Data Types

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  • The term data type refers to the type of data that can be stored in a variable.
  • Sometimes, Java is called a “strongly typed language” because when you declare a variable, you must specify the variable’s type.
  • Then the compiler ensures that you don’t try to assign data of the wrong type to the variable.
There are two data types available in Java:

  1. Primitive Data Types
  2. Reference/Object Data Types
Primitive Data Types
  • There are eight primitive data types supported by Java.
  • Primitive data types are predefined by the language and named by a keyword.
1. byte:
  • 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 int.
  • Example: byte a = 100 , byte b = -50
2. short:
  • 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 int
  • Default value is 0.
  • Example: short s = 10000, short r = -20000
3. int:
  • 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)
  • Int 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
4. long:
  • 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, int b = -200000L
5. float:
  • 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
6. double:
  • 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
7. boolean:
  • 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
8. char:
  • 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'

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