[BottomNavigation] Fix hardcoded number of children

lib/java/com/google/android/material/bottomnavigation/BottomNavigationMenuView.java

@@ -42,7 +42,6 @@ public class BottomNavigationMenuView extends NavigationBarMenuView {
   private final int activeItemMinWidth;
 
   private boolean itemHorizontalTranslationEnabled;
-  private int[] tempChildWidths;
 
   public BottomNavigationMenuView(@NonNull Context context) {
     super(context);
@@ -62,8 +61,6 @@ public BottomNavigationMenuView(@NonNull Context context) {
         res.getDimensionPixelSize(R.dimen.design_bottom_navigation_active_item_max_width);
     activeItemMinWidth =
         res.getDimensionPixelSize(R.dimen.design_bottom_navigation_active_item_min_width);
-
-    tempChildWidths = new int[BottomNavigationView.MAX_ITEM_COUNT];
   }
 
   @Override
@@ -74,6 +71,7 @@ protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
     final int visibleCount = menu.getVisibleItems().size();
     // Use total item counts to measure children
     final int totalCount = getChildCount();
+    final int[] tempChildWidths = new int[totalCount];
 
     int parentHeight = MeasureSpec.getSize(heightMeasureSpec);
     final int heightSpec = MeasureSpec.makeMeasureSpec(parentHeight, MeasureSpec.EXACTLY);

lib/java/com/google/android/material/bottomnavigation/BottomNavigationView.java

@@ -88,7 +88,7 @@
  * </pre>
  */
 public class BottomNavigationView extends NavigationBarView {
-  static final int MAX_ITEM_COUNT = 5;
+  private static final int MAX_ITEM_COUNT = 5;
 
   public BottomNavigationView(@NonNull Context context) {
     this(context, null);

lib/javatests/com/google/android/material/bottomnavigation/BottomNavigationMenuViewTest.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.material.bottomnavigation;
+
+import android.content.Context;
+import android.view.Menu;
+
+import androidx.annotation.NonNull;
+import androidx.test.core.app.ApplicationProvider;
+
+import com.google.android.material.test.R;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.internal.DoNotInstrument;
+
+/**
+ * Tests for {@link BottomNavigationMenuView}.
+ */
+@RunWith(RobolectricTestRunner.class)
+@DoNotInstrument
+public final class BottomNavigationMenuViewTest {
+  private static class BottomNavigationViewWithSixMaxItems extends BottomNavigationView {
+    public BottomNavigationViewWithSixMaxItems(@NonNull Context context) {
+      super(context);
+
+      Menu menu = getMenu();
+      menu.add(Menu.NONE, 1, Menu.NONE, "first item");
+      menu.add(Menu.NONE, 2, Menu.NONE, "second item");
+      menu.add(Menu.NONE, 3, Menu.NONE, "third item");
+      menu.add(Menu.NONE, 4, Menu.NONE, "fourth item");
+      menu.add(Menu.NONE, 5, Menu.NONE, "fifth item");
+      menu.add(Menu.NONE, 6, Menu.NONE, "sixth item");
+    }
+
+    @Override
+    public int getMaxItemCount() {
+      return 6;
+    }
+  }
+
+  private final Context context = ApplicationProvider.getApplicationContext();
+
+  @Before
+  public void themeApplicationContext() {
+    context.setTheme(R.style.Theme_MaterialComponents_Light);
+  }
+
+  @Test(expected = Test.None.class /* no exception expected */)
+  public void testOnMeasure_withAnyNumberOfChildren_canMeasure() {
+    BottomNavigationView bottomNavigation = new BottomNavigationViewWithSixMaxItems(context);
+    BottomNavigationMenuView menuView = (BottomNavigationMenuView) bottomNavigation.getMenuView();
+    menuView.measure(0, 0);
+  }
+}
+