ogp-notes

Object-Oriented Programming

• Introduction: Topic of the course
• Principles of programming in Java
  • Concepts: values, variables, types, methods, parameters, arguments, return values, classes, fields, objects, object creation, object references, method activations and the call stack

Single-object abstractions

• First steps in modular programming Part 1 Part 2
  • Example: squareroot
  • Example: max3
  • Example: timeofday
  • Concepts: Using Eclipse, creating JUnit test cases, creating classes, instance methods, encapsulation, private versus public, using Git, constructors, unit testing basics and best practices
• Managing complexity through modularity and abstraction
  • Concepts: modularity, abstraction, API, client module, importance of documentation, information hiding, procedural abstraction, data abstraction, immutable versus mutable abstractions, abstract value/state of an object, Java’s built-in datatypes and operators
• Representation objects and representation exposure
  • Concepts: representation object, representation exposure
• How to properly document single-object abstractions
  • Concepts: defensive programming, contractual programming, preconditions, postconditions, class representation invariants (= private class invariants), class abstract state invariants (= public class invariants), getters, mutators

Inheritance

• Polymorphism
  • Concepts: abstract classes, polymorphism, subclassing, inheritance, instanceof, the static type checker, static/dynamic type of a variable or an expression, typecasts, pattern matching; class Object, autoboxing and -unboxing
• Dynamic binding
  • Concepts: dynamic binding, abstract methods, method overriding, @Override; methods equals, hashCode, toString, getClass; record classes
• Behavioral subtyping: modular reasoning about programs that use dynamic binding
  • Example: intlist_inheritance
  • Concepts: Non-modular reasoning, modular reasoning, method specifications, correctness of methods; method call resolution, resolved method vs called method, static versus dynamic method call binding; strenghtening of specifications, behavioral types, behavioral subtyping
• Interfaces
  • Concepts: interfaces, multiple inheritance, static fields, the Singleton pattern
• Implementation inheritance
  • Concepts: Inheritance of fields and methods, super constructor calls, super method calls
• Closed types
  • Concepts: types with a closed set of instances, enum classes, types with a closed set of direct subtypes, sealed types, switch statements and expressions
• Lists, sets, and maps
  • Concepts: the List, Set, and Map abstract datatypes (ADTs); the ArrayList, LinkedList, HashSet, and HashMap data structures; the Java Collections Framework

Multi-object abstractions (= entity-relationship abstractions)

• Single-class entity-relationship abstractions
  • Example: html
  • Concepts: entity graphs, multi-object abstractions, bidirectional associations, consistency of bidirectional associations, peer objects, peer groups
• Multi-class entity-relationship abstractions
  • Concepts: packages, package-accessible fields/constructors/methods/classes, package representation invariants, package abstract state invariants, HashSet
• How to properly document multi-object abstractions

Advanced topics

(Students of course H02C5A can ignore this material.)

• Iterators
  • Concepts: (external) iterators, iterables, nested classes, inner classes, local classes, anonymous classes, enhanced for loop, internal iterators, lambda expressions, capturing outer variables, effectively final variables
• Streams (on the web)
  • Concepts: streams, sources, map, filter, reduce, collect, parallel streams
• Generics
  • Concepts: generic class, generic interface, type parameter, type argument, generic type instantiation, parameterized type, bounded type parameter, covariance, contravariance, invariance, upper-bounded wildcard, lower-bounded wildcard, generic method, erasure, unchecked cast warning