在我的MainActivity中，我有“setContentView（R.layout.activity_main）”。此activity_main布局包含VideoView。
activity_main未在任何片段中使用; 当我切换到片段时我看不到视频（这是好的），但是如果我点击屏幕，那么视频选项（播放，暂停等）会弹出（不好）。我假设main_activity位于每个片段的下面，因为“setContentView（R.layout.activity_main）”？
我需要将视频显示在一个片段中，而不会影响任何其他片段。但是，如果我尝试从activity_main中删除VideoView，而是在片段布局中识别它（即fragment_one ），我得到一个NullPointerException。我再次认为这是因为“setContentView（R.layout.activity_main）”。我认为必须在activity_main中识别java代码中引用的视图（id =“@ + id / video_view”）？
这个问题的解决方案可能非常简单，但我似乎无法找到解决它的任何信息。我当然是新手，所以请耐心等待。
这是我的MainActivity：
public class MainActivity extends AppCompatActivity {
//used in VideoView
private VideoView myVideoView;
private int position = 0;
private ProgressDialog progressDialog;
private MediaController mediaControls;
String[] LabelMenu = {"Home","Flight Tracker"};
@Override
//Allows the use of icons in overflow-dropdown
protected boolean onPrepareOptionsPanel(View view, Menu menu) {
if (menu != null) {
if (menu.getClass().getSimpleName().equals("MenuBuilder")) {
try {
Method m = menu.getClass().getDeclaredMethod(
"setOptionalIconsVisible", Boolean.TYPE);
m.setAccessible(true);
m.invoke(menu, true);
} catch (Exception e) {
Log.e(getClass().getSimpleName(), "onMenuOpened...unable to set icons for overflow menu", e);
}
}
}
return super.onPrepareOptionsPanel(view, menu);
}
//***START OF GOTOURL REFERENCES***
public void goToUS (View view) {
goToUrl ( "http://10.100.1.200/imsg_weather_radar/weather_radar_united_states.html");
}
public void goToSW (View view) {
goToUrl( "http://10.100.1.200/imsg_weather_radar/weather_radar_southwest_us.html");
}
public void goToSE (View view) {
goToUrl("http://10.100.1.200/imsg_weather_radar/weather_radar_southeast_us.html");
}
public void goToNW (View view) {
goToUrl("http://10.100.1.200/imsg_weather_radar/weather_radar_northwest_us.html");
}
public void goToWP (View view) {
goToUrl("http://10.100.1.200/imsg_weather_radar/weather_radar_west_pacific.html");
}
public void goToSP (View view) {
goToUrl("http://10.100.1.200/imsg_weather_radar/weather_radar_south_pacific.html");
}
public void goToCC (View view) {
goToUrl("http://10.100.1.200/imsg_weather_radar/weather_radar_carolina_coast.html");
}
public void goToWA (View view) {
goToUrl("http://10.100.1.200/imsg_weather_radar/weather_radar_western_atlantic.html");
}
public void goToEU (View view) {
goToUrl("http://10.100.1.200/imsg_weather_radar/weather_radar_eastern_us.html");
}
public void goToEGF (View view) {
goToUrl("http://10.100.1.200/imsg_weather_radar/weather_radar_east_gulf_florida.html");
}
public void goToGM (View view) {
goToUrl("http://10.100.1.200/imsg_weather_radar/weather_radar_gulf_of_mexico.html");
}
public void goToWGT (View view) {
goToUrl("http://10.100.1.200/imsg_weather_radar/weather_radar_west_gulf_texas.html");
}
public void goToCI (View view) {
goToUrl("http://10.100.1.200/imsg_weather_radar/weather_radar_caribbean_islands.html");
}
public void goToMX (View view) {
goToUrl("http://10.100.1.200/imsg_weather_radar/weather_radar_mexico.html");
}
public void goToCA (View view) {
goToUrl("http://10.100.1.200/imsg_weather_radar/weather_radar_central_america.html");
}
//***END OF GOTOURL REFERENCES***
private void goToUrl (String url) {
Uri uriUrl = Uri.parse(url);
Intent launchBrowser = new Intent(Intent.ACTION_VIEW, uriUrl);
