Primitives

• Default type of an integer literal is int.
• Long can be specified by adding l or L
• Octal prefix with 0
• Hex prefix with 0x or 0X

• Floating point literals default type is double.

float pi = 3.14; // This will be a compiler error, because 3.14 is a fp literal which is double by default
double pi = 3.14; //OK
float pi = 3.14f; //OK

• Double can also be explicitly by adding the suffix d or D
• Float is denoted by suffix f or F

• Integers are stored in 2 complements's notation
• Leftmost bit is the sign bit, the remaining bits are used to store the value

e.g. of Byte

• Byte - 1 byte = 8 bits.
• Leftmost bit is to store the sign. So 7 bits are available for the value, so 2^7 = 128 values
• Negative range is -128 to -1 (128 numbers)
• Positive range is 0 to 127 (128 numbers, 0 is stored as a positive number)
• So a byte's range is -2^7 to (2^7 - 1)

• char's take up 2 bytes
• they are stored as unsigned 16-bit integers. This means they will represent a total of 2^16 positive values (0 to 65535 (2^16-1) )
• contrast with short which also uses 2 bytes. But it's max positive range is 2^15 -1. (Since 1 bit is to used to represent the sign)

Comments

• Comment start sequences like //, /*. /** are ignored within comment blocks.
• So trying to nest multiple-line comments will result in an error

/* This is the foo algorithm
   /* which takes foo's and sort's bars */
*/

Assignments

Watch out!

float f = 2;  //This is legal. 2 is an int which fits in a float.
float f = 2.0; //Illegal. 2.0 is a double which by default won't fit in a float.