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Java Programming DataTypes

Java DataType

The data stored in the memory of the computer can be of many types.

Data type specifies the size and type of values that can be stored in an identifier.

Different data types allow you to select the type appropriate to the needs of the application.

DataType Types

1) Primitive - which include Integer, Character, Boolean, and Floating Point.

2) Non-primitive - which include Classes, Interfaces, and Arrays.

Primitive DataTypes Chart

Type Size Value Example Literals
boolean 1 bit 0 or 1 true,false
byte 8 bits -128 to +127 byte n=100;
short 16 bits -32768 to + 32767
or -216 to 216-1		 short m=25000;
int 32 bits -232 to 232-1 int a=100000;
long 64 bits -264 to 264-1 long var=1000000000;
char 16 bits '\u0000' to '\uffff' char c='a';
char x='\u1010';
float 32 bits float i = 1.5f
float j = -1.23e100f
double 64 bits double x = 0.05d;
double y = 1.23456e300d;

Working with float and double

Syntax for float datatype

float a=10.5f;

Example:Print the value of float variable

public class FloatDemo {
   public static void main (String[] args) {
       float fval = 10.0f;
       System.out.println("Float Number : " + fval);
     }
}
Try it Yourself

Note: String and any number can be printed together using + in between values, as above. To print two strings we can use System.out.println(" Sun "+ "Light" );

Exercise :

Exercise 1: Finding Area of Circle. 

  double radius, pi, area;
      radius = 9.8;
      pi = 3.14;
      area = pi * radius * radius;
      System.out.println("Area of Circle with Radius "+ radius + " is : "+ area);
Do it Yourself

How to print a character in Java?

The char is a keyword which is used to store a single character such as 'a', 'Z', '9', '&', '$' and so on.

Character can be letters, digits or special symbols. Characters are always enclosed in single quotes .

We can also use ASCII code to represent value of character.To see ascii values click here

Syntax

char x = 'A';
char y = 65;  // Ascii code for char A is 65.

Example:Print the value of character variable

public class CharDemo {
   public static void main (String[] args) {
     char oneChar1 = 'A';
     char oneChar2 = 65;                      
     System.out.println(oneChar1);
     System.out.println(oneChar2);
    }
}

65 is the numeric representation of character 'A' , or its ASCII code.

Try it Yourself

Type Casting

When destination type is smaller than source type, then we need to explicitly cast it.

This is called as 'Type Casting'. This is also called narrowing conversion and truncation.

Syntax

(target-type) value

Example:Int to Byte Conversion

class IntToByteConversion
{
    public static void main(String arg[])
    {
        int a = 350;
        byte b;
        
        b = (byte) a;
        
        System.out.println("b = " + b );
    
    }
}
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Example:Data type casting

class DatatypeCasting
{
    public static void main(String arg[])
    {
        byte b;
        int i = 81;
        double d = 323.142;
        float f = 72.38f;
        char c = 'A';
        
        c = (char) i;
        System.out.println("i = " + i + " c = " + c);
        
        i = (int) d; 
        System.out.println("d = " + d + " i = " + i); 
        
        i = (int) f; 
        System.out.println("f = " + f + " i = " + i); 
        
        b = (byte) d;
        System.out.println("d = " + d + " b = " + b);
    
    }
}
Try it Yourself

Exercise:

10741.

Find the output of the following program 

public class asciicodes {
  public static void main(String args[]) {
     char var1 = 'A';
     char var2 = 'a';
     System.out.println((int)var1 + " " + (int)var2);
   } 
}
33 22
65 97
40 50
10 20

How to print boolean value in java?

A variable of boolean datatype can have two values: true and false (Boolean literals).

Boolean variables are used to indicate whether a condition is true or not, or to represent two states, such as a light being on or off.

Syntax

boolean a=true;

Example:Print the value of boolean variable

public class Demo {
   public static void main (String[] args) {
       boolean a = true;
       System.out.println(a);
     }
}
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Solve this!!

10742.
public class Demo {
   public static void main(String args[]) {
        boolean a=true;
        boolean b=false;
        System.out.println(a+" "+b);
    } 
}
true false
no value
true
error
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