Arithmetic assignment Operators

The Simple Assignment Operator:

One of the most common operators that you'll encounter is the simple assignment operator "=". You saw this operator in the Bicycle class; it assigns the value on its right to the operand on its left:

int cadence = 0;
int speed = 0;
int gear = 1;

This operator can also be used on objects to assign object references, as discussed in Creating Objects.

The Arithmetic Operators:

The Java programming language provides operators that perform addition, subtraction, multiplication, and division. There's a good chance you'll recognize them by their counterparts in basic mathematics. The only symbol that might look new to you is "%", which divides one operand by another and returns the remainder as its result.

+ additive operator (also used for String concatenation)
- subtraction operator
* multiplication operator
/ division operator
% remainder operator

The following program, ArithmeticDemo, tests the arithmetic operators.

class ArithmeticDemo {

public static void main (String[] args){

int result = 1 + 2; // result is now 3
System.out.println(result);

result = result - 1; // result is now 2
System.out.println(result);

result = result * 2; // result is now 4
System.out.println(result);

result = result / 2; // result is now 2
System.out.println(result);

result = result + 8; // result is now 10
result = result % 7; // result is now 3
System.out.println(result);

}
}

You can also combine the arithmetic operators with the simple assignment operator to create compound assignments. For example, x+=1; and x=x+1; both increment the value of x by 1.

The + operator can also be used for concatenating (joining) two strings together, as shown in the following ConcatDemo program:

class ConcatDemo {
     public static void main(String[] args){
          String firstString = "This is";
          String secondString = " a concatenated string.";
          String thirdString = firstString+secondString;
          System.out.println(thirdString);
     }
}

By the end of this program, the variable thirdString contains "This is a concatenated string.", which gets printed to standard output.