Data Types in Java

Data Types in Java, Primitive Data Types, Non-primitive Data Types, Java Strings, Java Numbers, Java Characters, and Java Boolean Data Type.

Java Tutorial for Beginners

Java Data Types

What is Data Type?

Data Type is a classification of the type of data that a Variable or Constant or Method can hold in computer programming


Character, Number, Number with decimal values, Logical data, String, Date, Currency etc…

Note: Java supports explicit declaration of Data Types.

(We need to specify the Data Type before declaring Variables, Constants, and methods…)

Chatcter (char)
chat s=’Z’;

Number (byte, short, int, long, float, double)


String a= “X”;
String b=”Selenium”,
String c=”Automated Testing using Selenium”,

Logical data (boolean),


a. Variables

dataType variableName;
dataType variableName = value;
dataType variable1Name, variable2Name, variable3Name;
dataType variable1Name=value, variable2Name= value, variable3Name=value;


int a;
int b=100;
int c, d, e;
c=30; d=40; e=50;
int f=60, g=70, h=80;

b). Constants

Note: Variables and Constants are for holding the data, Variables may vary, but constants never change

int a;
a=100;//Correct for Variable
a=30; //Correct for Variable
final int b;
b=200; //Incorrect
final int c =300;//Correct
c=400; //Incorrect

c. Method with Return Value

public int add(){ //Return type is int (Non Static Method)
public static int multiply(){ //Return type is int (Static Method)
public void sub(){ //No return type (Non Static Method)
public static void divison(){ //No return type (Static Method)

Two Categories of Data Types in Java

1) Primitive Data Types
2) Non-primitive data Types

1. Primitive Data Types

a) Integer Data Types

i) byte (8 bits)

  • Minimum value is -128 (-2^7),
  • Maximum value is 127 (inclusive)(2^7 -1)
  • Default value is 0


byte a=100;
int x=100;
byte b=-129; //Out of Range
byte c=127;
byte d=128;//Out of Range

ii) short (16 bits)

  • Minimum value is -32,768 (-2^15)
  • Maximum value is 32,767 (inclusive) (2^15 -1)
  • Default value is 0.

short b=1000;

iii) int (32 bits)

  • Minimum value is – 2,147,483,648 (-2^31)
  • Maximum value is 2,147,483,647(inclusive) (2^31 -1)
  • The default value is 0


int a=1;
int b=1000;
int c= 100000000;
long d=9878787878l;//Out of Range

iv) long (64 bits)

  • 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)
  • Default value is 0L


long x=1000;
long y=999999999;
long z=3333333333l;

b) Relational Data Types (Numbers with Decimal Places)

v) float (32 bits)

float x = 10.23f;

vi) double (64 bits)
double y = 1234.5678765;

c) Character Data Type

vii) character

char z = ‘A’;
char s = ‘1’;
char r = ‘*’;

d) Conditional Data Type

viii) boolean

boolean k = true/false;

2. Non Primitive data types / Reference data types

Non Primitive data types in Java are Objects (String, Array etc…)


int a=100;
String b=”100″;
JavaExamples c = new JavaExamples();
123 – Integer Data Type
‘Y’ -Character
123.34 – float/double
“Selenium Testing” – String
“abc123*&^” – String
“123” – String
1 – Integer
‘1’ – Character

Converting Data / Data Conversion

Whenever we read data then the computer program considers that data as String type data, we need to convert the data in order to perform mathematical operations, Note: Generally we convert String type to Integer Type/ Relational type, we can’t convert Alpha bytes to numbers, etc…

String to Integer

String x=”100″

int num= Integer.parseInt(x);

String to Double

String y=”10.234″;

String num = Double.parseDouble(y);

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