Java
Data types, variables and Arrays
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Data types, variables and Arrays
Q:1) What is meant by variable?
Ans: Variables are locations in memory that can hold values. Before
assigning any value to a variable, it must be declared.
Q:2) What are the kinds of variables in Java? What are their uses?
Ans: Java has three kinds of variables namely, the instance variable, the
local variable and the class variable.
Local variables are used inside blocks as counters or in methods as
temporary variables and are used to store information needed by a single
method.
Instance variables are used to define attributes or the state of a
particular object and are used to store information needed by multiple
methods in the objects.
Class variables are global to a class and to all the instances of the
class and are useful for communicating between different objects of all
the same class or keeping track of global states.
Q:3) How are the variables declared?
Ans: Variables can be declared anywhere in the method definition and can
be initialized during their declaration. e.g.
int i; //declare the variable.
i=0; //Initialize the variable
They are commonly declared before
usage at the beginning of the definition.
Variables with the same data type can be declared together. Local
variables must be given a value before usage.
Q:4) What are variable types?
Ans: Variable types can be any data type that java supports, which
includes the eight primitive data types, the name of a class or interface
and an array.
Q:5)
How do you assign values to variables?
Ans: Values are assigned to variables using the assignment operator =.
e.g.
int i=0;
int i;
i=0;
Q:6) What is a literal? How many types of literals are there?
Ans: A literal represents a value of a certain type where the type
describes how that value behaves. There are different types of literals
namely number literals, character literals, boolean literals, string
literals, etc.
Q:7) What is an array?
Ans: An array is an object that stores a list of items
with same data type.
Q:8) How do you declare an array?
Ans: Array variable indicates the type of object that the array holds.
Ex: int arr[];
Q:9) Java supports multidimensional arrays.
a)True
b)False
Ans:
b.
Java Support Array of array. This mean we can assign an array into other
to make multidimensional. array.
Q:10) An array of arrays can be created.
a)True
b)False
Ans: a.
Q:11) What is a string?
Ans: A combination of characters is called as string.
The is a String class into lava.lang.* package which is used to
wrap any character to make a string.
Q:12) Strings are instances of the class String.
a)True
b)False
Ans: a.
Q:13) When a string literal is used in the program, Java automatically
creates instances of the string class.
a)True
b)False
Ans: a.
Q:14) Which operator is to create and concatenate strings?
Ans: Addition operator(+)
is used to concatenate strings.
Q:15) Which of the following declare an array of string objects?
a.
String[ ] s;
b.
String [ ]s:
c.
String[ s]:
d.
String s[ ]:
Ans: a, b and d
Q:16) What is the value of a[3] as the result of the following array
declaration?
a.1
b.2
c.3
d.4
Ans: d
Q:17) Which of the following are primitive types?
a.
byte
b.
String
c.
integer
d.
Float
Ans: a.
Explain:
String is not primitive data type .It is a String class which is used to
string values. Float is not as its capital letter of F. To declare integer
primitive values we have int primitive data type in java so it is not good
answer.
Q:18) What is the range of the char type?
a.
0 to 2 16
b.
0 to 2 15
c.
0 to 2 16-1
d.0 to 2 15-1
Ans: d
Q:19) What are primitive data types?
Ans:
Primitive data types are data type type
where we are going to store primtives value(e.g integer, short, float
,double ,long ,character, )There are 8 primitive data type in java. These
are
a.
byte, short, int, long
b. float, double
c.
boolean
d.char
Q:20) What are default values of different primitive types?
Ans:
int - 0
short - 0
byte - 0
long - 0 l
float - 0.0 f
double - 0.0 d
boolean - false
char - '\uoooo'
Q:21) Converting of primitive types to objects can be explicitly.
a)True
b)False
Ans: b.
Q:22) How do we change the values of the elements of the array?
Ans: The array subscript expression can be used to change the values of
the elements of the array.
Q:23) What is final
variable?
Ans: If a variable is declared as final variable, then you can not change
its value. It is just like becomes constant.
24) What is static variable?
Ans: Static variables are shared by all instances of a class.
Java
Data types, variables and Arrays
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Questions With Answers
