. The
concepts like garbage collector, exception handling make it more robust.
·
High
performance – As java uses ‘JIT – just in time’ compiler that reduces compile time.
4.
What
is type casting in java?
It is a process
of assigning a value of one primitive data type to another type.
Widening casting
Converting a smaller type to a larger type size.
Byte -> short -> char -> int -> long -> float
-> double
Narrow casting
Converting a larger type to a smaller size type
Double -> float -> long -> int -> char ->
short -> byte
5.
What
is JIT compiler ?
The compiler
used by the java for compiling is JIT compiler. It is mainly used to improve
the performance and reduces the amount of time needed for compilation.
6.
What
is function to find string length in java?
txt.length()
Example
String txt =
"KJIHGFEDCBA";
System.out.println("The
length of the txt string is: " + txt.length());
7.
Mention
some of the string methods in java.
txt.toUpperCase()
txt.toLowerCase()
txt.indexOf("sub-string"))
Example
String txt =
"Hello World";
System.out.println(txt.toUpperCase()); // Output
HELLO WORLD
System.out.println(txt.toLowerCase()); //
Output hello world
String txt =
"i love java and python";
System.out.println(txt.indexOf("and")); // Output 12
8.
Mention
some of the math functions in java.
·
Math.max(x,y)
·
Math.min(x,y)
·
Math.sqrt(x,y)
·
Math.abs(x)
·
Math.random()
9.
What
do you know about ‘break’?
The break
statement can be mainly in used in two forms.
1. Switch case
The break
is used to "jump out" of a switch statement.
2. Loops
The break
statement can also be used to “jump out” of a loop.
10.
What
do you know about ‘continue’ in java?
The continue
statement skips one iteration (in the loop), and continues with the next
iteration in the loop.
11.
What
is an array?
An array is a
collection of similar data type items stored at contiguous memory locations.
12.
Any
two applications of arrays.
·
Arrays can be used for CPU scheduling.
·
Used to implement other data structures like
Stacks, Queues, Heaps, Hash tables, etc.
- 13.
What
is method overloading?
In a class when
multiple methods have same name but different parameters.
NOTE
Return types may
or may not be same.
14.
Tell
about scope in java.
a. Method scope
Variables declared directly inside a method are
available in that method only.
b. Block scope
The code between curly braces {} is referred as a
block. Variables declared inside blocks are only accessible inside that specific block
only I mean between the curly braces.
15.
What
is recursion?
Recursion is the
technique of making a function call itself. This technique provides a way to
break complicated problems down into simple problems which are easier to solve.
16.
What
is ‘HALTING CONDITION’ ?
If we consider a
loop there is a problem called infinite looping. In recursion there is a
problem called infinite recursion. Infinite recursion is when the function
never stops calling itself. Every recursive function should have a halting
condition, which is the condition where the function stops calling itself.
17.
What
are various access specifiers in java?
a. Public
The classes, methods, or variables which are defined
as public, can be accessed by any class or method.
b. Protected
Protected can be accessed by the class of the same
package, or by the sub-class of this class, or within the same class.
c. Default
Default are accessible within the package only.
d. Private
The private class, methods, or variables defined as
private can be accessed within the class only.
18.
What is a package ?
Package in Java
is a mechanism to encapsulate a group of classes, sub packages and interfaces.
It is also
defined as collection of modules.
19.
