[Divider] Added attribute in MaterialDividerItemDecoration to remove …

…item decoration from last recycler view item.

PiperOrigin-RevId: 416890397

docs/components/Divider.md

@@ -83,7 +83,7 @@ to a `DividerItemDecoration`, that can be used as a divider between items of a
 
 A list with full-bleed dividers is displayed below:
 
-![Vertical list of five items with gray dividers between each item](assets/dividers/divider_itemdecoration.png)
+![Vertical list of five items with five gray dividers after each item](assets/dividers/divider_itemdecoration.png)
 
 In code:
 
@@ -95,7 +95,7 @@ recyclerView.addItemDecoration(divider)
 By default, dividers will be full-bleed. To achieve the look of an inset or
 middle divider:
 
-![Vertical list of five items with gray dividers that have a start inset](assets/dividers/divider_itemdecoration_inset.png)
+![Vertical list of five items with five gray dividers that have a start inset](assets/dividers/divider_itemdecoration_inset.png)
 
 In code:
 
@@ -104,6 +104,16 @@ divider.setDividerInsetStart(insetStart)
 divider.setDividerInsetEnd(insetEnd)
 ```
 
+Optionally, you can hide the last divider of a list:
+
+![Vertical list of five items with four gray dividers](assets/dividers/divider_itemdecoration_hiddendivider.png)
+
+In code:
+
+```kt
+divider.setLastItemDecorated(false)
+```
+
 ### Making dividers accessible
 
 The divider is a decorative element. There are no special accessibility
@@ -113,12 +123,13 @@ precautions for the divider.
 
 ### Dividers attributes
 
-Element         | Attribute               | Related method(s)                                                                    | Default value
---------------- | ----------------------- | ------------------------------------------------------------------------------------ | -------------
-**Thickness**   | `app:dividerThickness`  | `setDividerThickness`<br/>`setDividerThicknessResource`<br/>`getDividerThickness`    | `1dp` for the regular divider <br/> `8dp` for the heavy divider
-**Color**       | `app:dividerColor`      | `setDividerColor`<br/>`setDividerColorResource`<br/>`getDividerColor`                | `colorOutline`
-**Start inset** | `app:dividerInsetStart` | `setDividerInsetStart`<br/>`setDividerInsetStartResource`<br/>`getDividerInsetStart` | `0dp`
-**End inset**   | `app:dividerInsetEnd`   | `setDividerInsetEnd`<br/>`setDividerInsetEndResource`<br/>`getDividerInsetEnd`       | `0dp`
+Element                 | Attribute               | Related method(s)                                                                    | Default value
+----------------------- | ----------------------  | ------------------------------------------------------------------------------------ | -------------
+**Thickness**           | `app:dividerThickness`  | `setDividerThickness`<br/>`setDividerThicknessResource`<br/>`getDividerThickness`    | `1dp` for the regular divider <br/> `8dp` for the heavy divider
+**Color**               | `app:dividerColor`      | `setDividerColor`<br/>`setDividerColorResource`<br/>`getDividerColor`                | `colorOutline`
+**Start inset**         | `app:dividerInsetStart` | `setDividerInsetStart`<br/>`setDividerInsetStartResource`<br/>`getDividerInsetStart` | `0dp`
+**End inset**           | `app:dividerInsetEnd`   | `setDividerInsetEnd`<br/>`setDividerInsetEndResource`<br/>`getDividerInsetEnd`       | `0dp`
+**Last item decorated** | `app:lastItemDecorated` | `setLastItemDecorated`<br/>`isLastItemDecorated`                                     | `true`
 
 ### Styles
 

lib/java/com/google/android/material/divider/MaterialDividerItemDecoration.java

@@ -66,6 +66,7 @@ public class MaterialDividerItemDecoration extends ItemDecoration {
