Unit 1: Arithmetic Operators
Table of Contents
Arithmetic Operators
You know what computers are really good at? Crunching numbers. You can do basic arithmetic with Java by using arithmetic operators.
a = 1 + 1
b = 5 - 2
c = 2 * 10
d = 12 / 3
e = 10 / 3
f = 10.0 / 3
g = 10 % 3
System.out.println("a: " + a);
System.out.println("b: " + b);
System.out.println("c: " + c);
System.out.println("d: " + d);
System.out.println("e: " + e);
System.out.println("f: " + f);
System.out.println("g: " + g);
Note that you can concatenate some other types with strings, as you can see above.
Output:
a: 2
b: 3
c: 20
d: 4
e: 3
f: 3.333333333333
g: 1
Addition, Subtraction, Multiplication, & Division
Addition, subtraction, and multiplication are pretty straightforward. However, there are 2 types of division in Java: integer division and floating point division. Integer division happens whenever you divide 2 integers. This results in an integer since any decimals get truncated. Floating point division happens if you divide at least 1 floating point number, such as a double. (There are 2 floating point numeric types in Java, double and float. The former is more widely used.)
Modulus
You probably don’t recognize the % operator if you’ve never programmed before. This is the modulus operator, which gives you the remainder of a division. In the example, 10 % 3 equals 1 because 10 divided by 3 is 3 remainder 1.
Modulus is useful when you need to check if a number is divisible by another number (since the remainder would be 0) and for certain unit conversions.
Formatting
You can use string formatting to format output in a nice way. A common way to do this is using System.out.printf (you can think of this as print format).
In string formatting, we use special symbols as placeholders for certain data types.
| Symbol | Data Type |
|---|---|
%s | String |
%d | int, long |
%f | double, float |
For example:
double price = 5.36;
System.out.printf("The price is $%f", price);
Output:
The price is $5.36
Notice that %f is replaced by the value of price.
Note: System.out.printf does not automatically add a newline character (\n) to the end, so you may want to do that depending on how you want your output to look.
Note: You can basically have an infinite number of placeholders, in which case you need to separate each value by a comma. Also make sure that you put each value in the order that it appears in the string. For example:
int a = 5;
int b = 10;
System.out.printf("a is %d while b is %d", a, b);
Output:
a is 5 while b is 10
Note: If you want to display a certain amount of decimals for a floating point number, you can do something like this:
final double PI = 3.1415926;
System.out.printf("Pi is approximately %.2f", PI);
Output:
Pi is approximately 3.14
Notice that to display 2 decimals of precision, you prepend .2 to f. If you want to have 4 decimals of precision, write %.4f.
If you want to learn more about string formatting in Java, see this article.