Arithmetic and Assignment Operators

Arithmetic operators are used to modify the value of variables by performing math opperations on them. The (+) operator is used for addition. Let’s use our “MyVariables” program for this example.

public class MyVariables {
  public static void main(String[] args) {
    int myCoolVariable = 5 + 8;
    System.out.println(myCoolVariable);
  }
}

The (+) operator does its math and the output is “13.”

You can even use variable names with operators. Like this:

public class MyVariables {
  public static void main(String[] args) {
    int myCoolVariable = 5 + 8;
    myCoolVariable = myCoolVariable + 2;
    System.out.println(myCoolVariable);
  }
}

Now the output is “15.”

This (–) is the subtraction operator. This (*) is for multiplication. Use (/) for division. And this guy (%) is called the modulus operator. It is used to return the remainder of a division problem. Let’s check it out.

public class MyVariables {
  public static void main(String[] args) {
    int myCoolVariable = 10 % 3;
    System.out.println(myCoolVariable);
  }
}

The output now is “1” since 10 can be divided by 3 three times with a remainder of 1.

The last two arithmetic operators are the increment (++) and the decrement (— —) operators. The (++) increment will increase a variable’s value by 1, and the (— —) decrement will decrease a variable’s value by 1. Here is an example:

public class MyVariables {
  public static void main(String[] args) {
    int myCoolVariable = 3;
    myCoolVariable--;      //Decrease the value by 1.
    System.out.println(myCoolVariable);
  }
}

Now the output is “2.”

One final note about the (++) increment and (— —) decrement operators. They can be placed either before a variable name or after. The behavior is slightly different depending on where you place them. Look at this example:

public class MyVariables {
  public static void main(String[] args) {
    int myCoolVariable = 3;
    System.out.println(++myCoolVariable);
  }
}

Here the value of “myCoolVariable” gets increased by 1 and then output. So the output is “4.” But in this next example:

public class MyVariables {
  public static void main(String[] args) {
    int myCoolVariable = 3;
    System.out.println(myCoolVariable++);
  }
}

This time the output is “3” because “myCoolVariable” gets output first and then the value gets increased by 1.

You already know one of the assignment operators. The (=) is used to assign a value to a variable.

Another one is the (+=) operator. This operator takes the current value of a variable and adds to it. Like this:

public class MyVariables {
  public static void main(String[] args) {
    int myCoolVariable = 3;
    myCoolVariable += 5;
    System.out.println(myCoolVariable);
  }
}

The 5 gets added to “myCoolVariable.” Then the output is “8.”

The (-=) operator takes the current value of a variable and subtracts from it.

The (*=) operator takes the current value of a variable and multiplies it.

The (/=) operator takes the current value of a variable and divides it.

The (%=) operator takes the current value of a variable and divides it, then assigns the value of any remainder to the variable.

Challenge:

Look at this example:

public class MyVariables {
  public static void main(String[] args) {
    int myCoolVariable = 30;
    myCoolVariable %= 7;
    System.out.println(myCoolVariable++);
  }
}

Can you guess what the output will be?

Will the final value of “myCoolVariable” be the same as the output?

Next Topic: Comparison and Logical Operators