android - 无法动态膨胀Fragment

Question

我正在关注this在 Android Studio 中的默认抽屉导航 Activity 中膨胀 fragment 的教程。 编译后，我在 logcat 中收到以下错误:

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mayurn.sidepanel2/com.example.mayurn.sidepanel2.MainActivity}: android.view.InflateException: Binary XML file line #12: Binary XML file line #16: Error inflating class fragment

MainActivity.java

public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {

public static String TAG = "mytag";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);         //set Action bar
    setSupportActionBar(toolbar);


    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);       //Fab snackbar
    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);          //Drawer parameters
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.setDrawerListener(toggle);
    toggle.syncState();                                            //show present view in drawer

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

    displaySelectedFrame(R.id.nav_camera);
}

@Override
public void onBackPressed() {
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        super.onBackPressed();
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {                                 //inflate the setting menu
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {

    displaySelectedFrame(item.getItemId());

    return true;

}

public void displaySelectedFrame(int itemId){

    Fragment f = null;

    switch(itemId){

        case R.id.nav_camera:
            f = new frag_1();
            break;

        case R.id.nav_gallery:
            f = new frag_2();
            break;

        case R.id.nav_manage:
            f = new frag_3();
            break;
    }

    if(f!=null){

        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.replace(R.id.content_fragment , f);
        ft.commit();

    }

DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
}

}

现在重要的部分-->>

我的布局关系是这样的activity_main->(include)->app_bar_main->(include)->content_main->(contain)fragment

以下是文件:

activity_main.xml

<android.support.v4.widget.DrawerLayout 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:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start">

    <include
        layout="@layout/app_bar_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <android.support.design.widget.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_main"
        app:menu="@menu/activity_main_drawer" />

</android.support.v4.widget.DrawerLayout>

app_bar_main.xml

<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"
    android:fitsSystemWindows="true"
    tools:context="com.example.mayurn.sidepanel2.MainActivity">

    <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>

    <include layout="@layout/content_main" />

    <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" />

</android.support.design.widget.CoordinatorLayout>

content_main.xml

<RelativeLayout 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:id="@+id/content_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.example.mayurn.sidepanel2.MainActivity"
    tools:showIn="@layout/app_bar_main">

    <fragment
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/content_fragment"
        />

</RelativeLayout>

现在我认为这个 fragment 标签就是我无法膨胀 fragment 的原因。 预览布局也会出现渲染错误，因为我没有设置 android:name 参数。

但我想在用户单击导航面板中的项目后加载它，因此它没有用。

如果我添加此行 android:name="com.example.mayurn.sidepanel2.frag_1" 应用程序会运行，但我会遇到 fragment 重叠问题，例如 frag_1 位于显着位置，而其他 fragment 与它重叠。

我想动态加载 fragment 而不设置android:name参数。

谢谢您的任何帮助，我们将不胜感激。

Answer 1

使用它代替 fragment 标签。

 <FrameLayout
        android:id="@+id/frame_parent"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />