当我使用 FragmentTransaction 的 add() 和 replace() 方法时，我的应用程序崩溃了

Question

每当单击导航抽屉上的项目时，我都想更改片段。 当我使用 add() 和 replace() 方法时，我的应用程序崩溃了。

以下是我的代码。

EventActivity.java：

public class EventActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {

  FragmentTransaction fragmentTransaction;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_event);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    fragmentTransaction = getSupportFragmentManager().beginTransaction();


/** App crashes when I add this Line, but there is no error on the console **/
    fragmentTransaction.add(R.id.main_container, new AboutFragment());
    fragmentTransaction.commit();

    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.setDrawerListener(toggle);
    toggle.syncState();

    NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);

  }

  @Override
  public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    switch(id) {
        case R.id.nav_about:
            //.setVisibility(View.GONE);
            fragmentTransaction = getSupportFragmentManager().beginTransaction();

/** Error here **/
            fragmentTransaction.replace(R.id.main_container, new AboutFragment());
            fragmentTransaction.commit();
            break;
        case R.id.nav_agenda:
            break;
        case R.id.nav_news_feed:
            break;
        case R.id.nav_speakers:
            break;
        case R.id.nav_contact_us:
            break;
        case R.id.nav_chat:
    }
  //End of EventActivity.java

app_bar_event.xml：

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.tedxdsce.tedxdsce.EventActivity">

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:popupTheme="@style/AppTheme.PopupOverlay" />

    </android.support.design.widget.AppBarLayout>
    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/main_container"
        >
    </FrameLayout>

    <include layout="@layout/content_event" />
</LinearLayout>



<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="bottom|end"
    android:layout_margin="@dimen/fab_margin"
    app:srcCompat="@android:drawable/ic_dialog_email" />

层次结构是：

activity_event.xml -> app_bar_event.xml - main_container(FrameLayout) -> content_event.xml

非常感谢您在此问题上的时间和帮助。

编辑：应用程序在日志控制台中没有任何错误就崩溃了。

Answer 1

首先欢迎来到 SO，如果您发布任何问题，那么至少发布错误 用它记录。以便其他开发人员可以直接检测错误。 您也应该重播其他开发人员的评论！ 我在这里看不到

无论如何，像这样设置您的抽屉布局和导航视图。

  public class MainActivity extends AppCompatActivity implements View.OnClickListener ,NavigationView.OnNavigationItemSelectedListener {

                String TAG = "MainActivity";
                DrawerLayout drawer;
                NavigationView navigationView;
                Toolbar toolbar;


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

                    getData();
                    init();
                    setData();
                    setListner();
                }

                private void setListner() {
                }



                private void init() {


                    navigationView = (NavigationView) findViewById(R.id.nav_view);
                    drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
                    toolbar = (Toolbar) findViewById(R.id.toolbar);

                }

                private void setData() {


                    toolbar.setTitle(getResources().getString("title"));
                    setSupportActionBar(toolbar);
                    // getSupportActionBar().setTitle("Home");
                    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
                    drawer.setDrawerListener(toggle);
                    toggle.syncState();

                    //Setting default as first fragment which is at position 0
                    navigationView.getMenu().getItem(0).setChecked(true);
                    onNavigationItemSelected(navigationView.getMenu().getItem(0));
                    //toggle.setDrawerIndicatorEnabled(false);
                    navigationView.setNavigationItemSelectedListener(this);

                }

     @Override
        public void onClick(View v) {

        }


        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) {

            int id = item.getItemId();
            Fragment fragment = null;
            switch (id) {

                case R.id.about_us:
                    toolbar.setTitle(getResources().getString("title of your fragment"));
                    getSupportFragmentManager().popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
                    fragment =  new AboutFragment();
                    break;

          // other fragments as per the navigation items...
            }

            android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
            fragmentTransaction.replace(R.id.fragment_container, fragment);
            fragmentTransaction.commit();
            drawer.closeDrawer(GravityCompat.START);
            return true;
        }

    }

我希望您的 AboutUs 片段是正确的。

Answer 2

试试这个例子：

使用导航抽屉的 Android 滑动菜单

https://www.androidhive.info/2013/11/android-sliding-menu-using-navigation-drawer/

Answer 3

感谢大家的回答。

我已经解决了这个问题。我忘记实现 onFragmentInteracion 接口了。

public class EventActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener,
        AboutFragment.OnFragmentInteractionListener{

FragmentTransaction fragmentTransaction;

PS：我之前想不通，因为我的应用一直在崩溃而没有任何错误日志。