All Types of Variables in Java

All Types of Variables in Java:

In Java we have different names for variable types such as class variable, static variable, member variable, block variable, instance variable & local variable. Sometimes we will get the confusion between these variables.

 

All Types of Variables in Java:

 

• Member Variable
• Class Variable
• Static Variable
• Instance Variable
• Block Variable
• Local Variable

 

 

Member variables are class variables.

Eg:

[java]

package in.javadomain;

public class MemberVariables {

// instance variable
int instanceMemberVariable;

// class variable/static variable
static int staticMemberVariable;

}

[/java]

 

Any variable declared for class level is called Member variable.

 

Member variables are of two types:

1. Static Member Variable/Static Variable/class variable

Class level variable declared with static keyword/static class level variables are called as static variable or class variable.

 

It will be shared between the different class instances/objects.

It is per class variable. Till the class live in the memory static variables are also alive.

 

2. Instance Member Variable/Instance Variable

Class level variable declard without static keyword/non-static class level variables are called as instance variable.

It is per instance/per object variable and it lives in the memory till the instance or object exist.

Local variable:

 

local variabls are created inside the functions/methods.

 

[java]

package in.javadomain;

public class LocalVariables {
public static void main(String[] args) {
int localVariable;
}
}

[/java]

 

 

Block variable:

 

Block variabls are created/declared/used inside the loops/blocks. Eg: for loop/if/else etc.

 

[java]

package in.javadomain;

public class BlockVariable {
public static void main(String[] args) {
for(int i=0;i<10;i++){
// i is a blockVariable here.
}
}
}

[/java]

 

Why static local variables are not allowed in java [or]

Why Can’t I declare a static variable inside the Main method?

Since static variables are shared between the different objects/instances, No use of allowing static variables inside the method, because it allows to keep the same static value in all the objects/instances whichever calls this method. Which looks not fair and waste. So static variables are allowed only in class level not for method levels.