Implement addAll with index for CustomArrayList. Fix bug in previous addAll (w/o index)

Author: andrei-punko

src/main/java/by/andd3dfx/collections/custom/CustomArrayList.java

@@ -204,26 +204,46 @@ public boolean addAll(Collection<? extends T> c) {
         }
 
         var incomingArray = c.toArray();
-        if (array.length >= size + c.size()) {
-            System.arraycopy(incomingArray, 0, array, size, c.size());
-        } else {
-            int oldLength = array.length;
-            var newLength = oldLength;
+        if (array.length < size + c.size()) {
+            var newLength = array.length;
             while (newLength < size + c.size()) {
                 newLength *= RESIZE_FACTOR;
             }
             var newArray = (T[]) new Object[newLength];
             System.arraycopy(array, 0, newArray, 0, size);
             array = newArray;
-            System.arraycopy(incomingArray, 0, array, size, c.size());
         }
+        System.arraycopy(incomingArray, 0, array, size, c.size());
+        size += c.size();
+
         return true;
     }
 
     @Override
     public boolean addAll(int index, Collection<? extends T> c) {
-        // TODO add implementation
-        throw new NotImplementedException();
+        if (c.isEmpty()) {
+            return false;
+        }
+
+        var incomingArray = c.toArray();
+        if (array.length < size + c.size()) {
+            var newLength = array.length;
+            while (newLength < size + c.size()) {
+                newLength *= RESIZE_FACTOR;
+            }
+            var newArray = (T[]) new Object[newLength];
+
+            System.arraycopy(array, 0, newArray, 0, index);
+            System.arraycopy(incomingArray, 0, newArray, index, c.size());
+            System.arraycopy(array, index, newArray, index + c.size(), size - index);
+            array = newArray;
+        } else {
+            System.arraycopy(array, index, array, index + c.size(), size - index);
+            System.arraycopy(incomingArray, 0, array, index, c.size());
+        }
+        size += c.size();
+
+        return true;
     }
 
     @Override

src/test/java/by/andd3dfx/collections/custom/CustomArrayListTest.java

@@ -356,36 +356,29 @@ public void testContainsAll() {
     }
 
     @Test
-    public void testAddAllNoResize() {
-        List<String> list = new CustomArrayList<>();
+    public void testAddAll_NoResize() {
+        var list = new CustomArrayList<>();
         list.add("Andrei");
         list.add("Tikhon");
         list.add("Ilya");
 
         list.addAll(List.of("Taisia", "Nika"));
 
-        assertThat(list.contains("Andrei")).isTrue();
-        assertThat(list.contains("Tikhon")).isTrue();
-        assertThat(list.contains("Ilya")).isTrue();
-        assertThat(list.contains("Taisia")).isTrue();
-        assertThat(list.contains("Nika")).isTrue();
+        assertThat(list.size()).isEqualTo(5);
+        assertThat(list.toString()).isEqualTo("[Andrei, Tikhon, Ilya, Taisia, Nika]");
     }
 
     @Test
-    public void testAddAllResizeRequired() {
-        List<String> list = new CustomArrayList<>();
+    public void testAddAll_ResizeRequired() {
+        var list = new CustomArrayList<>();
         list.add("Andrei");
         list.add("Tikhon");
         list.add("Ilya");
 
         list.addAll(List.of("Taisia", "Nika", "Taisia", "Nika", "Taisia", "Alexey", "Taisia", "Nika"));
 
-        assertThat(list.contains("Andrei")).isTrue();
-        assertThat(list.contains("Tikhon")).isTrue();
-        assertThat(list.contains("Ilya")).isTrue();
-        assertThat(list.contains("Taisia")).isTrue();
-        assertThat(list.contains("Nika")).isTrue();
-        assertThat(list.contains("Alexey")).isTrue();
+        assertThat(list.size()).isEqualTo(11);
+        assertThat(list.toString()).isEqualTo("[Andrei, Tikhon, Ilya, Taisia, Nika, Taisia, Nika, Taisia, Alexey, Taisia, Nika]");
     }
 
     @Test
@@ -511,9 +504,28 @@ public void subList() {
     }
 
     @Test
-    public void addAllWithIndex() {
+    public void testAddAllWithIndex_NoResize() {
         var list = new CustomArrayList<>();
+        list.add("Andrei");
+        list.add("Tikhon");
+        list.add("Ilya");
+
+        list.addAll(1, List.of("Taisia", "Nika"));
+
+        assertThat(list.size()).isEqualTo(5);
+        assertThat(list.toString()).isEqualTo("[Andrei, Taisia, Nika, Tikhon, Ilya]");
+    }
+
+    @Test
+    public void testAddAllWithIndex_ResizeRequired() {
+        var list = new CustomArrayList<>();
+        list.add("Andrei");
+        list.add("Tikhon");
+        list.add("Ilya");
+
+        list.addAll(1, List.of("Taisia", "Nika", "Taisia", "Nika", "Taisia", "Alexey", "Taisia", "Nika"));
 
-        assertThrows(NotImplementedException.class, () -> list.addAll(1, List.of(25, 27)));
+        assertThat(list.size()).isEqualTo(11);
+        assertThat(list.toString()).isEqualTo("[Andrei, Taisia, Nika, Taisia, Nika, Taisia, Alexey, Taisia, Nika, Tikhon, Ilya]");
     }
 }