java - findViewById 在 Fragment 中找不到 ImageButton

Question

我正在尝试在我正在创建的信息应用程序的一个片段中流式传输视频。当我创建图像按钮来控制视频时，findViewById在线上出现“无法解析符号”错误btnPlayPause = (ImageButton)findViewById(R.id.play_pause_button);，但是它可以在同一片段中找到视频视图。这是我的onCreate方法MainActivity.java：

public class MainActivity extends AppCompatActivity implements 
NavigationView.OnNavigationItemSelectedListener{
private DrawerLayout drawer;
ProgressDialog mDialog;
VideoView videoView;
ImageButton btnPlayPause;

String videoURL = "https://vimeo.com/284762179";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);

    Toolbar toolbar = findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

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

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

    if (savedInstanceState == null { getSupportFragmentManager() 
.beginTransaction().replace(R.id.fragment_containter,
                new InformationFragment()).commit();
        navigationView.setCheckedItem(R.id.nav_information);
    }

    videoView = (VideoView)findViewById(R.id.hypori_video);
    btnPlayPause = (ImageButton)findViewById(R.id.play_pause_button);
    btnPlayPause.setOnClickListener(this);
 }

 @Override
 public void onClick(View v){
    mDialog = new ProgressDialog(MainActivity.this);
    mDialog.setMessage("Please wait...");
    mDialog.setCanceledOnTouchOutside(false);
    mDialog.show();

    try {
        if (!videoView.isPlaying()) {
            Uri uri = Uri.parse(videoURL);
            videoView.setVideoURI(uri);
            videoView.setOnCompletionListener(new 
     MediaPlayer.OnCompletionListener() {
                @Override
                public void onCompletion(MediaPlayer mp) {
                    btnPlayPause.setImageResource(R.drawable.ic_play_arrow);
                }
            });
        }
        else
        {
            videoView.pause();
            btnPlayPause.setImageResource(R.drawable.ic_play_arrow);
        }
    }
    catch (Exception e)
    {

    }
    videoView.requestFocus();
    videoView.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
        @Override
        public void onPrepared(MediaPlayer mp) {
            mDialog.dismiss();
            mp.setLooping(false);
            videoView.start();
            btnPlayPause.setImageResource(R.drawable.ic_pause);
         }
     });
 }

这是包含 VideoView 和 ImageButton 的片段的 XML：

 <?xml version="1.0" encoding="utf-8"?>
 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:app="http://schemas.android.com/apk/res-auto"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:background="@android:color/background_light">

<TextView
    android:id="@+id/the_hypori_solution"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_alignParentTop="true"
    android:background="#b41518"
    android:padding="10dp"
    android:text="@string/the_hypori_solution"
    android:textAlignment="center"
    android:textColor="@android:color/background_light"
    android:textSize="30sp"
    android:textStyle="bold" />

<ScrollView
    android:id="@+id/solution_scroll_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_below="@id/the_hypori_solution">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center">

            <TextView
                android:id="@+id/virtualMobileInfrastructure"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerHorizontal="true"
                android:layout_marginTop="10dp"
                android:text="@string/virtual_mobile_infrastructure"
                android:textColor="@android:color/black"
                android:textSize="30sp"
                android:textStyle="italic" />

            <TextView
                android:id="@+id/vmi_info"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_below="@+id/virtualMobileInfrastructure"
                android:layout_marginTop="10dp"
                android:text="@string/vmi_info"
                android:textAlignment="center"
                android:textColor="@android:color/black"
                android:textSize="20sp" />

            <VideoView
                android:id="@+id/hypori_video"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_below="@+id/vmi_info"
                android:layout_centerHorizontal="true"/>

            <ImageButton
                android:id="@+id/play_pause_button"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_below="@+id/hypori_video"
                android:layout_centerHorizontal="true"
                app:srcCompat="@drawable/ic_play_arrow"/>

            <ImageView
                android:id="@+id/hypori_solution_image"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_below="@+id/play_pause_button"
                android:layout_centerHorizontal="true"
                android:layout_marginBottom="15dp"
                android:layout_marginTop="10dp"
                android:contentDescription="@string/hypori_solution_image"
                app:srcCompat="@drawable/hypori_solution__vertical_edited"/>

