Data Types in Java

There are basically eight primitive data types in Java which are can be looked as four categories:

• Integral: int, short, byte and long
• Floating point : float and double
• Logical : boolean
• Textual : char

1. Integer(int)

   The literals of integral type can be expressed using decimal, octal and hexadecimal forms. Some of the legal integer literals are:
   223
   -3460

   For octal (base 8), it is expressed with a leading zero (0) and it cannot include the digits 8 and 9. Some of them are:
   0377
   077

   int octalNuumber1=0377;
   int octalNumber2=077;
                                                       

   For hexadecimal, it is expressed with a 0x or 0X, using letters A to F s the additional digits required for base-16 numbers. Some are:
   0XCAFE
   0xABB

   int hexNumber1=0XCAFE;
   int hexNumber2=0xABB;
                                                       

   Java does not allow integer literals to be expressed in binary (base-2) notation. They are 32 bit int values unless they end with character L or l in which case they are 64 bit long.

   int intNumber=1454;
   long longNumber=1454L;
   long longOctal=047L;
   long longHex=0xefL;
                                                       

2. Floating point

   Float is 32 bit, single precision floating point value and double is 64 bit long, double precision. Some of which are:
   3.14
   123.56
   0.01

   It can use exponential or scientific notation which is a number followed by e or E and another number. The second number represents the power of ten by which the first number is multiplied. Some are:

   1.346E03     // 1.346 * 10^3
   1e-7         //1 * 10^-7

   Floating point literals are double by default. To include float, we have to follow the number by the character f or F.
   

   float number=2.465F  //float should be declared with suffix f or F
                                                       

3. Logical

   The boolean type represents a truth value. So there can be only two possible states- on or off/ yes or no/ true or false. boolean values can never be converted to or from other data types, especially integer.

   boolean name= true;    //declares name as boolean 
                          //and the value to be true.
                                                       

   
   

4. Textual

   There are two types- char and string. The char type represents Unicode characters and is 16 bit long. To include a character literal, just place it between apostrophes (single quotes).

   char c='B';
                                                       

   Escape Sequence	Character
   \b	backspace
   \n	New line
   \t	Vertical tab
   \f	Form Feed
   \r	Carriage Run
   \"	Double Quotes
   \\	Backslash
   \'	Single Quotes

   Strings are not a primitive data type but is a class. A string literal consists of arbitrary text within double quotes.

   String program= "hello world";
                                                       

Memory allocated for variables of each data type