diff --git a/lesson_11/arrays_java/arrays_app/src/lib/src/main/kotlin/org/example/Library.kt b/lesson_11/arrays_java/arrays_app/src/lib/src/main/kotlin/org/example/Library.kt
new file mode 100644
index 000000000..9fd8a7f56
--- /dev/null
+++ b/lesson_11/arrays_java/arrays_app/src/lib/src/main/kotlin/org/example/Library.kt
@@ -0,0 +1,10 @@
+/*
+ * This source file was generated by the Gradle 'init' task
+ */
+package org.example
+
+class Library {
+    fun someLibraryMethod(): Boolean {
+        return true
+    }
+}
diff --git a/lesson_11/arrays_java/arrays_app/src/main/java/com/codedifferently/lesson11/Lesson11.java b/lesson_11/arrays_java/arrays_app/src/main/java/com/codedifferently/lesson11/Lesson11.java
index 248938a96..1d9c77890 100644
--- a/lesson_11/arrays_java/arrays_app/src/main/java/com/codedifferently/lesson11/Lesson11.java
+++ b/lesson_11/arrays_java/arrays_app/src/main/java/com/codedifferently/lesson11/Lesson11.java
@@ -1,5 +1,6 @@
 package com.codedifferently.lesson11;
 
+import java.util.ArrayList;
 import java.util.List;
 
 public class Lesson11 {
@@ -12,11 +13,39 @@ public int[] getConcatenation(int[] nums) {
     return null;
   }
 
+  class Solution {
+    public int[] getConcatenation(int[] nums) {
+      int answer[] = new int[2 * nums.length];
+      for (int i = 0; i < nums.length; i++) {
+        answer[i] = nums[i];
+      }
+      int index = nums.length;
+      for (int i = 0; i < nums.length; i++) {
+        answer[index] = nums[i];
+        index++;
+      }
+      return answer;
+    }
+  }
+
   /**
    * Provide the solution to LeetCode 2942 here:
    * https://leetcode.com/problems/find-words-containing-character/
    */
   public List<Integer> findWordsContaining(String[] words, char x) {
+
     return null;
   }
 }
+
+class Solution {
+  public List<Integer> findWordsContaining(String[] words, char x) {
+    List<Integer> resultWords = new ArrayList<>();
+    for (int i = 0; i < words.length; i++) {
+      if (words[i].indexOf(x) != -1) {
+        resultWords.add(i);
+      }
+    }
+    return resultWords;
+  }
+}