add examples in java 8 (#12)

* code for chapters 3-9 in Java

* code for chapters 1 in Java

* code for chapter 2 in Java

* missing CheckVoter for chapter 5 in Java

* add missing sample output for SetCovering as a comment

06_breadth-first_search/java/01_breadth_first_search/src/BreadthFirstSearch.java

@@ -0,0 +1,44 @@
+import java.util.*;
+
+public class BreadthFirstSearch {
+    private static Map<String, List<String>> graph = new HashMap<>();
+
+    private static boolean search(String name) {
+        Queue<String> searchQueue = new ArrayDeque<>(graph.get(name));
+        // This list is how you keep track of which people you've searched before.
+        List<String> searched = new ArrayList<>();
+
+        while (!searchQueue.isEmpty()) {
+            String person = searchQueue.poll();
+            // Only search this person if you haven't already searched them
+            if (!searched.contains(person)) {
+                if (person_is_seller(person)) {
+                    System.out.println(person + " is a mango seller!");
+                } else {
+                    searchQueue.addAll(graph.get(person));
+                    // Marks this person as searched
+                    searched.add(person);
+                }
+            }
+        }
+
+        return false;
+    }
+
+    private static boolean person_is_seller(String name) {
+        return name.endsWith("m");
+    }
+
+    public static void main(String[] args) {
+        graph.put("you", Arrays.asList("alice", "bob", "claire"));
+        graph.put("bob", Arrays.asList("anuj", "peggy"));
+        graph.put("alice", Arrays.asList("peggy"));
+        graph.put("claire", Arrays.asList("thom", "jonny"));
+        graph.put("anuj", Collections.emptyList());
+        graph.put("peggy", Collections.emptyList());
+        graph.put("thom", Collections.emptyList());
+        graph.put("jonny", Collections.emptyList());
+
+        search("you");
+    }
+}