PROG2 Klausur

Important

Was kommt in der Klausur dran ?

1. MC

2. Recursion / Iterative Approaches

3. Generics / Lambda Expressions / Streams

• Lambda Ausdrücke

• Collections

• C ( relativ wenig) vielleicht was mit Pointers

Funktionen gcc-Compiler

Java Map, Queue, List, Tree → Collections, hauptsächlich Funktionen zum Hinzufügen/Entfernen
stream()
Predicate, Comparator
Sorting algorithms
C Basics

Klausur 2019

Zusatzaufgaben

Übungen in Vorlesungen

03-inner Classes

Collection Type	Implementation	Ordered	Sorted	Allows Duplicates	Null Keys	Null Values
Set	==HashSet==	No	No	No	N/A	Yes
Set	==LinkedHashSet==	Yes	No	No	N/A	Yes
Set	==TreeSet==	No	Yes	No	N/A	No
Map	==HashMap==	No	No	No (keys)	Yes	Yes
Map	==LinkedHashMap==	Yes	No	No (keys)	Yes	Yes
Map	==TreeMap==	No	Yes	No (keys)	No	Yes
Map	Hashtable	No	No	No (keys)	No	No
Map	ConcurrentHashMap	No	No	No (keys)	No	Yes
List	==ArrayList==	Yes	No	Yes	N/A	Yes
List	==LinkedList==	Yes	No	Yes	N/A	Yes
List	Vector	Yes	No	Yes	N/A	Yes
List	Stack	Yes	No	Yes	N/A	Yes

Explanation:

• Ordered: Maintains the order of elements as they are inserted.

• Sorted: Maintains elements in a sorted order based on natural ordering or a specified comparator.

• Allows Duplicates: Whether the collection allows duplicate elements (for Set and List) or duplicate keys (for Map).

• Null Keys: Whether the collection allows null keys (applicable to Map only).

• Null Values: Whether the collection allows null values.

Notes:

• HashSet and HashMap do not maintain any specific order.

• LinkedHashSet and LinkedHashMap maintain the insertion order.

• TreeSet and TreeMap maintain elements in a sorted order.

• Hashtable and ConcurrentHashMap do not allow null keys or values.

• TreeSet does not allow null elements, and TreeMap does not allow null keys but allows null values.

• ArrayList, LinkedList, Vector, and Stack maintain the insertion order and allow duplicates and null values.

Generics

• allows writing flexible,

• type-safe code

• reusable code

• allow types to be parameters when defining classes, interfaces and methods.

Easy Example :

package generics;
 
public class Box<T>{
 
 
    /**
     *
     * Here, Box can store any type T.
     */
    private T item ;
 
    public void setItem(T item ){
        this.item = item;
    }
 
    public <T> void printItem(T item) {
        System.out.println(item);
    }
 
 
}

• Here, printItem( T item ) is a generic method, that means that it is not bound to any type.

we can L

! Collections

Keep in mind :

• when deleting elements while iterating over a Collections it cna get messed up

  • thats why a safe removal is important