Java

Resource aus Jar lesen

InputReader input = getClass().getResourceAsStream("appl.properties");
BufferedReader reader = new BufferedReader(new InputStreamReader(input));
String line;
while( (line = reader.readLine()) != null)
   doIt(line);

Reguläre Ausdrücke

Pattern rexpr = Pattern.compile("Name: (\\w+)");
Matcher matcher;
while( (line = reader.readLine()) != null){
   if ( (matcher = rexpr.matcher(line)).find()){
      name = matcher.group(1);
   }
}

Casting

Staff staff = null;
if(universityUser instanceof Staff)
  staff = (Staff)universityUser;

Container

Map

Map<String, int> priorities = new HashMap<>();
priorities.put("Bob", 2);
for (String key :priorities.keySet()){
  int value = priorities.get(key);
}
if (! priorities.containsKey("Bob")){
  error("missing Bob");
}

Besonderheiten

• Keine Default-Werte bei Parametern. Mit Overloading kann das simuliert werden.
• Generische Typen:

Map<String, Integer> vehicles = new HashMap<>();

Klassen

public abstract class Widget {
    public enum WidgetType { WT_UNDEF, WT_POINT, WT_POLYLINE, WT_TEXT, WT_IMAGE };
    protected int x;
    protected int y;
    protected String color;
    protected WidgetType type;
    Widget(WidgetType type, int x, int y, String color){
        this.x = x;
        this.y = y;
        this.type = type;
        this.color = color;
    }
    public abstract void draw(Sheet sheet);
}
public class PointWidget extends Widget{
    protected int size;
    PointWidget(int x, int y, String color, int size){
        super(WidgetType.WT_POINT, x, y, color);
        this.size = size;
    }

    @Override
    public void draw(Sheet sheet) {
      // ...
    }
}