Overview and Preliminaries

Why Software Design (Java)?   

Java is an ideal object-oriented language(?)

• Java is a "pure" object-oriented language (almost)
• "simple, dynamic, and secure.."
• pretty cool: web-oriented, portable, concurrent, etc.

• many non-trivial features: classes and polymorphism combined with procedural mechanisms (primitive types, static properties, inner (static/anonymous) classes, exceptions)
• huge class libraries
• in API 1.0: 212 classes and 2125 methods, in Standard Edition (SE) API 1.4, 3020 classes and 32138 methods
• most of Java is in its libraries; you need to know and understand Java class libraries to really do something useful in Java

• how to write reusable and robust code, use and build frameworks and components?
• need to master general object-oriented design patterns to understand existing class libraries and to write new ones
  • Iterator, Composite, Strategy, Observer, Proxy, Template Method, Bridge, etc.

• master language-specific idioms and antipatterns
  • idioms for compareTo, equals, hashCode, toString, clone, type-safe enum classes, exception chaining, etc.
  • antipatterns such as unsynchronized concurrent access, busy-wait, failing double-check idiom, int enum values, using null for zero-length arrays, etc.

• Java language features are in principle "secure" (type-safe)
• but Java programs are not necessarily safe:
  
  • run-time errors and exceptions: how to prevent and/or handle?
  • built-in error detection works only for language features (index check)
  • how to detect higher-level data corruption and invariant violations?
  • how to recover from failures and errors?

• techniques and tools
  • defensive programming and programming-by-contract
  • pre- and post-conditions
  • assert facility
  • to inspect and find out about program you must make its behaviour visible and observable:
    must use debugging and logging
• some aspects of Java are not even in principle portable:
  - nondeterministic threads: scheduling, deadlocks/starvation, etc.
  - also: non-strict (machine-dependent) floating-point calculations

Contents of the Course:

• practical programming techniques concerning:
  - error handling, exceptions, invariants, testing, etc.
  
• overview GUI programming:
  - basic concepts of graphical interfaces in Java
  - event mechanisms and event-driven programming
• software frameworks with samples in Java:
  - general principles
  - design patterns used in object-oriented software
  - Collection and Swing frameworks
• concurrent object-oriented programming:
  - general principles
  - threads, synchronization, thread communication
  - deadlock prevention, etc.
• components and application development:
  - JavaBeans and visual application development

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