Variables:
- Variable is a container which holds user data.
- Memory will be allocated for the variable while executing the program.
- Value of the variable can be changed any number of times during the program execution.
Syntax:
<data type> <var name>;
<data type> <var name> = <value>;
Example: Coming soon...
Types of variables:
There are two types of variables based on data type used to declare the variable.
Types of Variables:
There are various syntax for declaring variables
Types of variables:
There are two types of variables based on data type used to declare the variable.
- Primitive Variables
- Reference Variables
1. Primitive Variables: Variables declared with primitive data types are called primitive variables.
Ex.
int a;
int b = 99;
double d1;
double d2 = 9.9;
2. Reference Variables: Variables declared with user defined data types are called reference variables.
Ex.
String str1;
String str2 = "programingsoeasy";
Lab1.java
|
|
class Hello{
boolean b1;
byte b2;
short s;
int i;
long l;
float f;
double d;
String str;
Hello h;
void show(){
System.out.println(b1);
System.out.println(b2);
System.out.println(s);
System.out.println(i);
System.out.println(l);
System.out.println(f);
System.out.println(d);
System.out.println(str);
System.out.println(h);
}
}
|
class Lab1{
public static void main(String[] args){
Hello h = new Hello();
h.show();
}
}
|
Lab2.java
|
|
class Hello{
char ch;
void show(){
System.out.println(ch == 0);
System.out.println(ch == ‘’);
System.out.println(ch == ‘ \u0000’);
}
}
|
class Lab2{
public static void main(String[] args){
Hello h = new Hello();
h.show();
}
}
|
S.N.
|
Primitive
Variables
|
Reference
Variables
|
1
|
Variables declared with primitive data types are called primitive
variables.
|
Variables declared with reference data types are called reference
variables.
|
2
|
Memory allocation for primitive variables dependents on the primitive
data types.
|
Always 8 bytes of memory will be allocated for reference variables.
|
3
|
Default value for primitive variables depends on primitive data
types.
|
Always null will be assigned as default value for reference variables.
|
4
|
Primitive variables hold valid literals or value in the allocated
memory.
|
Reference variables hold either null or address of an object in the allocated
memory.
|
Types of Variables:
There are three types of variables based on the scope of the variables.
- Instance Variables
- Static Variables
- Local Variables
1. Instance Variables :
- Variables declared in the class without using static keyword are called as instance variables.
2. Static Variables:
- Variables declared in the class using static keyword are called as static variables.
3. Local Variables:
- Variables declared in the member of the class like method etc are called as local variables.
Other Core Java Articles:
1. Java Characteristics / features / buzzwords
2. Java basic questions
3. Java history / java editions / java versions
5. Java data types primitive and user defined1. Java Characteristics / features / buzzwords
2. Java basic questions
3. Java history / java editions / java versions
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