Data Types

Data type is a special keyword used to allocate sufficient memory space for the data.

Categories of data types

1.      Fundamental or primitive data types

2.      Derived data types

3.      User defined data types

1. Primitive data types

Primitive data types are those whose variables allows us to store only one value but they never allows us to store multiple values of same type.

Example

 int a; // valid

 a=10; // valid

a=10, 20, 30; // invalid

We have eight Primitive data type which are organized in four groups.

1. Integer category data types
2. Character category data types
3. Float category data types
4. Boolean category data types

1. Integer category data types

2. Character category data types

This data type takes two byte since it follows Unicode character set.

3. Float category data types

4. Boolean category data types

2. Derived data types

Derived data types are those whose variables allow us to store multiple values of same type. But they never allows to store multiple values of different types.

Example

int a[] = {10,20,30}; // valid

int b[] = {100, 'A', "ABC"}; // invalid

3. User defined data types

User defined data type related variables allows us to store multiple values either of same type or different type or both.

This is a data type whose variable can hold more than one value of dissimilar type.

Example

Student s = new Student();