Java Constants

What are the java constants?

The java constants refers to fixed values that don’t change during the execution of a program. Java supports several types of constants as shown in diagram.

A programming language consists of data in the form of numbers, characters and strings, which provides output known as information.The program is sequence of instructions performs the task of processing data.

The instructions are formed using certain symbols and words according to some rules known as syntax rules.Every program instruction must perform conform precisely to the syntax rules of the language.

Integer Constants

An integer constant means the sequence of digits. In java There are 3 types of integer constants.

1. Decimal Integer :
   Decimal integers consist of a set of digits, 0 to 9, preceded by an optional minus sign ex- 975, -634,6632.

   NOTE : The spaces between digits are not allowed ex – 9 75, 9 3 5 etc.

2. Octal Integer :
   

   An octal integer constant consists of any combination of digits from 0 to 7. Ex- 873, 0, 04412:

3. Hexadecimal Integer :
   A sequence of digits preceded by 0x or ox considered as hexadecimal integer.
   The letter A, B, C, D, E, F are representing 10,11,12,13,14,15

Example

class IntConst
{
   public static void main(String args[])
   {
      int decimal = 8227;
      int octal = 0757;
      int hexadecimal = 0X1EF;
   }
}

Real Constants

Integer numbers are insufficient to represent numbers that vary continuously, such as temperature, heights, prices etc. number having fractional parts like 61.678 represents these quantities. Such numbers are called real constants.

Real number constant can include 4 parts

• Whole number
• Decimal point
• Fractional part
• Exponent part

these are shown in the decimal notation, having whole number followed by a decimal point and the fractional part, which is integer.
Ex- 0.0415, 901.12

Example

class RealConst
{
   public static void main(String args[])
   {
      float pi = 3.14f;
      double g = 9.8;
   }
}

Character constant (single character)

A character constant contains a single character like ‘s’, ‘1’,’@’ enclosed within single quotes. They require different data type to store. like char.

Example

class CharConst
{
   public static void main(String args[])
   {
      char myChar = 'A';
      char myChar2 = '@';
   }
}

String Constant

A string constant is a sequence or collection of characters and always enclosed between double quotes it can be characters, alphabets, digits, special characters and black spaces.
Ex- “AndroidBerry”, “@*!”, “javatutorials”

Example

class RealConst
{
   public static void main(String args[])
   {
      String Name = "Harry";
      String password = "@189*p";
   }
}

Backslash Constants

The backslash char constants are used with output statements for getting more effects like tab, new line, single quote, double quote, back slash etc.

Example

public class BackSlashDemo 
{
    public static void main(String[] args) 
    {
	System.out.println("1. AndroidBerry\b");
	System.out.println("2. AndroidBerry\f");
	System.out.println("3. Android\nBerry");
	System.out.println("4. Android\rBerry");
	System.out.println("5. Android\tBerry");
	System.out.println("6. \'AndroidBerry\'");
	System.out.println("7. \"AndroidBerry\"");
	System.out.println("8. AndroidBerry '\\'");		
    }
}

Output