Java Basic Data Types

There are two data types available in Java:

• Primitive Data Types
• 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 key word. Let us now look into detail about the eight primitive data types.

byte:

• Byte data type is a 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

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

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

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

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

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

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

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'

Reference Data Types:

• Reference variables 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 type of array variables come under reference data type.
• 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 : Animal animal = new Animal("giraffe");

Creating an Object: As mentioned previously a class provides the blueprints for objects. So basically an object is created from a class. In java the new key word is used to create new objects. There are three steps when creating an object from a class: Declaration . A variable declaration with a variable name with an object type. Instantiation . The 'new' key word is used to create the object. Initialization . The 'new' keyword is followed by a call to a constructor. This call initializes the new object. Example of creating an object is given below:

public class Puppy{

   public Puppy(String name){
      // This constructor has one parameter, name.
      System.out.println("Passed Name is :" + name ); 
   }
   public static void main(String []args){
      // Following statement would create an object myPuppy
      Puppy myPuppy = new Puppy( "tommy" );
   }
}

Find Prime number by sqrt(JAVA)

import java.util.Scanner;
public class squire{
public static void main(String args[]){
Scanner shuvo=new Scanner(System.in);
int n,i=2;
System.out.println("Enter the number:");
n=shuvo.nextInt();
int temp= (int) Math.sqrt(n);
System.out.println(temp);
if(n%i==0)
{
System.out.println("The number is not prime");
}
else
{
   System.out.println("The number is prime");
}
}
}

Dual triangle by applet(JAVA)

import java.awt.*;
import java.applet.*;
/*
<applet code="HourGlass" width=230 height=210>
</applet>
*/
public class HourGlass extends Applet {
public void paint(Graphics g) {
int xpoints[] = {30, 200, 30, 200, 30};
int ypoints[] = {30, 30, 200, 200, 30};
int num = 5;
g.setColor(Color.red);
g.fillPolygon(xpoints, ypoints,num);
}
}

Rectangle(JAVA)

import java.awt.Graphics;
import java.awt.Color;
public class First extends java.applet.Applet
{
public void paint(Graphics g)
{
int width = 200;
int height = 200;
g.drawRect(0, 0, width, height);
}
}

Find the prime number(JAVA)

import java.util.Scanner;
public class prime{
public static void main(String args[]){
System.out.println("Enter digit:");
Scanner shuvo=new Scanner(System.in);
int i,j=1,n;
n=shuvo.nextInt();
for(i=2;i<=n/2;i++)
{

if(n%i==0)
{
j=0;
break;
}
}
if(j==0)
{
System.out.println("The number is not prime");
}
else
{
System.out.println("The number is prime");
}
}
}

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