Java Data Types

 

2 CHAPTER: DATA TYPES

            *Integers - This group includes byte, short, int and long, which are for whole value designed numbers.

        *Floating-point numbers- This group includes float and double, which represent numbers with fractional precision.

        *Characters - This group includes char, which represents symbols in a character set, like letters and numbers.

        *Boolean - This group includes boolean, which is a special type for representing true/false values.

 

// Compute no of seconds in 100 years.

File name : IntegerDemo.java

class IntegerDemo{

public static void main (String args[]){

 int years;

 int days;

 long nodays;

 long seconds;

 years = 100;

 days = 365;

 nodays=years * days;

 seconds =  nodays*24*60*60;

 System.out. println("No of seconds In"+years);

 System.out.println("years is : "+seconds);

}

}

Output

FLOAT:

Floating - point numbers are used for numbers with a decimal part. There are two floating-point types:float (32 bits, single-precision)and double (64bits,double-precision).       

            Type             Size                           Range

        double            64bits              1.7e-308to1.7e+308

         float               32bits              3.4e-038to3.4e+038

//Compute the area of a circle.

File name:DoubleDemo.java

class DoubleDemo{

        public static void main (String args[]){

        double a;

          float r=10.8f,pi=3.1416f;

           a=pi*r*r;

         System.out.println("Area of circle is"+a);

        }

}

output:

Character:

The char type is used for individual characters. Because java uses the Unicode character set, the type has 16 bits of precision,unsigned.

//Demonstrate char data type.

File name:CharDemo.java

class CharDemo{

       public static void main (String args[]){

            char ch1,ch2;

ch1=65;

ch2=ch1;

ch2++;

System.out.print("ch1 and ch2:");

System.out.println(ch1+" "+ch2);

}

}

 

output: 

Boolean:

Boolean type can have one of two values, true of false. Note that unlike in other C like languages, boolean is not a number, nor can it be treated as one. All tests of boolean variables should test for true or false.

//Demonstrate boolean values.

File name: BooleanDemo.java

class BooleanDemo{

public static void main (String args[]){

          boolean b;

        int x,y;

        b=false;

        x=30;

         y=20;

         b=x>y;

         System.out.println("x is greater than y:"+b);

          }

}

output:

Example:

File name: VarDeclaDemo.java

class VarDeclaDemo

{

public static void main (String args[])

{

int a=70;

short b=2;

float c=12.57f;

String name="Samuel";

System.out.println("The integer value is"+a);

System.out.println("The integer value is"+b);

System.out.println("The integer value is"+c);

System.out.println("The string value is"+ name);

}

}

The output appears as given below:

The Scope of Variables

File name: ScopeDemo.java

class ScopeDemo{

        public static void main (String args[]){

             int x;  //Known to all code within main

             x=10;

           {       //start new scope

                  

                        int y=20;       //known only to this block

                       //x and y both known here.

                      System.out.println("X="+x+"   Y="+y);

}

//x is still known here.

System.out.println("x  is "+x);

}

}

Output

Type Conversion and Casting

Converting one data Type into another data type is called Type Conversion.

File name: ConversionDemo.java

class ConversionDemo{

        public static void main (String args[]){

               byte b;

              int i= 257;

               System.out.println("\nConversion of int to byte.");

              b=(byte)i;

                System.out.println("i  ="+i+" and b="+b);

             }

}

This program generates the following output: