Question

因此，当我点击任何项目时，BottomNavigationView会打开一个片段。但最终得到以下错误经度：

 java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.GapWorker.remove(android.support.v7.widget.RecyclerView) on a null object reference
at android.support.v7.widget.RecyclerView.onDetachedFromWindow(RecyclerView.java:2534)
at android.view.View.dispatchDetachedFromWindow(View.java:14392)
at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:3108)
at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:3105)
at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:3105)
at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:3105)
at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:3105)
at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:3105)
at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:3105)
at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:3105)
at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:3105)
at android.view.ViewGroup.removeViewInternal(ViewGroup.java:4472)
at android.view.ViewGroup.removeViewInternal(ViewGroup.java:4445)
at android.view.ViewGroup.removeView(ViewGroup.java:4377)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1411)at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1528)
at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:753)
at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2363)
at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2149)
at android.support.v4.app.FragmentManagerImpl.optimizeAndExecuteOps(FragmentManager.java:2103)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2013)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:710)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:5835)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)

片段

 public class ProfileFragment extends Fragment {



    public ProfileFragment() {
        // Required empty public constructor
    }

    /**
     * Use this factory method to create a new instance of
     * this fragment using the provided parameters.
     *
     * @param param1 Parameter 1.
     * @param param2 Parameter 2.
     * @return A new instance of fragment ProfileFragment.
     */
    // TODO: Rename and change types and number of parameters
    public static ProfileFragment newInstance(String param1, String param2) {
        ProfileFragment fragment = new ProfileFragment();
        Bundle args = new Bundle();
        args.putString(ARG_PARAM1, param1);
        args.putString(ARG_PARAM2, param2);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
            mParam2 = getArguments().getString(ARG_PARAM2);
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.fragment_profile, container, false);

        return view;
    }

切换完成如下：

    runOnUiThread(new Runnable() {
     @Override
     public void run() {
         FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
         transaction.replace(R.id.main_container_home, currFragment,currTag);
         transaction.commit();

      }
 });

任何帮助都会有所帮助

解决方案：

1.空白片段布局并仅使用空子设置相对布局。仍然错误。

应用程序在片段的onCreateView（）崩溃。

UpDate：最终得到崩溃的根本原因是因为我在容器中添加了视图，即container.add（view）

Answer 1

这不是在片段之间切换的方法。你必须将NavigationBottomMenu放在Activity中，创建与BottomNav中的项目数一样多的片段，然后从那里提交片段。

这是 MainActivity.java

t2.start();
t2.join();
t1.start();

}

这是 activity_main.xml

public class MainActivity extends AppCompatActivity{

private BottomNavigationView bottomNavigationView;
private SearchPropertyFragment searchPropertyFragment;
private ChatFragment chatFragment;
private ProfileFragment profileFragment;
private NotificationFragment notificationFragment;

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

    searchPropertyFragment = new SearchPropertyFragment();
    chatFragment = new ChatFragment();
    profileFragment = new ProfileFragment();
    notificationFragment = new NotificationFragment();

    getSupportFragmentManager().beginTransaction().add(R.id.fragment_frame, searchPropertyFragment).commit();

    bottomNavigationView = (BottomNavigationMenu) findViewById(R.id.bottom_navigation);

    bottomNavigationView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) {
            int id = item.getItemId();
            switch (id){
                case R.id.bottom_menu_properties:
                    getSupportFragmentManager().beginTransaction().replace(R.id.fragment_frame, searchPropertyFragment).commit();
                    break;
                case R.id.bottom_menu_chat:
                    getSupportFragmentManager().beginTransaction().replace(R.id.fragment_frame, chatFragment).commit();
                    break;
                case R.id.bottom_menu_profile:
                    getSupportFragmentManager().beginTransaction().replace(R.id.fragment_frame, profileFragment).commit();
                    break;
                case R.id.bottom_menu_notifications:
                    getSupportFragmentManager().beginTransaction().replace(R.id.fragment_frame, notificationFragment).commit();
                    break;
            }
            return true;
        }
    });
}

相应地定义你的片段。

希望这有助于。

切换片段时出错

1 个答案: