Last modified on 17 Dec 2021

Comp 303 Final Notes

For more notes on design patterns, see here

UML

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

Notation

^{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

Concurrency

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

Serialization

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) {
        this.name = 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)
                out.println(d.serialize());
        }
    }

    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.add(Data.deserialize(line));
        }
        Data[] result = new Data[data.size()];
        data.toArray(result);
        return result;
    }

}