Abstraction means ignoring details for the moment and concentrating on the problem at a higher level. Modularization comprises subdividing the problem into manageable parts each of which interacts in well-defined ways into the overall project.

Here we focus on the String class and investigate, through its methods, the types of operations we can do on a String.

Here we will cover some miscellaneous items such as static variables, static methods, Javadoc comments, debugger and compound assignment statements.

Use a set of objects from the shapes project to manually create a house object. Use existing Square, Circle and Triangle classes. Manually assemble component set to create and display initial design. Develop a new class Rectangle by refactoring Square class. Further refactor Circle and Triangle classes.

Develop a new class Tree using Rectangle and Triangle classes. Develop a new class Picture containing House, Circle (sun) and Tree fields.

Based on BlueJ ClockDisplay progressively develop NumberDisplay class to display a pair of digits to represent hours and minutes using the existing BlueJ class Clock to drive the ClockDisplay.