# Lesson Goals

• Learn about the different operators and their functions.
• Become familiar with Java syntax.

## Write practice statements for the arithmetic operators

If variable a holds 10 and variable b holds 15, then:

Operator Operation Description Expression Result
+ addition adds two operands `a + b` 25
- subtraction subtracts second operand from the first `a - b` -5
* multiplication multiplies the operands `a * b` 150
/ division divides first operand by second operand `b / a` 1
% modulus (remainder) returns the remainder after integer division `b % a` 5

## Write practice statements for the incrementand decrement operators

If variable a holds the value 42, then:

Operator Operation Description Expression Equivalent to… `a`'s value afterwards
++ increment adds one to the value its `int` operand holds `a++` `a = a + 1` 43
‐‐ decrement subtracts one from the value its `int` operand holds `a--` `a = a - 1` 41

## Write practice statements for the equality operators

If variable a holds 10 and variable b holds 15, then:

Operator Operation Description Expression Result
== equal to evaluates to true if the two operands are equal `a == 10`
`a == b`
true
false
!= not equal to evaluates to true if the two operands are not equal `a != 10`
`a != b`
false
true

## Write practice statements for the relational operators

If variable a holds 10 and variable b holds 15, then:

Operator Operation Description Expression Result
> greater than evaluates to true of the first operand is greater than the second operand `a > b` false
>= greater than or equal to evaluates to true of the first operand is greater than or equal to the second operand `a >= b`
`a >= 10`
false
true
< less than evaluates to true of the first operand is less than the second operand `a < b` true
<= less than or equal to evaluates to true of the first operand is less than or equal to the second operand `a <= b`
`a <= 10`
true
true

## Write practice statements for the logical operators

If variable a holds `true` and variable b holds `false`, then:

Operator Operation Description Expression Result
&& conditional AND evaluates to true if both operands are true;
otherwise, evaluates to false
`a && b`
`a && true`
false
true
|| conditional OR evaluates to true if either operand is true;
otherwise, evaluates to false
`a || b`
`b || false`
true
false

# Translating English to Java

Let's translate English statements into Java. First, we'll do one together.

Start by writing the statements as comments. Here's an example:

``````// Jessica is 23 years old.
int jessicaAge = 23;

// Sam is 47.
int samAge = 47;

// Jessica is younger than Sam.
System.out.println(jessicaAge < samAge);
``````

## Let's break it down…

### Defining a variable to hold Jessica's age:

We need to create a variable to hold the age of Jessica. What should its type be?

`// Jessica is 23 years old.`

Since we think of ages as whole numbers, we will use an `int`:

`int jessicaAge`

## Let's break it down…

### Assigning a value for Jessica's age:

The word "is" means equals. How do we represent assignment?

`// Jessica is 23 years old.`

If Jessica "is 23", then Jessica's age = 23:

`int jessicaAge = 23;`

## Let's break it down…

### Comparing Jessica's and Sam's ages:

To say Jessica is younger than Sam means we are comparing their ages. Which operator would we use to compare them?

`// Jessica is younger than Sam.`

We use the "less than" relational operator to perform this comparison:

`System.out.println(jessicaAge < samAge);`

## Let's look at the syntax

Single line comments start with `//`:

```// Jessica is 23 years old. int jessicaAge = 23; // Sam is 47. int samAge = 47; // Jessica is younger than Sam. System.out.println(jessicaAge < samAge); ```

## Let's look at the syntax

Each statement ends with a semicolon. It acts like a period (.) in English at the end of a sentence.

```// Jessica is 23 years old. int jessicaAge = 23; // Sam is 47. int samAge = 47; // Jessica is younger than Sam. System.out.println(jessicaAge < samAge); ```

The statement:

``````int jessicaAge = 23;
``````

reads as "Jessica's age is 23."

## Let's look at the syntax

`println` is a method, so it ends with a set of opening and closing parentheses:

``` System.out.println(jessicaAge < samAge); ```

Inside the parentheses, we find the method arguments. For the `println` method, this is what we want to print. In this case, that's whether Jessica is younger than Sam:

``` System.out.println(jessicaAge < samAge); ```

## Your turn! Try translating these word problems into Java.

• Lisa is cooking muffins. The recipe calls for 7 cups of sugar. She has already put in 2 cups. How many more cups does she need to put in?
• At a restaurant, Mike and his three friends decided to divide the bill evenly. If each person paid \$13 then what was the total bill?
• How many packages of diapers can you buy with \$40 if one package costs \$8?
• Last Friday Trevon had \$29. Over the weekend he received some money for cleaning the attic. He now has \$41. How much money did he receive?
• Last week Julia ran 30 miles more than Pranav. Julia ran 47 miles. How many miles did Pranav run?
• How many boxes of envelopes can you buy with \$12 if one box costs \$3?
• After paying \$5.12 for a salad, Norachai has \$27.10. How much money did he have before buying the salad?

## Just keep coding! Just keep coding!

• 331 students went on a field trip. Six buses were filled and 7 students traveled in cars. How many students were in each bus?
• Aliyah had \$24 to spend on seven pencils. After buying them she had \$10. How much did each pencil cost?
• The sum of three consecutive numbers is 72. Print these numbers consecutively to the console.
• The sum of three consecutive even numbers is 48. What is the smallest of these numbers?
• Maria has boxes. She buys seven more. A week later, half of her boxes are destroyed in a fire, leaving her with 22 boxes. With how many did she start?