Data types in Java: Primitive & Non-primitive


In this article, I will explain about datatypes in Java i.e. Primitive data types and Non-primitive data types, types of Primitive data types like int, byte, short, long, float, double, char, Boolean and types of Non-primitive data types like string, class, object, array. Also I will explain about types of variables in Java i.e. Instance variable, Local variable, Static variable.

Data types define the type of data. It also defines the memory allocation of that data type.

Data types in Java

There are two types of data types.
  1. Primitive
  2. Non-primitive

datatypes in java

Primitive data types

Primitive data types are pre-defined data types which are available in most of the programming languages. It represents a single value.
There are eight types of primitive data types. Int, byte, short, long, float, double, char, Boolean.
  • Integer Data types
    It represents integer data types i.e. numbers not having any decimal values. For example, 567, -2345 etc.
    It is sub divided into below types
    Byte, Short, Int, Long
    Data TypeMemory SizeDefault valueMinimum Value Maximum ValueExample
    Byte1 byte0-128+127Byte b=2
    Short2 bytes0-32768+32767Short s=2345
    Int4 bytes0-2147483648+2147483647Int i=25
    long8 bytes0L-9223372036854775808+9223372036854775807Long p=61234

  • Float data types
    This data type is use to save decimal point numbers. For example, 1.5, -456.56 etc.
    Float data types are divided into two sub types i.e. float and double.
    Data TypeMemory SizeDefault valueMinimum ValueMaximum ValueExample
    Float4 bytes0.0f-3.4e38 to -1.4e-451.4e-45 to 3.4e38Float x = 4.4f
    Double8 bytes0.0d-1.8e308 to -4.9e-3244.9e-324 to 1.8e308Double r=23.678

    Difference between float and double:
    Float represent up to 7 digits accurately after decimal point and double represent 15 digits accurately after decimal point.

  • Character data type
    Char is used to store character data type. It stores only one character at a time. For example, x, & etc.
    Data TypeMemory SizeDefault valueMinimum ValueMaximum ValueExample
    char2 bytes'\u0000'065535Char c='t'

  • Boolean data types
    Boolean data type has two values i.e. true and false.
    Example: Boolean b=false;

Non-primitive data type

Non-primitive data types are created by programmer. It is also called as 'Reference Variables' or 'Object reference' because it refers a memory location where data is stored. On the other hand, primitive data types stores value.
  • String
    • It is class in java provided with several methods used to store group of characters.
    • For example, abcd, india123 etc.
    • String is not a primitive data type because it has methods and only class can have methods. Primitive data types cannot have methods. So, String is a class which is non-primitive type.
    • 'String' is used to represent string class.
    • Example: String s="World"
  • Objects and Array
    Objects and Array are non-primitive data types because it refers to the memory location

Variables in Java

Variable is a name of memory location. Each variable has specific data type which determines size of memory.
There are three types of memory location.
  1. Instance variable:
    Variable which is defined within a class but outside the method is called as instance variable. Because each instance of class contains its own copy of these variables.

  2. Local variable:
    It is defined inside the method.

  3. Static variable:
    A variable which is declared as a static is called as static variable.
Example:
    public class PrintProgram {
        static int b;
        public static void main(String[] args) {
            int i;
            print();
        }
        static void print(){
            int x=1;
            System.out.println(i);
        }
    }

In above example, 'x' is a local variable, 'b' is a static variable and i is an instance variable.


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