如何在 BottomNavigationView 中设置选中的项目

Question

我正在尝试为 activity 创建的项目设置默认项，但它不起作用？这是我的代码：

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_userhome);
    mTextMessage = (TextView) findViewById(R.id.message);
    profile = (FrameLayout) findViewById(R.id.profile);
    mall = (FrameLayout) findViewById(R.id.mall);
    dietplan =(FrameLayout) findViewById(R.id.dietplan);
    BottomNavigationView navigation = (BottomNavigationView) 
    findViewById(R.id.navigation);
    navigation.setSelectedItemId(R.id.dietplan);
     navigation.setOnNavigationItemSelectedListener 
    (mOnNavigationItemSelectedListener);
}

但是navigation.setSelectedItemId(R.id.dietplan);好像不行。请帮我设置底部导航栏的默认项：

这是我的堆栈跟踪（logcat）：

FATAL EXCEPTION: main
   Process: gym.android.ommsoftware.gym, PID: 1915
   java.lang.RuntimeException: Unable to start activity ComponentInfo{gym.android.ommsoftware.gym/gym.android.ommsoftware.gym.Userhome}: java.lang.NullPointerException
       at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2404)
       at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2464)
       at android.app.ActivityThread.access0(ActivityThread.java:172)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308)
       at android.os.Handler.dispatchMessage(Handler.java:102)
       at android.os.Looper.loop(Looper.java:146)
       at android.app.ActivityThread.main(ActivityThread.java:5653)
       at java.lang.reflect.Method.invokeNative(Native Method)
       at java.lang.reflect.Method.invoke(Method.java:515)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)
       at dalvik.system.NativeStart.main(Native Method)
    Caused by: java.lang.NullPointerException
       at gym.android.ommsoftware.gym.Userhome.onCreate(Userhome.java:57)
       at android.app.Activity.performCreate(Activity.java:5541)
       at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093)
       at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2368)
       at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2464) 
       at android.app.ActivityThread.access0(ActivityThread.java:172) 
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308) 
       at android.os.Handler.dispatchMessage(Handler.java:102) 
       at android.os.Looper.loop(Looper.java:146) 
       at android.app.ActivityThread.main(ActivityThread.java:5653) 
       at java.lang.reflect.Method.invokeNative(Native Method) 
       at java.lang.reflect.Method.invoke(Method.java:515) 
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291) 
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107) 
       at dalvik.system.NativeStart.main(Native Method)

Answer 1

您需要 setChecked(true) 该项目而不是选择。试试这个代码

mBottomNavigationView=(BottomNavigationView)findViewById(R.id.bottom_nav);
mBottomNavigationView.getMenu().findItem(R.id.item_id).setChecked(true);

选中的项目在 BottomNavigationView 中突出显示。

Answer 2

只是分享我的工作源代码

在Xml、

 <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <android.support.design.widget.BottomNavigationView
        android:background="@color/colorWhite"
        android:id="@+id/gfPrlBnvBtmView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="start"
        android:layout_alignParentBottom="true"
        app:menu="@menu/bottom_navigation_main" />
</LinearLayout>

在Java,

  public class TestActivity extends AppCompatActivity implements BottomNavigationView.OnNavigationItemSelectedListener
{
    private BottomNavigationView mBtmView;
    private int mMenuId;
    @Override
    public void onCreate(@Nullable Bundle savedInstanceState, @Nullable PersistableBundle persistentState) {
        super.onCreate(savedInstanceState, persistentState);
        setContentView(R.layout.test);
        mBtmView = (BottomNavigationView) findViewById(R.id.gfPrlBnvBtmView);
        mBtmView.setOnNavigationItemSelectedListener(this);
        mBtmView.getMenu().findItem(R.id.action_yoga).setChecked(true);
    }

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
        // uncheck the other items.
        mMenuId = item.getItemId();
        for (int i = 0; i < mBtmView.getMenu().size(); i++) {
            MenuItem menuItem = mBtmView.getMenu().getItem(i);
            boolean isChecked = menuItem.getItemId() == item.getItemId();
            menuItem.setChecked(isChecked);
        }

        switch (item.getItemId()) {
            case R.id.action_food: {
            }
            break;
            case R.id.action_medical: {
            }
            break;
            case R.id.action_yoga: {
            }
            break;
            case R.id.action_postures: {
            }
            break;
        }
        return true;
    }
}

Answer 3

这对我有用

Activity布局：

<android.support.design.widget.BottomNavigationView
        android:id="@+id/bottomNavigation"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:itemBackground="@color/colorPrimary"
        app:itemIconTint="@color/tabs"
        app:itemTextColor="@color/tabs"
        app:menu="@menu/bottom_navigation_main" />

color/tabs.xml:

<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <item android:color="@color/not_active" android:state_checked="false"/>
    <item android:color="@color/active" android:state_checked="true"/>

</selector>

点击回调：

@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
    switch (item.getItemId()) {
        case R.id.action_tab0:
            setFragment(f0);
            break;
        case R.id.action_tab1:
            setFragment(f1);
            break;
    }
    return true; // not false!
}

Answer 4

答案的 Kotlin 扩展版本：

internal fun BottomNavigationView.checkItem(actionId: Int) {
    menu.findItem(actionId)?.isChecked = true
}

// use 
bottom_navigation.checkItem(R.id.navigation_home)

