Widening conversions do not lose information about the magnitude of a value.
For example, an int value is assigned to a double variable.
This conversion is legal because doubles are wider than ints.
Java's widening conversions are
From a byte to a short, an int, a long, a float, or a double
From a short to an int, a long, a float, or a double
From a char to an int, a long, a float, or a double
From an int to a long, a float, or a double
From a long to a float or a double
From a float to a double
Widening conversions:
char->int
byte->short->int->long->float->double
Here are the Type Promotion Rules:
All byte and short values are promoted to int.
If one operand is a long, the whole expression is promoted to long.
If one operand is a float, the entire expression is promoted to float.
If any of the operands is double, the result is double.
In the following code, f * b, b is promoted to a float and the result of the subexpression is float.
public class Main {
public static void main(String args[]) {
byte b = 4;
float f = 5.5f;
float result = (f * b);
System.out.println("f * b = " + result);
}
}
The output:
f * b = 22.0
In the following program, c is promoted to int, and the result is of type int.
public class Main {
public static void main(String args[]) {
char c = 'a';
int i = 50000;
int result = i / c;
System.out.println("i / c is " + result);
}
}
The output:
i / c is 515
In the following code the value of s is promoted to double, and the type of the subexpression is double.
public class Main {
public static void main(String args[]) {
short s = 1024;
double d = .1234;
double result = d * s;
System.out.println("d * s is " + result);
}
}
The output:
d * s is 126.3616