Merge pull request eugenp#8109 from martinvw/feature/BAEL-3392

[BAEL-3392] Debugging Java 8 Streams with IntelliJ

Author: eric-martin

core-java-modules/core-java-streams-3/src/main/java/com/baeldung/streams/debug/entity/Customer.java

@@ -0,0 +1,19 @@
+package com.baeldung.streams.debug.entity;
+
+public class Customer {
+    private final String name;
+    private final int age;
+
+    public Customer(String name, int age) {
+        this.name = name;
+        this.age = age;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public int getAge() {
+        return age;
+    }
+}

core-java-modules/core-java-streams-3/src/test/java/com/baeldung/streams/debug/Example1.java

@@ -0,0 +1,18 @@
+package com.baeldung.streams.debug;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.stream.IntStream;
+
+import org.junit.Test;
+
+public class Example1 {
+    @Test
+    public void whenDebugging_thenInformationIsShown() {
+        int[] listOutputSorted = IntStream.of(-3, 10, -4, 1, 3)
+            .sorted()
+            .toArray();
+
+        assertThat(listOutputSorted).isSorted();
+    }
+}

core-java-modules/core-java-streams-3/src/test/java/com/baeldung/streams/debug/Example2.java

@@ -0,0 +1,36 @@
+package com.baeldung.streams.debug;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Stream;
+
+import org.junit.Test;
+
+import com.baeldung.streams.debug.entity.Customer;
+
+public class Example2 {
+    @Test
+    public void whenDebugging_thenInformationIsShown() {
+        List<Optional<Customer>> customers = Arrays.asList(
+            Optional.of(new Customer("John P.", 15)),
+            Optional.of(new Customer("Sarah M.", 78)),
+            Optional.empty(),
+            Optional.of(new Customer("Mary T.", 20)),
+            Optional.empty(),
+            Optional.of(new Customer("Florian G.", 89)),
+            Optional.empty()
+        );
+
+        long numberOf65PlusCustomers = customers.stream()
+            .flatMap(c -> c.map(Stream::of)
+              .orElseGet(Stream::empty))
+            .mapToInt(Customer::getAge)
+            .filter(c -> c > 65)
+            .count();
+
+        assertThat(numberOf65PlusCustomers).isEqualTo(2);
+    }
+}