Inheritance and Data Structures in Java

We’ll start this module by talking about inheritance, a core concept in object-oriented programming. It’s the mechanism by which one class inherits the fields and methods of another class. Then we’ll learn about another aspect of polymorphism, overriding, which is creating a method in a subclass having the same signature as a method in a superclass. In particular, we’ll look at overriding the toString method for printing your objects and the equals method for comparing your objects, especially as it relates to unit testing. Finally, how you can restrict scope in a program by using modifiers to control access to variables, methods, and classes.

Did you know you can declare a method without defining it? It’s like giving a method a name, and even parameters and a return type, with no code in the body. These are called abstract methods. To define abstract methods, we’ll learn how to create abstract classes. With these new concepts and structures, we’ll continue to expand our Java knowledge and develop our programming skills. We’ll also learn how to better debug our programs by running them interactively using Eclipse’s Debugger. This will allow us to watch the source code and the variables, during execution.

There are multiple ways of loading and storing data in Java. Information can be stored and manipulated in different kinds of data structures. But data can also be stored in external files and then loaded into Java. In this module, we'll see how Java can communicate with the outside world by opening, reading from, and writing to, external files. This means of communication known as I/O or input/output, is extremely powerful with an overwhelming number of options. Any given I/O is not particularly difficult, but the difficulty lies in finding your way through the maze of possibilities. This module will help guide you through some of the different ways you can interact with external files. In addition, it will demonstrate methods you can use to handle errors and exceptions that may arise in your Java programs. In particular, when you're dealing with files.