startActivity(launchBrowser);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Set the main layout of activity
setContentView(R.layout.activity_main);
//set the media controller buttons
if (mediaControls == null) {
mediaControls = new MediaController(MainActivity.this);
}
//initialize the VideoView
myVideoView = (VideoView) findViewById(R.id.video_view);
// create a progress bar while the video file is loading
progressDialog = new ProgressDialog(MainActivity.this);
// set a title for the progress bar
progressDialog.setTitle("IAWS");
// set a message for the progress bar
progressDialog.setMessage("Loading...");
//set the progress bar not cancelable on users' touch
progressDialog.setCancelable(false);
// show the progress bar
progressDialog.show();
try {
//set the media controller in the VideoView
myVideoView.setMediaController(mediaControls);
//set the uri of the video to be played
myVideoView.setVideoURI(Uri.parse("android.resource://" + getPackageName() + "/" + R.raw.iaws));
} catch (Exception e) {
if(e.getMessage()!=null) {
Log.e("Error", e.getMessage());
e.printStackTrace();
}
}
myVideoView.requestFocus();
//setOnPreparedListener in order to know when the video file is ready for playback
myVideoView.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
public void onPrepared(MediaPlayer mediaPlayer) {
// close the progress bar and play the video
progressDialog.dismiss();
//if we have a position on savedInstanceState, the video playback should start from here
myVideoView.seekTo(position);
if (position == 0) {
//remove comments if you want video to start automatically
//myVideoView.start();
} else {
//coming from a resumed activity, video playback will be paused
myVideoView.pause();
}
}
});
final ActionBar actionBar = getSupportActionBar();
// Specify that a dropdown list should be displayed in the action bar.
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);
// Hide the title
actionBar.setDisplayShowTitleEnabled(false);
actionBar.setDisplayUseLogoEnabled(false);
//Adding an ImageView to Action Bar
actionBar.setDisplayOptions(actionBar.getDisplayOptions()
| ActionBar.DISPLAY_SHOW_CUSTOM);
ImageView imageView = new ImageView(actionBar.getThemedContext());
imageView.setScaleType(ImageView.ScaleType.CENTER);
imageView.setImageResource(R.drawable.imsg_blue_logo_rsz);
ActionBar.LayoutParams layoutParams = new ActionBar.LayoutParams(
ActionBar.LayoutParams.WRAP_CONTENT,
ActionBar.LayoutParams.WRAP_CONTENT, Gravity.RIGHT
| Gravity.CENTER_VERTICAL);
layoutParams.rightMargin = 40;
layoutParams.bottomMargin=10;
imageView.setLayoutParams(layoutParams);
actionBar.setCustomView(imageView);
// Specify a SpinnerAdapter to populate the dropdown list.
ArrayAdapter<String> spinnerMenu = new ArrayAdapter<String>(actionBar.getThemedContext(), android.R.layout.simple_list_item_1, getResources().getStringArray(R.array.labelMenu));
//2nd Spinner dropdown
/**
Spinner mySpinner = (Spinner)findViewById(R.id.spinner);
mySpinner.setAdapter(new MyCustomAdapter(MainActivity.this, R.layout.row, LabelMenu));
**/
actionBar.setListNavigationCallbacks(spinnerMenu,
// Provide a listener to be called when an item is selected.
new ActionBar.OnNavigationListener() {
public boolean onNavigationItemSelected(int position, long id) {
// Take action here, e.g. switching to the
// corresponding fragment.
