Java - Data Types

Data types define the type and value range of the data for the different types of variables, constants, method parameters, returns type, etc. The data type tells the compiler about the type of data to be stored and the required memory. To store and manipulate different types of data, all variables must have specified data types.

Java data types are categorized into two parts −

• Primitive Data Types
• Reference/Object Data Types

Java Primitive Data Types

Primitive data types are predefined by the language and named by a keyword. There are eight primitive data types supported by Java. Below is the list of the primitive data types:

• byte
• short
• int
• long
• float
• double
• boolean

Java byte Data Type

• Byte data type is an 8-bit signed two's complement integer

• Minimum value is -128 (-2^7)

• Maximum value is 127 (inclusive)(2^7 -1)

• Default value is 0

• Byte data type is used to save space in large arrays, mainly in place of integers, since a byte is four times smaller than an integer.

• Example − byte a = 100, byte b = -50

Java short Data Type

• Short data type is a 16-bit signed two's complement integer

• Minimum value is -32,768 (-2^15)

• Maximum value is 32,767 (inclusive) (2^15 -1)

• Short data type can also be used to save memory as byte data type. A short is 2 times smaller than an integer

• Default value is 0.

• Example − short s = 10000, short r = -20000

Java int Data Type

• Int data type is a 32-bit signed two's complement integer.

• Minimum value is - 2,147,483,648 (-2^31)

• Maximum value is 2,147,483,647(inclusive) (2^31 -1)

• Integer is generally used as the default data type for integral values unless there is a concern about memory.

• The default value is 0

• Example − int a = 100000, int b = -200000

Java long Data Type

• Long data type is a 64-bit signed two's complement integer
• Minimum value is -9,223,372,036,854,775,808(-2^63)
• Maximum value is 9,223,372,036,854,775,807 (inclusive)(2^63 -1)
• This type is used when a wider range than int is needed
• Default value is 0L
• Example − long a = 100000L, long b = -200000L

Java float Data Type

• Float data type is a single-precision 32-bit IEEE 754 floating point

• Float is mainly used to save memory in large arrays of floating point numbers

• Default value is 0.0f

• Float data type is never used for precise values such as currency

• Example − float f1 = 234.5f

Java double Data Type

• double data type is a double-precision 64-bit IEEE 754 floating point

• This data type is generally used as the default data type for decimal values, generally the default choice

• Double data type should never be used for precise values such as currency

• Default value is 0.0d

• Example − double d1 = 123.4

Java boolean Data Type

• boolean data type represents one bit of information

• There are only two possible values: true and false

• This data type is used for simple flags that track true/false conditions

• Default value is false

• Example − boolean one = true

Java char Data Type

• char data type is a single 16-bit Unicode character

• Minimum value is '\u0000' (or 0)

• Maximum value is '\uffff' (or 65,535 inclusive)

• Char data type is used to store any character

• Example − char letterA = 'A'

Example: Demonstrating Different Primitive Data Types

Following examples shows the usage of variour primitive data types we've discussed above. We've used add operations on numeric data types whereas boolean and char variables are printed as such.

public class JavaTester {
   public static void main(String args[]) {

      byte byteValue1 = 2;
      byte byteValue2 = 4;
      byte byteResult = (byte)(byteValue1 + byteValue2);

      System.out.println("Byte: " + byteResult);

      short shortValue1 = 2;
      short shortValue2 = 4;
      short shortResult = (short)(shortValue1 + shortValue2);

      System.out.println("Short: " + shortResult);

      int intValue1 = 2;
      int intValue2 = 4;
      int intResult = intValue1 + intValue2;

      System.out.println("Int: " + intResult);

      long longValue1 = 2L;
      long longValue2 = 4L;
      long longResult = longValue1 + longValue2;

      System.out.println("Long: " + longResult);

      float floatValue1 = 2.0f;
      float floatValue2 = 4.0f;
      float floatResult = floatValue1 + floatValue2;

      System.out.println("Float: " + floatResult);

      double doubleValue1 = 2.0;
      double doubleValue2 = 4.0;
      double doubleResult = doubleValue1 + doubleValue2;

      System.out.println("Double: " + doubleResult);

      boolean booleanValue = true;

      System.out.println("Boolean: " + booleanValue);

      char charValue = 'A';

      System.out.println("Char: " + charValue);     
   }
}

Output

Byte: 6
Short: 6
Int: 6
Long: 6
Float: 6.0
Double: 6.0
Boolean: true
Char: A

Java Reference/Object Data Type

The reference data types are created using defined constructors of the classes. They are used to access objects. These variables are declared to be of a specific type that cannot be changed. For example, Employee, Puppy, etc.

Class objects and various types of array variables come under reference datatype. The default value of any reference variable is null. A reference variable can be used to refer to any object of the declared type or any compatible type.

Example

The following example demonstrates the reference (or, object) data types.

// Creating an object of 'Animal' class
Animal animal = new Animal("giraffe");

// Creating an object of 'String' class
String myString = new String("Hello, World!");