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JavaFAQ Home » Mathematics
Integers are whole numbers, for example, -35, 0, 2048, .... Integers are
represented in binary inside the computer, and in decimal in Java source
programs. Java automatically converts decimal numbers you write in your source
program into binary numbers internally.
Four kinds of integers
The are four types of integers in Java:
long. The most common is int.
All integers are stored in signed, two's-complement, format.
char is an unsigned integer type altho it is used to
store characters. This is largely because of Java's legacy from C++. Don't use
char for integers unless you are sure of what you're doing.
How Java stores integers in memory
Java stores all integers in memory as binary numbers.
How to write integer literals
Here is how to write decimal integer literals (constants).
int literals are written in the usual decimal notation,
like 34 or -222.
long literals are written by adding an L (or lowercase l
altho this is almost impossible to distinguish from the digit 1), eg, 34L or
- There is no way to write a literal
altho sometimes Java will automatically cast an int literal to the
You can write an int in hexadecimal by prefixing the hexadecimal number with the
digit zero followed by the letter x, "0x" or "0X". The hexadecimal digits are
0-9 and the letters a-f in upper- or lowercase.
i = 0x2A; // assigns decimal 42 to i.
Operations may produce numbers which are too large (overflow) to be stored in an
int. No error is caused in this case; the result is simply an
incorrect number (one of the shames of modern computer arithmetic). Division by
zero will cause an execution exception (ArithmeticException).
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