This is the seventh lesson in a series introducing 10-year-olds to programming through Minecraft. Learn more here.

### Primitive Types

There are several types of variables that are part of the Java language; these are called primitive types. The most important ones for Minecraft are:

**char**: A single character (e.g. 'a', 'x')

**integer**: A whole number (e.g. -10, 0, 1, 145). It has a minimum value of -2,147,483,648 and maximum value of 2,147,483,647.

**float**: A decimal number (e.g. 3.62341, 1.5). Floats in Java are written with an 'f' or 'F' after them. For example:

```
float dirtHardness = 0.5f;
```

**boolean**: Either `true`

or `false`

.

### Arithmetic Expressions

Most of the expressions we'll use for Minecraft are addition and subtraction:

```
int x = 5;
int y = x - 3;
int z = y + 2;
```

In this case, `y`

would have a value of 2 and `z`

would have a value of 4. We can also perform multiplication and division.

### Boolean expressions

There are two ways to write boolean expressions: comparisons and boolean operators.

**Comparisons**

`>`

: greater than`<`

: less than`>=`

: greater than or equal to`<=`

: less than or equal to`==`

: equal to`!=`

: not equal to

Note: `=`

*assigns* a value to a variable, but `==`

*compares* two variables.

```
int x = 5;
int y = 2;
boolean isXGreaterThanY = x > y; // true
boolean isYLessThanOrEqualToX = y <= x; // true
```

**Boolean**

`!`

: Boolean NOT`&&`

: Boolean AND`||`

: Boolean inclusive OR`^`

: Boolean exclusive OR

We probably won't use `^`

very often.

```
int myAge = 34;
int yourAge = 18;
int dadsAge = 60;
// These all evaluate to true
boolean isYoungerThan50 = !myAge > 50;
boolean bothOfUsAreYoungerThan50 =
myAge < 50 && yourAge < 50;
boolean eitherOfUsIsYoungerThan50 =
myAge < 50 || dadsAge < 50;
```

Notice that a single *statement* can span multiple lines :) As long as you have the semicolon at the end, all is well.