diff --git a/core-java-concurrency/src/main/java/com/baeldung/concurrent/daemon/NewThread.java b/core-java-concurrency/src/main/java/com/baeldung/concurrent/daemon/NewThread.java
new file mode 100644
index 0000000000..6ddcb954a1
--- /dev/null
+++ b/core-java-concurrency/src/main/java/com/baeldung/concurrent/daemon/NewThread.java
@@ -0,0 +1,10 @@
+package com.baeldung.concurrent.daemon;
+
+public class NewThread extends Thread {
+
+    public void run() {
+        while (true)
+            for (int i = 0; i < 10; i++)
+                System.out.println("New Thread is running...");
+    }
+}
diff --git a/core-java-concurrency/src/test/java/com/baeldung/concurrent/daemon/DaemonThreadTest.java b/core-java-concurrency/src/test/java/com/baeldung/concurrent/daemon/DaemonThreadTest.java
new file mode 100644
index 0000000000..2c4eeb63d6
--- /dev/null
+++ b/core-java-concurrency/src/test/java/com/baeldung/concurrent/daemon/DaemonThreadTest.java
@@ -0,0 +1,28 @@
+package com.baeldung.concurrent.daemon;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+public class DaemonThreadTest {
+
+    @Test
+    public void whenCallIsDaemon_thenCorrect() {
+        NewThread daemonThread = new NewThread();
+        NewThread userThread = new NewThread();
+        daemonThread.setDaemon(true);
+        daemonThread.start();
+        userThread.start();
+
+        assertTrue(daemonThread.isDaemon());
+        assertFalse(userThread.isDaemon());
+    }
+
+    @Test(expected = IllegalThreadStateException.class)
+    public void givenUserThread_whenSetDaemonWhileRunning_thenIllegalThreadStateException() {
+        NewThread daemonThread = new NewThread();
+        daemonThread.start();
+        daemonThread.setDaemon(true);
+    }
+}
diff --git a/core-java/src/test/java/com/baeldung/string/StringTest.java b/core-java/src/test/java/com/baeldung/string/StringTest.java
index 0e325950b0..fe1a69aa23 100644
--- a/core-java/src/test/java/com/baeldung/string/StringTest.java
+++ b/core-java/src/test/java/com/baeldung/string/StringTest.java
@@ -5,6 +5,7 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
+import java.io.UnsupportedEncodingException;
 import java.nio.charset.StandardCharsets;
 import java.util.IllegalFormatException;
 import java.util.regex.PatternSyntaxException;
@@ -29,11 +30,17 @@ public class StringTest {
     }
 
     @Test
-    public void whenGetBytes_thenCorrect() {
-        byte[] byteArray = "abcd".getBytes();
-        byte[] expected = new byte[] { 97, 98, 99, 100 };
+    public void whenGetBytes_thenCorrect() throws UnsupportedEncodingException {
+        byte[] byteArray1 = "abcd".getBytes();
+        byte[] byteArray2 = "efgh".getBytes(StandardCharsets.US_ASCII);
+        byte[] byteArray3 = "ijkl".getBytes("UTF-8");
+        byte[] expected1 = new byte[] { 97, 98, 99, 100 };
+        byte[] expected2 = new byte[] { 101, 102, 103, 104 };
+        byte[] expected3 = new byte[] { 105, 106, 107, 108 };
 
-        assertArrayEquals(expected, byteArray);
+        assertArrayEquals(expected1, byteArray1);
+        assertArrayEquals(expected2, byteArray2);
+        assertArrayEquals(expected3, byteArray3);
     }
 
     @Test
@@ -123,6 +130,7 @@ public class StringTest {
     @Test
     public void whenCallLastIndexOf_thenCorrect() {
         assertEquals(2, "foo".lastIndexOf("o"));
+        assertEquals(2, "foo".lastIndexOf(111));
     }
 
     @Test