Data type:
- In the declaration of every variable, it is mandatory to specify its data type.
- Data type describes,
- The size of memory allocated to variable.
- The type of data allowed to store into variable.
Syntax:
- data_type variable_name = value ;
Example:
- int sum = 0;
- float balance = 3000.0;
- String name = “Amar”;
Data types classified into Primitive and Non-Primitive types.
Limits:
- A data type limit describes the minimum and maximum values we can store into a variable.
- Every data type is having size and it is represented by bytes
- One byte equals to 8 bits.
Integer types: We have 4 integer types among eight available primitive types in java.
| Type | Size(bytes) | Limits |
| byte | 1 | -128(-2^7) to +127(2^7-1) |
| short | 2 | -32,768(-2^15) to 32,767(2^15-1) |
| int | 4 | -2,147,483,648(-2^31) to 2,147,483,647(2^31-1) |
| long | 8 | -9,223,372,036,854,775,808(-2^63) to 9,223,372,036,854,775,807(2^63-1) |
Note:
- For every primitive type, there is a corresponding wrapper class.
- Wrapper classes providing pre-defined variables to find Size and Limits.
Program to print sizes of Integer types:
| class Sizes { public static void main(String[] args) { System.out.println(“Byte size : ” + Byte.SIZE/8 + ” bytes”); System.out.println(“Short size : ” + Short.SIZE/8 + ” bytes”); System.out.println(“Integer size : ” + Integer.SIZE/8 + ” bytes”); System.out.println(“Long size : ” + Long.SIZE/8 + ” bytes”); } } |
Program to print Limits of Integer types:
| class Limits { public static void main(String[] args) { System.out.println(“Byte min val : ” + Byte.MIN_VALUE); System.out.println(“Byte max val : ” + Byte.MAX_VALUE); System.out.println(“Short min val : ” + Short.MIN_VALUE); System.out.println(“Short max val : ” + Short.MAX_VALUE); } } |
Character data type: Character type variable is used to store alphabets, digits and symbols.
| class Code { public static void main(String[] args) { char x = ‘A’; char y = ‘5’; char z = ‘$’; System.out.println(“x val : ” + x + “\ny val : ” + y + “\nz val : ” + z); } } |
ASCII : Representation of each character of language using constant integer value.
| A-65 B-66 … … … Z-90 | a-97 b-98 …. …. …. z-122 | 0-48 1-49 .. .. .. 9-57 | *-34 #-35 $-36 … … … |