# Rectangle
* Class header
* Instance variables
* Constructor
* Accessor: getWidth
* Method: area
---
# Square
* Class header
* Constructor
* etc.
---
# AddConstant
* Constructor, `addTo`, `setConstant`
* Knows constant to add
```java
{
AddConstant a = new AddConstant(5);
int x;
x = a.addTo(7); // gives x=12
x = a.addTo(80); // gives x=85
a.setConstant(3); // now does +3
x = a.addTo(7); // gives x=10
}
```
---
# RainbowBug
* Straight 5 steps
* Change color: red -> green -> blue
* Repeat color changes forever
## Instance variables?