From bb4a3b1ac918a88812fdca8c615288e0b2209a2d Mon Sep 17 00:00:00 2001
From: elefus <elefus@yandex.ru>
Date: Thu, 11 Oct 2018 13:06:39 +0300
Subject: [PATCH 1/2] Homework streams.part2.exercise3

---
 .../streams/part2/exercise/Exercise3.java     | 28 +++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 src/test/java/streams/part2/exercise/Exercise3.java

diff --git a/src/test/java/streams/part2/exercise/Exercise3.java b/src/test/java/streams/part2/exercise/Exercise3.java
new file mode 100644
index 0000000..8bd4b80
--- /dev/null
+++ b/src/test/java/streams/part2/exercise/Exercise3.java
@@ -0,0 +1,28 @@
+package streams.part2.exercise;
+
+import org.junit.jupiter.api.Test;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+
+@SuppressWarnings({"unused", "ConstantConditions"})
+class Exercise3 {
+
+    @Test
+    void createLimitedStringWithOddNumbersSeparatedBySpaces() {
+        int countNumbers = 10;
+
+        String result = null;
+
+        assertThat(result, is("1 3 5 7 9 11 13 15 17 19"));
+    }
+
+    @Test
+    void extractEvenNumberedCharactersToNewString() {
+        String source = "abcdefghijklm";
+
+        String result = null;
+
+        assertThat(result, is("acegikm"));
+    }
+}

From 22fa4de415a5e7857308e0272bbe9574bc3fced7 Mon Sep 17 00:00:00 2001
From: Konstantin Romanov <konstantin_romanov@epam.com>
Date: Thu, 25 Oct 2018 12:30:28 +0300
Subject: [PATCH 2/2] Streams part 2 exercise 3 has done

---
 .../streams/part2/exercise/Exercise3.java     | 66 ++++++++++++++++++-
 1 file changed, 64 insertions(+), 2 deletions(-)

diff --git a/src/test/java/streams/part2/exercise/Exercise3.java b/src/test/java/streams/part2/exercise/Exercise3.java
index 8bd4b80..2871a68 100644
--- a/src/test/java/streams/part2/exercise/Exercise3.java
+++ b/src/test/java/streams/part2/exercise/Exercise3.java
@@ -2,6 +2,17 @@
 
 import org.junit.jupiter.api.Test;
 
+import java.util.HashSet;
+import java.util.Set;
+import java.util.function.BiConsumer;
+import java.util.function.BinaryOperator;
+import java.util.function.Function;
+import java.util.function.Predicate;
+import java.util.function.Supplier;
+import java.util.stream.Collector;
+import java.util.stream.Stream;
+
+import static java.util.stream.Collectors.joining;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.is;
 
@@ -12,7 +23,11 @@ class Exercise3 {
     void createLimitedStringWithOddNumbersSeparatedBySpaces() {
         int countNumbers = 10;
 
-        String result = null;
+        String result = Stream.iterate(1, i -> i + 1)
+                .filter(isOddNumber())
+                .limit(countNumbers)
+                .map(String::valueOf)
+                .collect(joining(" "));
 
         assertThat(result, is("1 3 5 7 9 11 13 15 17 19"));
     }
@@ -21,8 +36,55 @@ void createLimitedStringWithOddNumbersSeparatedBySpaces() {
     void extractEvenNumberedCharactersToNewString() {
         String source = "abcdefghijklm";
 
-        String result = null;
+        String result = Stream.iterate(0, i -> i + 1)
+                .limit(source.length())
+                .filter(isEvenNumber())
+                .map(source::charAt)
+                .collect(new CharJoining());
 
         assertThat(result, is("acegikm"));
     }
+
+    private static class CharJoining implements Collector<Character, StringBuffer, String> {
+
+        private HashSet<Characteristics> characteristics;
+
+        public CharJoining() {
+            characteristics = new HashSet<>();
+            characteristics.add(Characteristics.CONCURRENT);
+        }
+
+        @Override
+        public Supplier<StringBuffer> supplier() {
+            return StringBuffer::new;
+        }
+
+        @Override
+        public BiConsumer<StringBuffer, Character> accumulator() {
+            return StringBuffer::append;
+        }
+
+        @Override
+        public BinaryOperator<StringBuffer> combiner() {
+            return StringBuffer::append;
+        }
+
+        @Override
+        public Function<StringBuffer, String> finisher() {
+            return StringBuffer::toString;
+        }
+
+        @Override
+        public Set<Characteristics> characteristics() {
+            return characteristics;
+        }
+    }
+
+    private static Predicate<Integer> isOddNumber() {
+        return n -> n % 2 == 1;
+    }
+
+    private static Predicate<Integer> isEvenNumber() {
+        return n -> n % 2 == 0;
+    }
 }