diff --git a/java-strings/src/main/java/com/baeldung/string/Pangram.java b/java-strings/src/main/java/com/baeldung/string/Pangram.java
index 8498a7074a..c09b0c1d29 100644
--- a/java-strings/src/main/java/com/baeldung/string/Pangram.java
+++ b/java-strings/src/main/java/com/baeldung/string/Pangram.java
@@ -15,10 +15,10 @@ public class Pangram {
         Boolean[] alphabetMarker = new Boolean[ALPHABET_COUNT];
         Arrays.fill(alphabetMarker, false);
         int alphabetIndex = 0;
-        str = str.toUpperCase();
+        String strUpper = str.toUpperCase();
         for (int i = 0; i < str.length(); i++) {
-            if ('A' <= str.charAt(i) && str.charAt(i) <= 'Z') {
-                alphabetIndex = str.charAt(i) - 'A';
+            if ('A' <= strUpper.charAt(i) && strUpper.charAt(i) <= 'Z') {
+                alphabetIndex = strUpper.charAt(i) - 'A';
                 alphabetMarker[alphabetIndex] = true;
             }
         }
diff --git a/java-strings/src/test/java/com/baeldung/string/PangramUnitTest.java b/java-strings/src/test/java/com/baeldung/string/PangramUnitTest.java
index 67523a4524..36e603b535 100644
--- a/java-strings/src/test/java/com/baeldung/string/PangramUnitTest.java
+++ b/java-strings/src/test/java/com/baeldung/string/PangramUnitTest.java
@@ -4,39 +4,38 @@ import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 import org.junit.Test;
 
-
 public class PangramUnitTest {
-    
+
     @Test
-    public void givenValidString_isPanagram_shouldReturnSuccess() {
+    public void givenValidString_isPangram_shouldReturnSuccess() {
         String input = "Two driven jocks help fax my big quiz";
-        assertTrue(Pangram.isPangram(input));  
-        assertTrue(Pangram.isPangramWithStreams(input));        
+        assertTrue(Pangram.isPangram(input));
+        assertTrue(Pangram.isPangramWithStreams(input));
     }
-    
+
     @Test
-    public void givenNullString_isPanagram_shouldReturnFailure() {
+    public void givenNullString_isPangram_shouldReturnFailure() {
         String input = null;
         assertFalse(Pangram.isPangram(input));
         assertFalse(Pangram.isPangramWithStreams(input));
         assertFalse(Pangram.isPerfectPangram(input));
     }
-    
+
     @Test
-    public void givenPerfectPanagramString_isPerfectPanagram_shouldReturnSuccess() {
+    public void givenPerfectPangramString_isPerfectPangram_shouldReturnSuccess() {
         String input = "abcdefghijklmNoPqrStuVwxyz";
-        assertTrue(Pangram.isPerfectPangram(input));         
+        assertTrue(Pangram.isPerfectPangram(input));
     }
-    
+
     @Test
-    public void givenNonPanagramString_isPanagram_shouldReturnFailure() {
-        String input = "invalid panagram";
+    public void givenNonPangramString_isPangram_shouldReturnFailure() {
+        String input = "invalid pangram";
         assertFalse(Pangram.isPangram(input));
         assertFalse(Pangram.isPangramWithStreams(input));
     }
-    
+
     @Test
-    public void givenPanagram_isPerfectPanagram_shouldReturnFailure() {
+    public void givenPangram_isPerfectPangram_shouldReturnFailure() {
         String input = "Two driven jocks help fax my big quiz";
         assertFalse(Pangram.isPerfectPangram(input));
     }