如何在 bottomNavigationView android 的项目上显示徽章？

Question

我看到了这个问题 - 并决定将我自己的自定义徽章添加到我的 bottomNavigationView。首先，我为徽章创建了特殊布局：

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/counter_badge"
        android:layout_width="wrap_content"
        android:layout_height="20dp"
        android:layout_gravity="top|center_horizontal"
        android:layout_marginStart="20dp"
        android:gravity="center"
        android:textSize="12sp"
        android:textStyle="bold"
        android:ellipsize="end"
        android:textAlignment="center"
        android:textColor="@color/white"
        android:padding="3dp"
        android:background="@drawable/badge"/>
</FrameLayout>

然后我在我的 activity:

处向徽章 textView 添加一些信息

BottomNavigationMenuView menuView = (BottomNavigationMenuView) bottomNavigationView.getChildAt(0);
BottomNavigationItemView itemView = (BottomNavigationItemView) menuView.getChildAt(0);

notificationBadge = LayoutInflater.from(this).inflate(R.layout.notification_badge, menuView, false);
TextView textView = notificationBadge.findViewById(R.id.counter_badge);

textView.setText("15");

itemView.addView(notificationBadge);

但据我所知，我只能处理视图中的一项，当我尝试从 0 项更改为 1 项时，收到此错误：

java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.support.design.internal.BottomNavigationMenuView.getChildAt(int)' on a null object reference

然后我尝试使用项目的特殊 ID，但我收到类似的错误。也许smb知道如何为我想要的物品添加徽章？

Answer 1

你应该把代码改成这样

BottomNavigationMenuView menuView = (BottomNavigationMenuView) bottomNavigationView.getChildAt(0);
BottomNavigationItemView itemView = (BottomNavigationItemView) menuView.getChildAt(1);

编辑

要让更多项目有徽章，您需要创建另一个布局等等

BottomNavigationMenuView menuView = (BottomNavigationMenuView) bottomNavigationView.getChildAt(0);
BottomNavigationItemView itemView = (BottomNavigationItemView) menuView.getChildAt(0);

notificationBadge = LayoutInflater.from(this).inflate(R.layout.notification_badge, menuView, false);
TextView textView = notificationBadge.findViewById(R.id.counter_badge);
textView.setText("15");
itemView.addView(notificationBadge);

BottomNavigationMenuView menuView1 = (BottomNavigationMenuView) bottomNavigationView.getChildAt(0);
BottomNavigationItemView itemView1 = (BottomNavigationItemView) menuView1.getChildAt(1);

notificationBadgeOne = LayoutInflater.from(this).inflate(R.layout.notification_badge_one, menuView1, false);
TextView textView = notificationBadgeOne.findViewById(R.id.counter_badge);
textView.setText("15");
itemView1.addView(notificationBadgeOne);

Answer 2

只需在 BottomNavigationView 上添加徽章即可：

 private lateinit var bottomNavItemView: BottomNavigationItemView
 private var messageBadgeView: View? = null

 val mBottomNavigationMenuView = getChildAt(0) as BottomNavigationMenuView
 val view = mBottomNavigationMenuView.getChildAt(1)
 bottomNavItemView = view as BottomNavigationItemView

 messageBadgeView = LayoutInflater.from(this@Activity)
          .inflate(R.layout.item_message_count_badge,
                        mBottomNavigationMenuView, false)

 messageBadgeView!!.badgeCount.text = "99+"

 //Add badge
 bottomNavItemView.addView(messageBadgeView)

 //Or Remove badge
 bottomNavItemView.removeView(messageBadgeView)

Answer 3

现在无需自定义视图即可使用

com.google.android.material:material:1.1.0-alpha06

和更新版本

  bottomNavigationView.getOrCreateBadge(R.id.bottom_navigation_view_item).apply {
  backgroundColor = Color.RED
  badgeTextColor = Color.WHITE
  maxCharacterCount = 3
  number = 0
  isVisible = true
}

Answer 4

无法访问 getOrCreaeteBadge 的人的另一种方法是使用以下方法；

确保底部导航的主题设置为： Theme.MaterialComponents.Light.DarkActionBar

然后现在：

 String messages = getIntent().getStringExtra("messages_count");
 messages = messages.substring(10,11);
 Log.d("MessagesCount", "getIncomingIntent: "+messages);
 navigation.showBadge(R.id.bottom_messages).setNumber(Integer.parseInt(messages));

你可以开始了！示例输出如下

如何在 bottomNavigationView android 的项目上显示徽章？

How to display badge on items of bottomNavigationView android?

android

bottomnavigationview