From e959114bc709ed59f445a0c569ca277168bec91b Mon Sep 17 00:00:00 2001
From: "Kai.Yuan" <kent.yuan@Gmail.com>
Date: Sun, 17 Mar 2024 17:27:57 +0100
Subject: [PATCH 1/3] [add-to-immutable-list] wip

---
 .../AddElementsToImmutableListUnitTest.java   | 47 +++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 core-java-modules/core-java-collections-list-6/src/test/java/com/baeldung/addtoimmutablelist/AddElementsToImmutableListUnitTest.java

diff --git a/core-java-modules/core-java-collections-list-6/src/test/java/com/baeldung/addtoimmutablelist/AddElementsToImmutableListUnitTest.java b/core-java-modules/core-java-collections-list-6/src/test/java/com/baeldung/addtoimmutablelist/AddElementsToImmutableListUnitTest.java
new file mode 100644
index 0000000000..f7ad690acb
--- /dev/null
+++ b/core-java-modules/core-java-collections-list-6/src/test/java/com/baeldung/addtoimmutablelist/AddElementsToImmutableListUnitTest.java
@@ -0,0 +1,47 @@
+package com.baeldung.addtoimmutablelist;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+public class AddElementsToImmutableListUnitTest {
+
+    public static <T> List<T> appendAnElement(List<T> immutableList, T element) {
+        List<T> tmpList = new ArrayList<>(immutableList);
+        tmpList.add(element);
+        return List.copyOf(tmpList);
+    }
+
+    public static <T> List<T> appendElements(List<T> immutableList, T... elements) {
+        List<T> tmpList = new ArrayList<>(immutableList);
+        tmpList.addAll(Arrays.asList(elements));
+        return List.copyOf(tmpList);
+    }
+
+    @Test
+    void whenCallingAppendAnElement_thenGetExpectedResult() {
+        List<String> myList = List.of("A", "B", "C", "D", "E");
+        List<String> expected = List.of("A", "B", "C", "D", "E", "F");
+        List<String> result = appendAnElement(myList, "F");
+        assertThat(result).isEqualTo(expected)
+            .isUnmodifiable();
+    }
+
+    @Test
+    void whenCallingAppendElements_thenGetExpectedResult() {
+        List<String> myList = List.of("A", "B", "C", "D", "E");
+        List<String> expected1 = List.of("A", "B", "C", "D", "E", "F");
+        List<String> result1 = appendElements(myList, "F");
+        assertThat(result1).isEqualTo(expected1)
+            .isUnmodifiable();
+
+        List<String> expected2 = List.of("A", "B", "C", "D", "E", "F", "G", "H", "I");
+        List<String> result2 = appendElements(myList, "F", "G", "H", "I");
+        assertThat(result2).isEqualTo(expected2)
+            .isUnmodifiable();
+    }
+}
\ No newline at end of file

From 356624bf222f79648cc4e0a74fca727150c6dc56 Mon Sep 17 00:00:00 2001
From: "Kai.Yuan" <kent.yuan@Gmail.com>
Date: Tue, 19 Mar 2024 23:54:56 +0100
Subject: [PATCH 2/3] [add-to-immutable-list] add elements to immutable list

---
 .../addtoimmutablelist/AddElementsToImmutableListUnitTest.java   | 1 +
 1 file changed, 1 insertion(+)

diff --git a/core-java-modules/core-java-collections-list-6/src/test/java/com/baeldung/addtoimmutablelist/AddElementsToImmutableListUnitTest.java b/core-java-modules/core-java-collections-list-6/src/test/java/com/baeldung/addtoimmutablelist/AddElementsToImmutableListUnitTest.java
index f7ad690acb..13484b6dcb 100644
--- a/core-java-modules/core-java-collections-list-6/src/test/java/com/baeldung/addtoimmutablelist/AddElementsToImmutableListUnitTest.java
+++ b/core-java-modules/core-java-collections-list-6/src/test/java/com/baeldung/addtoimmutablelist/AddElementsToImmutableListUnitTest.java
@@ -16,6 +16,7 @@ public class AddElementsToImmutableListUnitTest {
         return List.copyOf(tmpList);
     }
 
+    @SafeVarargs
     public static <T> List<T> appendElements(List<T> immutableList, T... elements) {
         List<T> tmpList = new ArrayList<>(immutableList);
         tmpList.addAll(Arrays.asList(elements));

From 0242528345012c6300cc4463fe873c033febf077 Mon Sep 17 00:00:00 2001
From: "Kai.Yuan" <kent.yuan@Gmail.com>
Date: Wed, 20 Mar 2024 17:20:04 +0100
Subject: [PATCH 3/3] [add-to-immutable-list] replace list.copyof with
 collections.unmodifiableList

---
 .../AddElementsToImmutableListUnitTest.java                  | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/core-java-modules/core-java-collections-list-6/src/test/java/com/baeldung/addtoimmutablelist/AddElementsToImmutableListUnitTest.java b/core-java-modules/core-java-collections-list-6/src/test/java/com/baeldung/addtoimmutablelist/AddElementsToImmutableListUnitTest.java
index 13484b6dcb..397aca8906 100644
--- a/core-java-modules/core-java-collections-list-6/src/test/java/com/baeldung/addtoimmutablelist/AddElementsToImmutableListUnitTest.java
+++ b/core-java-modules/core-java-collections-list-6/src/test/java/com/baeldung/addtoimmutablelist/AddElementsToImmutableListUnitTest.java
@@ -4,6 +4,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 
 import org.junit.jupiter.api.Test;
@@ -13,14 +14,14 @@ public class AddElementsToImmutableListUnitTest {
     public static <T> List<T> appendAnElement(List<T> immutableList, T element) {
         List<T> tmpList = new ArrayList<>(immutableList);
         tmpList.add(element);
-        return List.copyOf(tmpList);
+        return Collections.unmodifiableList(tmpList);
     }
 
     @SafeVarargs
     public static <T> List<T> appendElements(List<T> immutableList, T... elements) {
         List<T> tmpList = new ArrayList<>(immutableList);
         tmpList.addAll(Arrays.asList(elements));
-        return List.copyOf(tmpList);
+        return Collections.unmodifiableList(tmpList);
     }
 
     @Test