- Java's automatic floating point conversion in
arithmetic expressions:
- All floating point values (float and double) in an arithmetic operation (+, −, *, /) are converted to double type before the arithmetic operation in performed.
- Java's automatic integer conversion in
arithmetic operations:
-
All integer values
(byte, short and int)
in an arithmetic operations (+, −, *, /, %) are
converted to
int type
before the
arithmetic operation
in performed.
- However, if one of the values in an arithmetic operation (+, −, *, /, %) is long, then all values are converted to long type before the arithmetic operation in performed.
-
All integer values
(byte, short and int)
in an arithmetic operations (+, −, *, /, %) are
converted to
int type
before the
arithmetic operation
in performed.
- An very important
(but rarely taught) fact
about a computer:
- A computer can only operate on data of the same data type
- Java's
automatic conversion
in a mixed (integer and floating point)
arithmetic operation:
- All values in an mixed arithmetic operations (+, −, *, /, %) are converted to double type before the arithmetic operation in performed.
- Important note:
- The conversion rule is applied at the moment that the arithmetic operation is performed
- Example 1:
int a = 3; double b = 5.0, c; c = a + b; // a (int) is converted to a double // Then the addition is performed (on 2 doubles) - Example 2:
int a = 5, b = 2; double c = 5.0, d; d = c + a / b; // a/b is performed first. // Because a and b are integers, the division // a/b produces the quotient: a/b = 2 (not 2.5 !!!) // // Next we add: c + 2 // Because c is a double, the integer value 2 // is converted to double 2.0 // Result: 5.0 + 2.0 = 7.0 d = a + c / b; // c/b is performed first. // Because c is doube and Java will convert // b to double, and the division // c/b produces the quotient: c/b = 2.5 ! // // Next we add: a + 2.5 // // Result: 5.0 + 2.5 = 7.5
- What is the
type and
the value
printed by each of the
print statements in the following Java program:
public class Exercise2 { public static void main(String[] args) { short a = 5; int b = 2; double c = 1.0; double d = 5.0; System.out.println( a / b / c ); System.out.println( a / c / b ); System.out.println( a / b ); System.out.println( d / b ); System.out.println( (a + 0) / b ); System.out.println( (d + 0) / b ); System.out.println( (a + 0.0) / b ); System.out.println( (d + 0.0) / b ); } }Answers:
a / b / c = 2.0 (double) a / c / b = 2.5 (double) a / b = 2 (int) d / b = 2.5 (double) (a + 0) / b = 2 (int) (d + 0) / b = 2.5 (double) (a + 0.0) / b = 2.5 (double) (d + 0.0) / b = 2.5 (double)
- Example Program:
(Let the Java compiler teach you Java)
- Prog file: click here
How to run the program:
- Right click on link and
save in a scratch directory
- To compile: javac Exercise2.java
- To run: java Exercise2