Question

我是Android开发的新手，我正在尝试使用bottomNavigationView创建一个应用程序。我创建了一个单独的类来为不同的活动设置bottomNavigationView，这样我就不必一次又一次地编写代码。但是，当我在Android设备上启动该应用程序时，无论我单击哪个项目，它都将再次启动“欢迎”活动。这是我的navigationHelperClass

public class BottomNavigationViewHelper {
private static final String TAG = "BottomNavigationViewHel";

public static void setUpNavigationView(BottomNavigationViewEx bottomNavigationViewEx){
    Log.d(TAG, "setUpNavigationView: setting BottomNavigation");
    bottomNavigationViewEx.enableAnimation(false);
    bottomNavigationViewEx.enableItemShiftingMode(false);
    bottomNavigationViewEx.enableShiftingMode(false);
    bottomNavigationViewEx.setTextVisibility(false);

}
public static void enableNavigation(final Context context, final BottomNavigationViewEx viewEx){
    viewEx.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) {
            switch(item.getItemId()){
                case R.id.btnHome:
                    viewEx.setSelectedItemId(R.id.btnHome);
                    Intent intent = new Intent(context, Welcome.class);
                    context.startActivity(intent);
                    break;
                case R.id.btnSearch:
                    Intent intent1 = new Intent(context, Chats.class);
                    context.startActivity(intent1);
                    break;
                case R.id.btnPost:
                    Intent intent2 = new Intent(context, Posts.class);
                    context.startActivity(intent2);
                    break;
                case R.id.btnFavourites:
                    Intent intent3 = new Intent(context, Favourites.class);
                    context.startActivity(intent3);
                    break;
                case R.id.btnProfile:
                    Intent intent4 = new Intent(context, Profile.class);
                    context.startActivity(intent4);
                    break;
            }
            return false;
        }
    });

}
}

这是我的“欢迎”活动，当我单击bottomNavigationView的任何一项时，就会开始。

公共类Welcome扩展AppCompatActivity { 私有上下文mCntext = Welcome.this;

private static final String TAG = "Welcome";
BottomNavigationViewEx bottomNav;

@Override
protected void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_welcome);
    Log.d(TAG, "onCreate: starting");
    setupBottomNavigationView();

    Menu menu = bottomNav.getMenu();
    MenuItem menuItem = menu.getItem(0);
    menuItem.setChecked(true);

private void setupBottomNavigationView(){
    Log.d(TAG, "setupBottomNavigationView: setting bottomnavigationview");
    bottomNav = findViewById(R.id.nav_bottom);
    BottomNavigationViewHelper.setUpNavigationView(bottomNav);
    BottomNavigationViewHelper.enableNavigation(mCntext, bottomNav);
}
}

这是我进行的一项活动，其余活动的代码也相同。这是个人资料活动。

public class Profile extends AppCompatActivity {

private Context mContext = Profile.this;
private static final String TAG = "Search";
BottomNavigationViewEx bottomNav;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_profile);
    setupBottomNavigationView();

}

private void setupBottomNavigationView(){
    Log.d(TAG, "setupBottomNavigationView: setting bottomnavigationview");
    bottomNav = findViewById(R.id.nav_bottom);
    BottomNavigationViewHelper.setUpNavigationView(bottomNav);
    BottomNavigationViewHelper.enableNavigation(mContext, bottomNav);
    Menu menu = bottomNav.getMenu();
    MenuItem menuItem = menu.getItem(4);
    menuItem.setChecked(true);
}
@Override
public void setTitle(CharSequence title) {
}
}

Answer 1

删除以下行：

viewEx.setSelectedItemId(R.id.btnHome);

从case R.id.btnHome:回调下的案例onNavigationItemSelected开始。

Answer 2

请勿在活动中使用底部导航，而应使用片段。创建一个将保留您的片段的父活动，然后在onNavigationItemSelectListener中更改这些片段，在这种情况下，您不必管理底部导航状态和所选项目。您可以在此处查看如何更改片段How to change fragment with the Bottom Navigation Activity?

OnNavigationItemsSelected侦听器一次又一次地启动相同的活动

2 个答案: