• 2.3.1 Primitive data types
• 2.3.2 Literals
  • 2.3.2.1 boolean literals
  • 2.3.2.2 char literals
  • 2.3.2.3 Floating-point literals
  • 2.3.2.4 String literals
  
  
• 2.3.3 Constants
• 2.3.4 Reserved keywords

2.3 Variables, constants, and keywords

2.3.1 Primitive data types

• Java has built-in "primitive" data types.
• These primitives support integer, floating-point, boolean, and character values.
• The primitive data types of Java are:

• Samples:

    int i = 1;
    int age = 38;
    float balance = 1590.55;
    char a = 'a';
    boolean isTrue = true;
  

2.3.2 Literals

• A literal is a vlue that can be assigned to a primitive or string variable, or passed as an argument to a method call.

2.3.2.1 boolean literals

• true
• false
• boolean isTrue = true;

2.3.2.2 char literals

• 'n' - newline
• 'r' - return
• 't' - tab

2.3.2.3 Floating-point literals

• Expresses a floating-point numerical value.
• 3.1438 - a decimal point
• 4.33E+11 - E or e; scientific notation
• 1.282F - F or f; 32-bit float
• 1355D - D or d; 64-bit double

2.3.2.4 String literals

• A sequence of text enclosed in double quotes.
• String fourScore = "Four score and seven years ago";

2.3.3 Constants

• Constants are variables whose value does not change during the life of the object.
• Java does not have a constant keyword.
• In Java you define a constant like this:

    static final String name = "John Jones";
    static final float pi = 3.14159;
  

2.3.4 Reserved keywords

• Reserved Java keywords:

Fibonnaci program

• Here is a Fibonnaci program from The Java Programming Language:

  class Fibonacci {
     public static void main (String args[])
     {
        int lo = 1;
        int hi = 1;
        System.out.println(lo);
        while ( hi < 50 )
        {
           System.out.println(hi);
           hi = lo + hi;
           lo = hi - lo;
        }
    }
  }
  

• Type this code into the proper filename.
• Compile and run the program.
• Discuss the results.

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