Abstract Classes and Interfaces

In this session we look at how to use Abstract Classes and Interfaces in Object Oriented Design - especially as a way to get all the advantages of multiple inheritance without any of the problems.

Collections and Iterators

In this session we look at how we can use collection objects like ArrayList as a more advanced type of array. We also introduce the idea of generics (forcing a collection to hold a particular type) and see how Java handles the autoboxing and unboxing of primitives. Finally we look at Iterators, a common design pattern for dealing with iteration over a collection.

Computation Thinking

In this session we look at how to think systematically about a problem and create a solution. We look at the definition and characteristics of an algorithm, and see how through modularisation and decomposition we can then choose a set of methods to create. We also compare this somewhat procedural approach, with the way that design works in Object Oriented Systems.

Designing Applications

In this session we look at the how to use noun verb parsing to try and identify the building blocks of a problem, so that we can start to create object oriented solutions. We also look at some of the challenges of software engineering, and the processes that software engineers use to meet them, and finally we take a look at some more Design Patterns that may help us reuse well known and effective solutions in our own designs.

Encapsulation and Constructors

In this session we look at the public and protected keywords, and the principle of encapsulation. We also look at how Constructors can help you initialise objects, while maintaining the encapsulation principle.

The Java Library

In this session we point you at the Java Library, and go into some more details on how Strings work. We also introduce the HashMap class (a very useful type of collection).

Introduction to Java

In this lecture we look at key concepts in Java: how to write, compile and run Java programs, define a simple class, create a main method, and use if/else structures to define behaviour.

Loops and Arrays

In this session we look at the different types of loop in the Java language, and see how they can be used to iterate over Arrays.


In this session we look at how to create more powerful objects through more powerful methods. We look at parameters and call by value vs. call by reference; return types; and overloading.


In this session we build on inheritance and look at overriding methods and dynamic binding. Together these give us Polymorphism - the third pillar of Object Oriented Programming - and a very powerful feature that allows us to build methods that deal with superclasses, but whose calls get redirected when we pass in sub-classes.

Software Design

In this session we look at some of the basics of good code design, including avoiding duplication and designing for loose coupling and high cohesion.

Starting Out

In this lecture we describe the structure of the Programming Principles course at Southampton, look at the definitions and paradigms of programming, and take a look ahead to the key things that we will be covering in the weeks ahead.

Super and Sub-classes

In this session we introduce inheritance - one of the cornerstone concepts of object oriented programming. We look at how to define super and sub-classes, how to maintain encapsulation using the super() constructor, and why it is useful to use substitution to hold references to sub-classes in references typed as their super-class.

Testing and Debugging

In this session we look at the sorts of errors that occur in programs, and how we can use different testing and debugging strategies (such as unit testing and inspection) to track them down. These slides are based on Chapter 6 of the Book 'Objects First with BlueJ'.

Variables, Primitives, Objects and Scope

In this session we look more closely at the way that Java deals with variables, and in particular with the differences between primitives (basic types like int and char) and objects. We also take an initial look at the scoping rules in Java, which dictate the visibility of variables in your program.