            <TextView
                android:id="@+id/solution_tv_vmi"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_below="@+id/hypori_solution_image"
                android:layout_centerHorizontal="true"
                android:layout_marginTop="5dp"
                android:text="@string/components_of_the_vmi_platform"
                android:textAlignment="center"
                android:textColor="@android:color/black"
                android:textSize="30sp" />

            <ImageView
                android:id="@+id/hypori_client_vmi"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_below="@id/solution_tv_vmi"
                android:layout_marginTop="10dp"
                android:layout_marginLeft="5dp"
                android:layout_marginStart="5dp"
                android:contentDescription="@string/hypori_client"
                app:srcCompat="@drawable/hypori_client" />

            <TextView
                android:id="@+id/hypori_client_vmi_tv1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignTop="@+id/hypori_client_vmi"
                android:layout_marginLeft="10dp"
                android:layout_marginStart="10dp"
                android:layout_toEndOf="@+id/hypori_client_vmi"
                android:layout_toRightOf="@+id/hypori_client_vmi"
                android:text="@string/hypori_client"
                android:textColor="@android:color/black"
                android:textSize="21sp"
                android:textStyle="bold" />

            <TextView
                android:id="@+id/hypori_client_vmi_tv2"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignLeft="@+id/hypori_client_vmi_tv1"
                android:layout_alignStart="@+id/hypori_client_vmi_tv1"
                android:layout_below="@+id/hypori_client_vmi_tv1"
                android:layout_marginTop="5dp"
                android:text="@string/"
                android:textColor="@android:color/black"
                android:textSize="17sp" />

            <ImageView
                android:id="@+id/hypori_vmd"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_below="@id/hypori_client_vmi_tv2"
                android:layout_marginTop="30dp"
                android:layout_marginLeft="5dp"
                android:layout_marginStart="5dp"
                android:contentDescription="@string/"
                app:srcCompat="@drawable/" />

            <TextView
                android:id="@+id/hypori_vmd_tv1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignLeft="@+id/hypori_client_vmi_tv1"
                android:layout_alignStart="@+id/hypori_client_vmi_tv1"
                android:layout_alignTop="@+id/hypori_vmd"
                android:text="@string/hypori_virtual_mobile_device"
                android:textColor="@android:color/black"
                android:textSize="21sp"
                android:textStyle="bold" />

            <TextView
                android:id="@+id/hypori_vmd_tv2"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignLeft="@id/hypori_client_vmi_tv1"
                android:layout_alignStart="@+id/hypori_client_vmi_tv1"
                android:layout_below="@+id/hypori_vmd_tv1"
                android:layout_marginTop="5dp"
                android:text="@string/
                android:textColor="@android:color/black"
                android:textSize="17sp" />

            <ImageView
                android:id="@+id/hypori_admin_console_iv"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_below="@id/hypori_vmd_tv2"
                android:layout_marginTop="30dp"
                android:layout_marginLeft="5dp"
                android:layout_marginStart="5dp"
                android:contentDescription="@string/hypori_admin_console"
                app:srcCompat="@drawable/hypori_admin_console" />

            <TextView
                android:id="@+id/hypori_admin_console_tv1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignLeft="@id/hypori_client_vmi_tv1"
                android:layout_alignStart="@+id/hypori_client_vmi_tv1"
                android:layout_alignTop="@+id/hypori_admin_console_iv"
                android:text="@string/hypori_admin_console"
                android:textColor="@android:color/black"
                android:textSize="21sp"
                android:textStyle="bold" />

            <TextView
                android:id="@+id/hypori_admin_console_tv2"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignLeft="@id/hypori_client_vmi_tv1"
                android:layout_alignStart="@+id/hypori_client_vmi_tv1"
                android:layout_below="@+id/hypori_admin_console_tv1"
                android:layout_marginTop="5dp"
                android:layout_marginBottom="5dp"
                android:text="@string/
                android:textColor="@android:color/black"
                android:textSize="17sp" />

        </RelativeLayout>

    </LinearLayout>

</ScrollView>

Answer 1

将您的活动类的标题更改为：

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

你忘了实现View.OnClickListener所以该onClick()方法不会覆盖任何内容