   private int orientation;
   private int insetStart;
   private int insetEnd;
+  private boolean lastItemDecorated;
 
   private final Rect tempRect = new Rect();
 
@@ -95,6 +96,8 @@ public MaterialDividerItemDecoration(
     insetStart =
         attributes.getDimensionPixelOffset(R.styleable.MaterialDivider_dividerInsetStart, 0);
     insetEnd = attributes.getDimensionPixelOffset(R.styleable.MaterialDivider_dividerInsetEnd, 0);
+    lastItemDecorated =
+        attributes.getBoolean(R.styleable.MaterialDivider_lastItemDecorated, true);
 
     attributes.recycle();
 
@@ -259,6 +262,27 @@ public int getDividerInsetEnd() {
     return insetEnd;
   }
 
+  /**
+   * Sets whether the class should draw a divider after the last item of a {@link RecyclerView}.
+   *
+   * @param lastItemDecorated whether there's a divider after the last item of a recycler view.
+   * @see #isLastItemDecorated()
+   * @attr ref com.google.android.material.R.styleable#MaterialDivider_lastItemDecorated
+   */
+  public void setLastItemDecorated(boolean lastItemDecorated) {
+    this.lastItemDecorated = lastItemDecorated;
+  }
+
+  /**
+   * Whether there's a divider after the last item of a {@link RecyclerView}.
+   *
+   * @see #setLastItemDecorated(boolean)
+   * @attr ref com.google.android.material.R.styleable#MaterialDivider_shouldDecorateLastItem
+   */
+  public boolean isLastItemDecorated() {
+    return lastItemDecorated;
+  }
+
   @Override
   public void onDraw(
       @NonNull Canvas canvas, @NonNull RecyclerView parent, @NonNull RecyclerView.State state) {
@@ -294,7 +318,8 @@ private void drawForVerticalOrientation(@NonNull Canvas canvas, @NonNull Recycle
     right -= isRtl ? insetStart : insetEnd;
 
     int childCount = parent.getChildCount();
-    for (int i = 0; i < childCount; i++) {
+    int dividerCount = lastItemDecorated ? childCount : childCount - 1;
+    for (int i = 0; i < dividerCount; i++) {
       View child = parent.getChildAt(i);
       parent.getDecoratedBoundsWithMargins(child, tempRect);
       // Take into consideration any translationY added to the view.

lib/java/com/google/android/material/divider/res-public/values/public.xml

@@ -20,6 +20,7 @@
   <public name="dividerThickness" type="attr"/>
   <public name="dividerInsetStart" type="attr"/>
   <public name="dividerInsetEnd" type="attr"/>
+  <public name="lastItemDecorated" type="attr"/>
   <public name="Widget.MaterialComponents.MaterialDivider" type="style"/>
   <public name="Widget.Material3.MaterialDivider" type="style"/>
   <public name="Widget.Material3.MaterialDivider.Heavy" type="style"/>

lib/java/com/google/android/material/divider/res/values/attrs.xml

@@ -33,5 +33,8 @@
     <attr name="dividerInsetEnd"/>
     <!-- End indent of the divider. -->
     <attr name="dividerInsetStart"/>
+    <!-- Whether the MaterialDividerItemDecoration class should draw a divider
+         after the last item of the recycler view. True by default. -->
+    <attr name="lastItemDecorated" format="boolean"/>
   </declare-styleable>
 </resources>

lib/javatests/com/google/android/material/divider/MaterialDividerItemDecorationTest.java

@@ -127,6 +127,18 @@ public void setDividerInsetEndResource_succeeds() {
     assertThat(divider.getDividerInsetEnd()).isEqualTo(2);
   }
 
+  @Test
+  public void isLastItemDecorated_isTrueByDefault() {
+    assertThat(divider.isLastItemDecorated()).isTrue();
+  }
+
+  @Test
+  public void setLastItemNotDecorated_succeeds() {
+    divider.setLastItemDecorated(false);
+
+    assertThat(divider.isLastItemDecorated()).isFalse();
+  }
+
   @Test
   public void getItemOffsets_verticalOrientation_returnsCorrectRect() {
     divider.getItemOffsets(rect, /* view= */ null, recyclerView, state);