The term variable is the combination of vari and able which means that we can change its values. The reserved area that is allocated in memory is known as variable and in simple words, the name of memory location is known as variable.
Java Variable
In Java, variables is a place which holds the value during the execution of Java programs. And each variable is assigned with a data type.
In java, there are three types of variables;
• Local
• Static
• Instance
Now, let's discuss these variables in detail.
Local Variable
Local variables are those variables which are declared inside the body of the method. In simple words we can say that local variable can be used by programmers only within the method and other methods will not be aware of its existence. And we can't define a local variable with static keyword.
Static Variable
Static variables are those variables which are declared as Static. Only during the loading of class memory allocation of static variable is possible. Static variable can't be local variable. You can share the static variable among the instance of the class by creating it's single copy.
Instance Variable
Instance variables are those variables which are declared outside the method but inside the class. The value of this variable is instance specific that's why it is known as instance variable.
Some examples of Java Variables are;
public class A
{
static int m=100;//static variable
void method()
{
int n=90;//local variable
}
public static void main(String args[])
{
int data=50;//instance variable
}
}//end of class• Add two numbers - Java variable example
public class Simple{
public static void main(String[] args){
int a=50;
int b=50;
int c=a+b;
System.out.println(c);
}
}Output
100• Widening - Java variable example
public class Simple{
public static void main(String[] args){
int a=50;
float f=a;
System.out.println(a);
System.out.println(f);
}}Output
50
50.0• Narrowing (Typecasting) - Java variable example
public class Simple{
public static void main(String[] args){
float f=50.5f;
//int a=f;//Compile time error
int a=(int)f;
System.out.println(f);
System.out.println(a);
}}Output
50.5
50• Overflow - Java variable example
class Simple{
public static void main(String[] args){
//Overflow
int a=150;
byte b=(byte)a;
System.out.println(a);
System.out.println(b);
}}Output
150
-106• Adding Lower Type - Java variable example
class Simple{
public static void main(String[] args){
byte a=50;
byte b=50;
//byte c=a+b;//Compile Time Error: because a+b=20 will be int
byte c=(byte)(a+b);
System.out.println(c);
}}Output
100• String - text are stored and written within the double quotes such as "Hello".
• int - integers are stored without decimals like 22.
• float - floating point numbers are stored including decimals like 2.55.
• char - single characters are stored and written within double quotes such as "A".
• boolean - value with two states are stored like yes or no.