Generics

name: portada
class: portada-slide, center, middle

# Generics

.footnote[Joan Puigcerver Ibáñez]

---
layout: true
class: regular-slide
.right[.logo[![logoMislata](/itb/images/logo_mislata.png)]]

---
# Generics

```
List<String> list = new ArrayList<String>();
String value = list.get(3);
```

```
List<Rectangle> list = new ArrayList<Rectangle>();
Rectangle rectangle = list.get(3);
```

---
# Generics - Exemple funcions

- Volem fer un mètode que retorni el tercer element d'una llista
	- La llista pot ser de qualsevol tipus

---
# Generics - Exemple funcions
```
public Integer getThird(List<Integer> list) {   
    return list.get(3);
}
```

```
public String getThird(List<String> list) {   
    return list.get(3);
}
```

---
# Generics - Exemple funcions
- Podem definir un tipus generic

```
public <T> T getThird(List<T> list) {   
    return list.get(3);
}
```

```
Integer thirdInteger = getThird(integerList);
String thirdString = getThird(stringList);
```

---
# Generic - Exemple funcions

```
<T> T max(Collection<T> coll, Comparator<T> comp)
```
---
# Generics - Classes

```
/**
 * @param <T> the type of the value being boxed
 */
public class Box<T> {
    // T stands for "Type"
    private T t;

public void set(T t) { this.t = t; }
    public T get() { return t; }
}
```

```
Box<Integer> box = new Box<>();
box.set(3);
```

---

- https://www.baeldung.com/java-generics