我试图检测我的应用的连接状态，但这是面临的错误：
Failed to convert value of type java.util.HashMap to boolean
我正在使用Firebase。错误在线：
boolean connected = dataSnapshot.getValue(Boolean.class);
因此，错误来自OnDataFinishedLoading()方法。数据首先出现，但现在我只想检测应用程序网络连接。以下是我的代码：
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
public static String KEY_HEADLINES="headlines";
public static String KEY_DETAILS="details";
// private static final String TAG = "Ask Doctor App";
ProgressBar pb;
public List<NewsModel> newslist;
public NewsAdapter2 adapter;
private RecyclerView mRecyclerView;
private DatabaseReference mRef;
ImageView image_news;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// call the array list
newslist = new ArrayList<NewsModel>();
pb = (ProgressBar) findViewById(R.id.progressBarNews);
image_news =(ImageView) findViewById(R.id.image_news);
mRecyclerView = (RecyclerView) findViewById(R.id.recycler_view);
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
//Enabling offline capabilities
FirebaseDatabase.getInstance().setPersistenceEnabled(true);
// firebase initialisation......
mRef = FirebaseDatabase.getInstance().getReference("News");
// keep my data synced
mRef.keepSynced(true);
OnDataFinishedLoading();
// load data
//declare the toolbar
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
//NetworkInfo netInfo = cm.getActiveNetworkInfo();
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
/* if (isOnline()) {
Snackbar.make(view, "Refreshing news ....", Snackbar.LENGTH_LONG)
.setAction("Thanks.", null).show();
} else {
Snackbar.make(view, "There's a Network problem", Snackbar.LENGTH_LONG)
.setAction("", null).show();
}
Snackbar.make(view, "Refreshing news ....", Snackbar.LENGTH_LONG)
.setAction("Thanks.", null).show();*/
}
});
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
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);
}
private void OnDataFinishedLoading(){
mRef.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
boolean connected = dataSnapshot.getValue(Boolean.class);
if(connected) {
pb.setVisibility(View.INVISIBLE);
LoadData(dataSnapshot);
} else{
Toast.makeText(MainActivity.this,"No Network",Toast.LENGTH_LONG).show();
}
}
@Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
LoadData(dataSnapshot);
}
@Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
public void LoadData (DataSnapshot dataSnapshot){
System.out.println(dataSnapshot.getValue());
NewsModel news_model =dataSnapshot.getValue(NewsModel.class);
newslist.add(news_model);
adapter = new NewsAdapter2(MainActivity.this, newslist);
mRecyclerView.setAdapter(adapter);
}
/* protected boolean isOnline() {
ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo netInfo = cm.getActiveNetworkInfo();
if (netInfo != null && netInfo.isConnectedOrConnecting()) {
return true;
} else {
return false;
}
}
*/
@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 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) {
// Handle navigation view item clicks here.
int id = item.getItemId();
Intent i;
if (id == R.id.hospitals) {
i = new Intent(MainActivity.this, HealthCentres.class);
startActivity(i);
} else if (id == R.id.doctors) {
i = new Intent(MainActivity.this, Doctors.class);
startActivity(i);
} /*else if (id == R.id.location) {
i = new Intent(MainActivity.this, Location.class);
startActivity(i);
} */else if (id == R.id.tips) {
i = new Intent(MainActivity.this, Tips.class);
startActivity(i);
} /*else if (id == R.id.faq) {
}
*/
/*
else if (id == R.id.suggestions) {
}
*/
else if (id == R.id.contacts) {
i= new Intent(MainActivity.this, ContactUs.class);
startActivity(i);
}
/*
else if (id == R.id.settings) {
}
*/
else if (id == R.id.about) {
i = new Intent(MainActivity.this, AboutUs.class);
startActivity(i);
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
}
答案 0 :(得分：0)
好的，所以你遇到的核心问题是Firebase正在返回一个Map，而不是一个布尔值。这是因为您配置了这种方式 - 每次添加子项时，您都会尝试查看DataSnapshot（这是您设置的侦听器所做的事情），并尝试获取布尔值。但是，快照是添加到数据库中的子项（而不是布尔值），因此您可以获取地图。
如果您只想验证孩子是否成功添加，我会执行以下操作：
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
Object value = dataSnapshot.getValue();
if(value != null) {
pb.setVisibility(View.INVISIBLE);
LoadData(dataSnapshot);
} else{
Toast.makeText(MainActivity.this,"No Network",Toast.LENGTH_LONG).show();
}
}
但是，这并不能真正解决您的网络连接问题。每当非空子项被添加到firebase对象时，它就会发生这种情况，这可能经常发生。同样在LoadData中，您不检查以确保传入的对象不为空。