我正在创建一个音乐应用。我想从主要活动发送广播。接收者也是主要活动。这个广播访问创建并显示为片段的Arraylist。每个片段都在视图寻呼机中。 view pager是主要活动。
现在的问题是我发送广播来访问arraylist和接收者接收（从主类的oncreate方法发送广播）但是仍然没有创建arraylist所以没有数据存在，所以它显示错误。 在生成arraylist并创建了片段之后，有什么方法可以发送广播吗？
public class MainActivity extends AppCompatActivity implements SeekBar.OnSeekBarChangeListener{
private static int songEnded = 0;
View view;
Intent intent;
int a = 0, b = 0;
int x=0;
String[] path = Kaibee.getInstance().path;
ArrayList<collection> collections;
ArrayList<collection> songlist = Kaibee.getInstance().collections;
ArrayList<collection> fav = fav_collection.getInstance().fav;
TextView bsongname,starttime,endtime;
collectionAdapter collectionadapter=new favorite().mAdapter;
ImageView bsongimage;
int seekProgress;
ImageButton greenplay,favourite;
RelativeLayout songinfo, rl;
LinearLayout bottomll;
View bottomSheet;
FloatingActionButton fb;
MediaPlayer mediaPlayer;
ImageView bnext,bprev,playlist;
favlistdb mydb;
bottomsheetdb bdb;
playerservice ps;
favorite f=new favorite();
private BottomSheetBehavior mBottomSheetBehavior;
private SeekBar seekBar;
private int seekMax;
private Toolbar toolbar;
ActionBarDrawerToggle actionBarDrawerToggle;
DrawerLayout drawerLayout;
private BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent serviceIntent) {
updateUI(serviceIntent);
}
};
private IntentFilter bfilter = new IntentFilter("songclick");
private IntentFilter filter = new IntentFilter("songc");
// private IntentFilter pfilter = new IntentFilter("bottomsheetbutton");
@Override
protected void onRestart() {
super.onRestart();
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
LocalBroadcastManager.getInstance(getApplicationContext()).registerReceiver(bBroadcastReceiver, bfilter);
LocalBroadcastManager.getInstance(getApplicationContext()).registerReceiver(broadcastReceiver, filter);
ps= new playerservice();
bdb = new bottomsheetdb(this);
Cursor result=bdb.getdata();
if (result != null) {
int pos=0;
String listname = null;
if (result.moveToFirst() ) {
do{
listname = result.getString(result.getColumnIndex(bottomsheetdb.COL_2)) ;
pos =(result.getInt(result.getColumnIndex(String.valueOf(bottomsheetdb.COL_3))));
System.out.println("bottomsheet data "+listname+" "+pos);
Intent minten = new Intent("songclick");
minten.addFlags(Intent.FLAG_INCLUDE_STOPPED_PACKAGES);
minten.putExtra("position",pos);
minten.putExtra("pause","play");
minten.putExtra("collect",listname);
LocalBroadcastManager.getInstance(getApplicationContext()).sendBroadcast(minten);
ps.setupHandler();
}while(result.moveToNext());
}
}
else{bottomSheet.setVisibility(View.GONE);}
// Create an adapter that knows which fragment should be shown on each page
category_adapter adapter = new category_adapter(this, getSupportFragmentManager());
// Set the adapter onto the view pager
viewPager.setAdapter(adapter);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
// Connect the tab layout with the view pager. This will
// 1. Update the tab layout when the view pager is swiped
// 2. Update the view pager when a tab is selected
// 3. Set the tab layout's tab names with the view pager's adapter's titles
// by calling onPageTitle()
tabLayout.setupWithViewPager(viewPager);
//setting data inside bottom sheet
try {
Intent serviceIntent = new Intent(this, playerservice.class);
// --- set up seekbar intent for broadcasting new position to service ---
intent = new Intent("seek_update");
seekBar.setOnSeekBarChangeListener(this);
}
catch (Exception e) {
e.printStackTrace();
Toast.makeText(getApplicationContext(),
e.getClass().getName() + " " + e.getMessage(),
Toast.LENGTH_LONG).show();
}
}
public BroadcastReceiver bBroadcastReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context c, Intent i) {
x=0;
String ss=i.getExtras().getString("collect");
if(ss.equals("song_list_fragment")){collections=Kaibee.getInstance().collections;}
else if(ss.equals("album")){collections=song_album_fetch.getInstance().albumsong;}
else if(ss.equals("artist")){collections=artist_songs_fetch.getInstance().artistsong;}
else if(ss.equals("genres")){collections=genres_songs_fetch.getInstance().genresong;
}
else{collections=fav_collection.getInstance().fav;}
a = i.getExtras().getInt("position");
collectionadapter=new collectionAdapter(getApplicationContext(),fav);
// collectionadapter=f.mAdapter;
String s = i.getExtras().getString("pause");
String play = "play", pause = "pause";
if (s.equals(play)) {
greenplay.setImageResource(R.drawable.ic_play_circle_filled);
fb.setImageResource(R.drawable.ic_play_arrow);
} else {
greenplay.setImageResource(R.drawable.ic_pause_circle_outline);
fb.setImageResource(R.drawable.ic_pause);
}
bottomSheet.setVisibility(View.VISIBLE);
}
};
/**
* Dispatch onResume() to fragments. Note that for better inter-operation
* with older versions of the platform, at the point of this call the
* fragments attached to the activity are <em>not</em> resumed. This means
* that in some cases the previous state may still be saved, not allowing
* fragment transactions that modify the state. To correctly interact
* with fragments in their proper state, you should instead override
* {@link #onResumeFragments()}.
*/
@Override
protected void onResume() {
super.onResume();
}
@Override
protected void onDestroy() {
super.onDestroy();
LocalBroadcastManager.getInstance(getApplicationContext()).unregisterReceiver(bBroadcastReceiver);
LocalBroadcastManager.getInstance(getApplicationContext()).unregisterReceiver(broadcastReceiver);
}
}
答案 0 :(得分：0)
注册广播接收器的方法：
private MyReceiver mMyReceiver;
private class mMyReceiver extends BroadcastReceiver {
Context mContext;
public mMyReceiver(Context context){
mContext = context;
}
@Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(YOUR_ACTION)) {
// get data from intent
}
}
}
private void registerReceiver() {
if (mMyReceiver== null) {
mMyReceiver= new MyReceiver(this);
}
IntentFilter intentFilter = new IntentFilter(YOUR_ACTION);
registerReceiver(mMyReceiver, intentFilter);
}
在onCreate和onDestroy中：
@Override
protected void onCreate(Bundle savedInstanceState) {
// others
registerReceiver();
}
@Override
protected void onDestroy() {
if(mMyReceiver != null){
unregisterReceiver(mMyReceiver );
}
super.onDestroy();
}
注意：如果活动相同，请考虑其他方式
答案 1 :(得分：0)
使用以下代码来实现目标......
registerReceiver(myReceiver, new IntentFilter("INTENT_NAME"));
private BroadcastReceiver myReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
}
};
---------------- 使用发送 --------------- ------------------
Intent intent = new Intent("INTENT_NAME");
sendBroadcast(intent);
答案 2 :(得分：0)
发送广播时，对接收方的呼叫将发布在主线程工作队列的末尾。如果您注册接收器并在onCreate中发送广播，则在onCreate返回后的某个时间才会调用接收器。其他活动生命周期方法可能已经在队列中，因此他们还必须在调用接收者之前运行并返回。