Table of Contents
Variable and Data type in Java
In this article, we will discuss the concept of Variable and Data type in Java
Datatype
The data type and variables are an important concept in every programming language. A variable can be similar to a container, which holds the value of your program in Java. Every variable in Java has a data type that is identical to the compiler: what type of variable it and what type of data store it
Variable and Data type in Java language
There are two types of data type in Java
- Primitive data type
- Non-primitive data type
Classification of data type in Java
The variable is used to allocate and name the memory location to hold data.
To identify the storage memory location, each variable should be provided with a unique name.
Declaration int a; float b; String name; char letter; Initialization int a=10; //Here a is a integer type ,which takes the value 10 float b=24.67f; //Here a is a floating point type ,which takes the value 24.67 String name="kamalan"; //Here a is a String type,which takes the String "kamalan" char letter='a'; //Here a is a character type ,which takes the char "a"
Variables in memory location
- a is a memory address
- 10 is the value of the variable
Java has three types of variable
- Local
- Instant
- Static
Local
The local variable is a variable that is declared inside the method. It is called the local variable.
Instant /Global
The global variable is a variable that is declared inside the class but outside of the method. It is called instant variable/global variable
Static
A static variable is a variable that is declared as static using the static keyword,. It is called the static variable. It cannot be local.
Declaration and initialization
We can define a variable at two location inside the class.
for Example
Inside the class but outside the method – Global or Instance
Inside the class and inside the method – Local
Declare local and global variable inside the class
Example
Program 1
Variable declaration and displays its value in Java
Output 10 23.33 12.5 Kannan A
Program 2
Addition of Two numbers using variable
Output
Total is :25
Primitive Data types in Java
1. Data type – boolean
The boolean data type has two posible values true and false
Default Value – false
Default Size – 1 bit
Range – True or false
For example – boolean b=true
program
class BooleanEx{
public static void main(String args[]){
boolean isTrue=true;
System.out.print(isTrue);
}
}
When the above code is executed, The following output is displayed
true
2. Data type – char
it,s 16 bit unicode charactor
Default Value – ‘u0000’
Default Size – 2 byte
For example – char c=’A’
Program
class CharEx{
public static void main(String args[]){
char letter='A';
System.out.print(letter);
}
}
When the above code is executed, The following output is displayed
A
3. Data type – byte
It is used to apply int type data type to save memory
Default Value – 0
Default Size – 1 byte
Range – –126 to 127
For example – byteb=15;
Program
class ByteEx{
public static void main(String args[]){
byte num=124;
System.out.print(num);
}
}
When the above code is executed, The following output is displayed
124
4. Data type – short
It is used to apply int type data type to save memory
Default Value – 0
Default Size – 2 byte
Range – –32768 to 32767
For example – short s=1000;
Program
class ShortExample1{
public static void main(String args[]){
short num=1234;
System.out.print(num);
}
}
When the above code is executed, The following output is displayed
1234
5. Data type – int
Default Value – 0
Default Size – 4 byte
Range – –2147483648 to 2147483647
For example – int i=100;
Program
class Int_Ex1{
public static void main(String args[]){
int num=12345678;
System.out.print(num);
}
}
When the above code is executed, the following output is displayed
12345678
6. Data type – long
Default Value – 0L
Default Size – 8 byte
Range – –9223372036854775808 to 9223372036854775807
For example – long l=100;
Program
class Long_Ex1{
public static void main(String args[]){
long num=-1234567800L;
System.out.print(num);
}
}
When the above code is executed, the following output is displayed
-1234567800
7. Data type – float
Default Value – 0.0f
Default Size – 4 byte
Range –
For example – float f=34.5f;
Program
class Float_Ex1{
public static void main(String args[]){
float num=234.56f;
System.out.print(num);
}
}
When the above code is executed, the following output is displayed
234.56
8. Data type – double
Default Value – 0.0d
Default Size – 8 byte
Range – –32768 to 32767
For example – double d=56.78d;
class Double_Ex1{
public static void main(String args[]){
Double num=3433.56;
System.out.print(num);
}
}
When the above code is executed, the following output is displayed
3433.56
Non-primitive data types
- Array
- String