这不会触发 OnNavigationItemSelectedListener。

Answer 5

您还可以像这样使用索引在 BottomNavigatioView 中设置选择：

public void selectBottomNavigationOption(int index) {
        switch (index) {
            case 0:
                index = R.id.action_1;
                break;
            case 1:
                index = R.id.action_2;
                break;
            case 2:
                index = R.id.action_3;
                break;
            case 3:
                index = R.id.action_4;
                break;
        }
        bottomNavigationView.setSelectedItemId(index);
    }

Answer 6

将 android:enabled="true" 添加到您的 BottomNavigation 菜单项。

<menu xmlns:android="http://schemas.android.com/apk/res/android">
  <item
    android:id="@+id/menu_id"
    android:enabled="true"
    android:icon="@drawable/ic_my_icon"
    android:title="@string/menu_title"/>
</menu>

并且在onCreate()方法中，设置监听器 bottomNavigationView.setOnNavigationItemSelectedListener(mListener).

并通过 bottomNavigationView.selectedItemId = R.id.menu_id.

设置要选择的项目

这将在创建 activity 时从 NavigationItemSelectedListener 触发 onNavigationItemSelected()。

Answer 7

如果您想要的是被点击的元素在视图中被忽略并且没有被 return 编辑为 "selected" 您可以在处理点击后 return false，在某些情况下案例和一些设计你可能需要打开一个 activity 而不是一个片段，这将在 activity 关闭后选择底部项目。

private val onNavigationItemSelectedListener = BottomNavigationView.OnNavigationItemSelectedListener { item ->
    when (item.itemId) {
        R.id.navigation_shipment -> {
            currentItem = TAB_INDEX_SHIPMENT
            val intent = Intent(this, BookShipmentActivity::class.java)
            startActivity(intent)
            return@OnNavigationItemSelectedListener false
        }
    }
    false
}

Answer 8

您可以使用：

    navigationView?.menu?.findItem(drawableMenuItem.id)?.isChecked = true

它不会触发 OnNavigationItemSelectedListener 事件。

Answer 9

仅供参考：对于片段，onCreateView

BottomNavigationView mBottomNavigationView = getActivity().findViewById(R.id.bottomNavigationView);

mBottomNavigationView.setSelectedItemId(R.id.your_item);

Answer 10

有两个senario

Set the selected menu item ID. This behaves the same as tapping on an item.

代码示例：

BottomNavigationView bottomNavigationView;
bottomNavigationView = (BottomNavigationView) findViewById(R.id.bottomNavigationView);
bottomNavigationView.setOnNavigationItemSelectedListener(myNavigationItemListener);
bottomNavigationView.setSelectedItemId(R.id.my_menu_item_id);

I you only need to check it without tapping

代码示例：

  BottomNavigationView bottomNavigationView= (getActivity()).findViewById(R.id.bottom_navigation);
    bottomNavigationView.getMenu().findItem(R.id.action_manage_orders_id).setChecked(true);

Answer 11

Kotlin 解决方案

在片段中

getActivity()?.myNavigationViewId?.selectedItemId = R.id.other_tab_id

在Activity

myNavigationViewId?.selectedItemId = R.id.other_tab_id

NOTE: Make sure to replace myNavigationViewId and other_tab_id with your actual navigation view and tab ids.

Answer 12

带 Fragment 的 Kotlin 解决方案

var fragment = Fragment()
bottomNav = findViewById(R.id.bottom_nav)
bottomNav.setOnNavigationItemSelectedListener { item ->
  when (item.itemId) {
    R.id.home -> {
      fragment = HomeForm()
    }
    R.id.score -> {
      fragment = ScoreForm()
    }
  }
  supportFragmentManager
    .beginTransaction()
    .replace(R.id.frame_layout, fragment)
    .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN)
    .commit()
  true
}
bottomNav.selectedItemId = R.id.score // init open score tab

Answer 13

对我来说，setSelectedItemId(int id)只显示了片段，但选择的菜单项仍然是错误的。

我发现在 BottomNavigationView 设置完成后调用 setSelectedItemId(int id) 是不够的。

我在 onCreate(savedInstanceState: Bundle?) 中停止调用 setSelectedItemId(int id)，而是在 onResume() 中开始调用它。这解决了问题。

Answer 14

我应该像下面这样，以防您使用导航组件并想要所有控制权。

  private fun setupDashboard() {
    binding.navBottomHome.setOnNavigationItemSelectedListener {
        when (it.itemId) {
            R.id.dashboardFragment -> {
                findNavController(viewId = R.id.dashboardNavGraph).navigate(R.id.dashboardFragment)
                binding.navBottomHome.isSelected = true
            }
            R.id.ordersFragment -> {
                findNavController(viewId = R.id.dashboardNavGraph).navigate(R.id.ordersFragment)
                binding.navBottomHome.isSelected = true
            }
            R.id.productsFragment -> {
                findNavController(viewId = R.id.dashboardNavGraph).navigate(R.id.productsFragment)
                binding.navBottomHome.isSelected = true
            }
            else -> {
                findNavController(viewId = R.id.dashboardNavGraph).navigate(R.id.settingsFragment)
                binding.navBottomHome.isSelected = true
            }
        }
        Log.d("TAG++", "Item selected")
        true
    }
}

简而言之，设置侦听器并设置 binding.navBottomHome.isSelected = true 有效。

如何在 BottomNavigationView 中设置选中的项目

How to Set selected item in BottomNavigationView

android

bottomnavigationview

Kotlin 解决方案