Add examples of avoiding forEach methods

aplotnikov · aplotnikov · commit e814570bb293 · 2018-12-26T18:38:12.000+01:00
diff --git a/src/main/java/io/github/aplotnikov/java_8_misuses/stream/AvoidLoopsInStreams.java b/src/main/java/io/github/aplotnikov/java_8_misuses/stream/AvoidLoopsInStreams.java
@@ -0,0 +1,34 @@
+package io.github.aplotnikov.java_8_misuses.stream;
+
+import io.github.aplotnikov.java_8_misuses.domain.Client;
+
+import java.util.List;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import static io.github.aplotnikov.java_8_misuses.utils.Annotations.Good;
+import static io.github.aplotnikov.java_8_misuses.utils.Annotations.Ugly;
+
+class AvoidLoopsInStreams {
+
+    @Ugly
+    class UseExternalCounter {
+        double countAverageLoansPerClient(List<Client> clients) {
+            if (clients.isEmpty()) {
+                return 0;
+            }
+            AtomicInteger totalCount = new AtomicInteger();
+            clients.forEach(client -> totalCount.addAndGet(client.getLoans().size()));
+            return totalCount.doubleValue() / clients.size();
+        }
+    }
+
+    @Good
+    class ApplyMappingsToTargetType {
+        double countAverageLoansPerClient(List<Client> clients) {
+            return clients.stream()
+                          .mapToDouble(client -> client.getLoans().size())
+                          .average()
+                          .orElse(0);
+        }
+    }
+}
