Math operations

You can do mathematical operations on Java numbers and char. Java numbers are byte, short, int, long, float, and decimal.

Everything should be easy to understand. Two tricky part are division and modulus. Let’s go over them in details.

Division

When you divide an integer with an integer, then you will get an integer back which means it won’t have any decimal.

int x = 11;
int y = 2;

int result = 11/2; //result is 5 instead of 5.5

What you need to do is turn one of the number into a double.

int x = 11;
double y = 2;

int result = 11/2;

Or you can cast one of the number into a double.

int x = 11;
int y = 2;

int result = (double)11/2;

Modulus

The % sign is used to calculate the remainder of a number.

4 % 3 // returns 1 because 4 divides by 3 will yields a reminder of 1
5 % 3 // returns 2 because 5 divides by 3 will yields a reminder of 2
6 % 3 // returns 0 because 6 divides evenly into 3, therefore the remainder is 0

To check a number is divisible by another number, you check if the remainder is 0.

9 % 3 == 0; // 9 is divisible by 0

A number is even if it divides evenly into 2. Therefore, to check if it’s even, check if the remainder is 0.

number % 2 == 0; //number is even

A number is odd if it divides by 2 and the remainder is 1.

number % 2 == 1; //number is odd

Comparison Operators