Create lists_filter.md

Author: webserveis

lists_filter.md

@@ -0,0 +1,96 @@
+Filtrar listas
+```java
+  private List<Banner> myCollectionA = new ArrayList<>();
+
+  myCollectionA.add(new Banner("r01", "www.google.com", "en"));
+  myCollectionA.add(new Banner("r01", "www.google.com", "es"));
+  myCollectionA.add(new Banner("r02", "caminos de ronda", "es"));
+  myCollectionA.add(new Banner("r03", "descubrir osona", "es"));
+  myCollectionA.add(new Banner("r03", "Osona discover", "en"));
+  myCollectionA.add(new Banner("r03", "Descobirr osona", "ca"));
+  myCollectionA.add(new Banner("r02", "Camins de ronda", "ca"));
+  myCollectionA.add(new Banner("r04", "Ruta del ferro", "ca"));
+```
+
+Filtrar por idioma
+
+```java
+  final List<Banner> myCollectionB = (List<Banner>) CustomPredicate.filter(myCollectionA,
+          new CustomPredicate.IPredicate<Banner>() {
+              public boolean apply(Banner objectOfA) {
+                  return objectOfA.getLang().equals("es");
+              }
+          });
+
+  final List<Banner> myCollectionC = (List<Banner>) CustomPredicate.filter(myCollectionA,
+          new CustomPredicate.IPredicate<Banner>() {
+              public boolean apply(Banner objectOfA) {
+                  return objectOfA.getLang().equals("ca");
+              }
+          });
+
+```
+Obtener diferencias entre listas
+
+```java
+  List<Banner> missingObjects = (List<Banner>) CustomPredicate.filter(myCollectionB,
+          new CustomPredicate.IPredicate<Banner>() {
+              public boolean apply(Banner objectOfA) {
+                  CustomPredicate.predicateParams = objectOfA.getRef();
+                  return CustomPredicate.select(myCollectionC, new CustomPredicate.IPredicate<Banner>() {
+                      public boolean apply(Banner objectOfB) {
+                          return objectOfB.getRef().equals(CustomPredicate.predicateParams.toString());
+                      }
+                  }) == null;
+              }
+          });
+```
+
+
+CustomPredicate.java
+
+```java
+package com.webserveis.app.testlist;
+
+import java.util.ArrayList;
+import java.util.Collection;
+
+public class CustomPredicate<B> {
+    public static Object predicateParams;
+
+    public interface IPredicate<T> { boolean apply(T type); }
+
+    public static <T> Collection<T> filter(Collection<T> target, IPredicate<T> predicate) {
+        Collection<T> result = new ArrayList<T>();
+        for (T element : target) {
+            if (predicate.apply(element)) {
+                result.add(element);
+            }
+        }
+        return result;
+    }
+
+    public static <T> T select(Collection<T> target, IPredicate<T> predicate) {
+        T result = null;
+        for (T element : target) {
+            if (!predicate.apply(element))
+                continue;
+            result = element;
+            break;
+        }
+        return result;
+    }
+
+    public static <T> T select(Collection<T> target, IPredicate<T> predicate, T defaultValue) {
+        T result = defaultValue;
+        for (T element : target) {
+            if (!predicate.apply(element))
+                continue;
+            result = element;
+            break;
+        }
+        return result;
+    }
+}
+```
+