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Last modified on 18 Apr 2019

Comp 303 Final Notes

For more notes on design patterns, see here


Unified Modeling Language

Object Diagram

For class instances

  • Cards are labelled with name:type
  • Values may be primitives or references pointing to other cards

Class Diagram

For static, compile-time view


Taken from prmr/SoftwareDesign

Label Basic Meaning
Generalization extend
Realization implements
Dependency change in one will change another
Association general relationship (eg fields); bi-directional if no arrow drawn
Aggregation “has a/many” associative relationship
Composition physical aggregation (typically, item in composition cannot exist without parent class)

Note that:

  • Diamond is on the side of the container for aggregation/composition
  • Aggregation/composition should indicate cardinality (eg 2, 0..52, etc)
  • Elements represented through arrows should not be duplicated within the cards

State Diagram

For dynamic, run-time view

  • Start denoted by black dot
  • End denoted by black dot with circle
  • States represented by cards
  • Arrows denote transitions
    • Annotated as name[condition] | action (only name is mandatory)
  • Lack of transition means that it is invalid


try {
    lock.lock(); //Reentrant Lock
    // do stuff
} catch (InterruptedException e) {
    // handle stuff
    return; // finally will still be called
} finally {


public class Data {

    private String name;
    private int count;
    private String value;

     * @param name  must not have a space
     * @param count
     * @param value must not have a space
    public Data(String name, int count, String value) { = name;
        this.count = count;
        this.value = value;

    public static Data deserialize(String data) {
        if (data.charAt(0) != '"' || data.charAt(data.length() - 1) != '"')
            throw new IllegalArgumentException("data not in serialized form");
        String[] parts = data.substring(1, data.length() - 1).split(" ");
        return new Data(parts[0], Integer.parseInt(parts[1]), parts[2]);

    public String serialize() {
        return String.format("\"%s %d %s\"", name, count, value);

    public static void write(String path, Data... data) throws IOException {
        try (PrintWriter out = new PrintWriter(new FileWriter(path))) {
            for (Data d : data)

    public static Data[] read(String path) throws IOException {
        List<Data> data = new ArrayList<>();
        try (BufferedReader in = new BufferedReader(new FileReader(path))) {
            for (String line = in.readLine(); line != null; line = in.readLine())
        Data[] result = new Data[data.size()];
        return result;