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

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 |

and 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 |

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 |

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 |

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 |

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);
```

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`

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;`

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);`

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);

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

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."

`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);
```

- 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?

- 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?