FragmentTransaction tx = getFragmentManager().beginTransaction();
switch (position) {
case 0:
tx.replace(android.R.id.content, new FirstFragment());
break;
case 1:
tx.replace(android.R.id.content, new SecondFragment());
break;
case 2:
tx.replace(android.R.id.content, new ThirdFragment());
break;
case 3:
tx.replace(android.R.id.content, new FourthFragment());
break;
case 4:
tx.replace(android.R.id.content, new FifthFragment());
break;
default:
break;
}
tx.commit();
return true;
}
});
}
@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
super.onSaveInstanceState(savedInstanceState);
// Use onSaveInstanceState in order to store the video playback position for orientation change
savedInstanceState.putInt("Position", myVideoView.getCurrentPosition());
myVideoView.pause();
}
@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
// Use onRestoreInstanceState in order to play the video playback from the stored position
position = savedInstanceState.getInt("Position");
myVideoView.seekTo(position);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item){
super.onOptionsItemSelected(item);
switch(item.getItemId()){
case R.id.about:
aboutMenuItem();
break;
case R.id.settings:
settingsMenuItem();
break;
case R.id.search:
searchMenuItem();
break;
}
return true;
}
//Configure "about" function
private void aboutMenuItem(){
new AlertDialog.Builder(this)
.setTitle("App & Copyright Info")
.setMessage("Version 1.0" + "\n" + "Property of I.M. Systems Group, Inc.")
.setNeutralButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
}).show();{
}
}
//Configure "settings" function
private void settingsMenuItem(){
new AlertDialog.Builder(this)
.setTitle("Settings")
.setMessage("Language: English" + "\n" + "Degrees Fahrenheit Selected" + "\n" +
"Show Airports" + "\n" + "Speed: KM/H" )
.setNeutralButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
}).show();{
}
}
//Configure "search" function
private void searchMenuItem(){
new AlertDialog.Builder(this)
.setTitle("Search")
.setMessage("This is an about AlertDialog")
.setNeutralButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
}).show();{
}
}
}
我想让这个片段专门显示视频。 就像现在一样，片段会很好地显示他们指定的布局，但是如果你在任何布局中点击屏幕，main_activity的VideoView中的视频选项会弹出（这很糟糕）。他们是几乎都以相同的方式编码;它们的不同之处在于它们引用了不同的布局：
/**
* Created by ansaripours on 8/19/2015.
*/
public class FirstFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
View view = inflater.inflate(R.layout.fragment_one, container, false);
return (FrameLayout) inflater.inflate(R.layout.fragment_one, container, false);
}
}
这是我的main_activity.xml。看来ViewVideo似乎必须在这里标识，因为它在setContentView中被引用，否则我得到一个NullPointerException：
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_gravity="center"
android:background="#E1F4FF"
android:paddingTop="?android:attr/actionBarSize"
tools:context=".MainActivity">
<!-- implementing swipeable pages
<edu.dartmouth.cs.actiontabs.view.SlidingTabLayout
android:id="@+id/tab"
android:layout_width="fill_parent"
android:layout_height="wrap_content"/>
<android.support.v4.view.ViewPager
android:id="@+id/viewpager"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_below="@+id/tab"/>
-->
<!--
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_gravity="center"
android:padding="100"/>-->
<!--
<Spinner
android:id="@+id/spinner"
android:layout_width="fill_parent"
android:layout_height="wrap_content" /> -->
<!--
<ImageView
android:src="@drawable/rsz_sampleweather"
android:id="@+id/cover_view"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:scaleType="centerCrop"
/>
-->
<VideoView
android:id="@+id/video_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="center"/>
</FrameLayout>
最后，这是FirstFragment类引用的布局。它与main_activity.xml完全相同（没有注释）。但是，就像我说的，如果我从main_activity.xml中删除VideoView，我会得到一个NullPointerException。
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_gravity="center"
android:background="#E1F4FF"
android:paddingTop="?android:attr/actionBarSize"
tools:context=".MainActivity">
<VideoView
android:id="@+id/video_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="center"/>
</FrameLayout>
随意提出任何问题。任何见解都会非常感激。
答案 0 :(得分：1)
首先，我建议您阅读有关如何使用片段的Android开发者页面：http://developer.android.com/guide/components/fragments.html。
您应该能够在activity_main.xml中为片段定义容器，并创建一个单独的片段来保存您的VideoView，可以使用FragmentTransaction替换为另一个片段。