Data Type and Variable in Java
In Java programming, we deal with a lot of data such as numbers, characters, floating points etc.
We use and
store all these data in programming purpose. All these data can be classified
into 8 basic types.
These 8
basic data types are also known as primitive data types.
Primitive
data types in Java:
We can store
many types of data such as integer, decimal, char, etc. There are total 8
primitive data types used in Java programming. These data types are listed as
follows.
Floating Data Type:
1. Float
2. Double
Integer Data Type:
3. Byte
4. Short
5. Integer
6. Long
Other Data Type:
7. Character data type
8. Boolean data type
Floating Data Type:
Floating
data type is data type which contains fractional numbers or floating numbers or
you can simply say the number which has decimal point. For example 4.5, 50.55,
etc.
Floating
data type is of two types –
1. Float data type
2. Double data type
The float
and the double data types are the same as they both contains fractional values.
The only difference is that, they own different storage capacities.
The double
data type can contain decimal numbers ranging between -1.7976931348623157 x 10308,
1.7976931348623157 x 10308
Double data
type takes 8 bytes of memory size to store floating digit number.
On the other
hand, a float data type can store numbers ranging between -3.4028235E38F,
3.4028235E38F and a float data type consumes 4 bytes of memory.
|
Data Type |
Number Range |
Memory Allocation |
|
Float |
-3.4028235E38F
to 3.4028235E38 |
4
Bytes |
|
Double |
(-)
1.7976931348623157 x 10308 to (+) 1.7976931348623157 x 10308 |
8
Bytes |
Use of float and Double data
types in Java Coding:
package JavaVariable;
public class JavaVariableClass {
public static void main(String[] args) {
float x = 3.4028235e38f;
double y =
1.7976931348623157e308d;
if(x>y) {
System.out.println("FLOAT is
greater than DOUBLE.");
}
else {
System.out.println("DOUBLE is greater
than FLOAT.");
}
}
}
Console Result:
DOUBLE is greater than FLOAT.
Integer data type:
Integer data
types are considered as those data which consists of numbers having no decimal point in between.
May it be a
positive or a negative number that does not create any difference. The only
condition that needs to be fulfilled to consider a number as an integer is that
the number should be a whole number.
Byte, short,
int, long these are various integer data types.
Byte is used
to store small integer data, whereas long data type is known for storing big
integer data.
Please use long, only when necessary otherwise
memory will be wasted. If you want to store small numbers, use short variable type or int variable
type.
|
Data Type |
Number Range |
Memory Allocation |
|
Byte |
-128
to 127 |
1
Byte |
|
Short |
-32768
to 32767 |
2
Bytes |
|
Int |
-2147483648
to 2147483647 |
4
Bytes |
|
Long |
-9223372036854775808
to 9223372036854775807 |
8
Bytes |
Character data type:
This Data
type represents single character value.
For example,
‘a’, ‘A’, ‘b’, ‘B’, ‘@’ etc.
When we
assign the value of any character
variable, we have to write the same inside a single quote.
The
character variable is declared by the word ‘char’.
Character data type consumes only 2 bytes in the memory space.
Boolean data type:
Boolean data
type contains only two values viz; true
and false.
So, this
data type is used to declare variables which store data to perform some
conditional tasks.
Boolean data type requires only 1-bit of memory space to store in a variable.
Binary Number
System:
In order to
understand data type and variable we should properly understand Binary system.
All numbers
/ values stored in computer are in the form of 1 or 0. This is binary number
system.
1-bit of a
memory can either contain a 0 or a 1. So it has 2 possible outcomes.
If there are
2 bits available in the memory, then there are 22 = 4 possible
outcomes.
For 3 bits
there are 23 = 8 possible outcomes.
(000, 001, 010, 011, 100, 101, 110, 111).
For n-bits
there are 2n possible outcomes.
For 8 bits
(1 byte) there are 28 = 256 possible outcomes.
So 8 bits
should contain numbers between 0 – 256, but it actually contains numbers
between -128 to 127 because, although in 1-bytes there are 8 bits but the 1st
bit (most significant bit) is a sign
bit.
1 denotes
(–ve) & 0 denotes (+ve) numbers.
So,
remaining 7 bits can contain number up to 27
= 128.
There are up
to 256 numbers only that can be
contained in 1 byte in total
including positive and negative numbers.
You can not
only take positive numbers, you will
require negative numbers also during
programming.
So, you can
store numbers between -27 to
+27.
Variables:
Variable is a location in memory which
contains data.
As the name
suggests, the data stored in a variable can be edited.
Without
variable we cannot access the data stored in the memory.
The variable
is assigned a name and by that name
we can access the variable and data.
Suppose we want
to store a number (say 30), then we need to assign a variable and into that
variable we have to store the number 30.
The variable must be assigned a name.
For
example, Variable name = roll_number
Data type of variable =
int
Value inside the
variable = 30
Now when we
what to access the variable, we have to look for the variable name and not the
variable value because there might be same value in multiple variables.
Variable
names are always unique.
See How data types and variable is
assigned in Java programming.
package JavaVariable;
public class JavaVariableClass {
public static void main(String[] args) {
byte x = 5;
int age = 20;
float percentageOfMarks = 10.5f;
double rateOfGrowth = 20.3873;
char alphabate = 'A';
boolean isSingle = true;
System.out.println(x);
System.out.println(age);
System.out.println(percentageOfMarks);
System.out.println(rateOfGrowth);
System.out.println(alphabate);
System.out.println(isSingle);
}
}
Result in Console:
5
20
10.5
20.3873
A
true
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