单击进入聊天室时应用程序崩溃
App crashed when click into chat room
我在我的应用程序中使用这个 link 的聊天室。
https://gist.github.com/puf/f49a1b07e92952b44f2dc36d9af04e3c
我的应用流程：
登录 -> MainActivity -> select 来自列表视图的团队加入聊天 -> ChatRoomActivity
我的问题是，当我在列表视图中单击其中一个团队时，它崩溃了。我的聊天室代码与 link 完全相同，除了我将 MainActivity 更改为 ChatRoomActivity 并删除了登录弹出窗口。剩下的就是same.Can有人帮我改正或查明原因吗？
主要活动：
public class MainActivity extends AppCompatActivity {
public static final String TEAM_NAME = "com.example.user.stfv2.teamname";
public static final String TEAM_ID = "com.example.user.stfv2.teamid";
private FirebaseAuth firebaseAuth;
EditText editTextName;
EditText textDate;
EditText textTime;
Spinner spinnerSport;
Button buttonAddTeam;
ListView listViewTeams;
DatePickerDialog datePickerDialog;
List<Team> teams;
DatabaseReference databaseTeams;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
firebaseAuth = FirebaseAuth.getInstance();
if(firebaseAuth.getCurrentUser() == null){
finish();
startActivity(new Intent(this, SignInActivity.class));
}
FirebaseUser user = firebaseAuth.getCurrentUser();
databaseTeams = FirebaseDatabase.getInstance().getReference("teams");
editTextName = (EditText) findViewById(R.id.editTextName);
spinnerSport = (Spinner) findViewById(R.id.spinnerSports);
listViewTeams = (ListView) findViewById(R.id.listViewTeams);
textDate = (EditText) findViewById(R.id.textDate);
textTime = (EditText) findViewById(R.id.textTime);
buttonAddTeam = (Button) findViewById(R.id.buttonAddTeam);
teams = new ArrayList<>();
buttonAddTeam.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent myIntent = new Intent(MainActivity.this,
AddActivity.class);
startActivity(myIntent);
}
});
listViewTeams.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
Team team = teams.get(i);
Intent intent = new Intent(getApplicationContext(), ChatRoomActivity.class);
intent.putExtra(TEAM_ID, team.getTeamId());
intent.putExtra(TEAM_NAME, team.getTeamName());
startActivity(intent);
}
});
listViewTeams.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> adapterView, View view, int i, long l) {
Team team = teams.get(i);
showUpdateDeleteDialog(team.getTeamId(), team.getTeamName());
return true;
}
});
}
private void showUpdateDeleteDialog(final String teamId, String teamName) {
AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(this);
LayoutInflater inflater = getLayoutInflater();
final View dialogView = inflater.inflate(R.layout.update_dialog, null);
dialogBuilder.setView(dialogView);
final EditText editTextName = (EditText) dialogView.findViewById(R.id.editTextName);
final Spinner spinnerSport = (Spinner) dialogView.findViewById(R.id.spinnerSports);
final Button buttonUpdate = (Button) dialogView.findViewById(R.id.buttonUpdateTeam);
final Button buttonDelete = (Button) dialogView.findViewById(R.id.buttonDeleteTeam);
final EditText textDate = (EditText) dialogView.findViewById(R.id.textDate);
final EditText textTime = (EditText) dialogView.findViewById(R.id.textTime);
dialogBuilder.setTitle(teamName);
final AlertDialog b = dialogBuilder.create();
b.show();
textDate.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
final Calendar c = Calendar.getInstance();
int mYear = c.get(Calendar.YEAR);
int mMonth = c.get(Calendar.MONTH);
int mDay = c.get(Calendar.DAY_OF_MONTH);
datePickerDialog = new DatePickerDialog(MainActivity.this,
new DatePickerDialog.OnDateSetListener() {
@Override
public void onDateSet(DatePicker view, int year,
int monthOfYear, int dayOfMonth) {
textDate.setText(dayOfMonth + "/"
+ (monthOfYear + 1) + "/" + year);
}
}, mYear, mMonth, mDay);
datePickerDialog.show();
}
});
textTime.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Calendar mcurrentTime = Calendar.getInstance();
int hour = mcurrentTime.get(Calendar.HOUR_OF_DAY);
int minute = mcurrentTime.get(Calendar.MINUTE);
TimePickerDialog mTimePicker;
mTimePicker = new TimePickerDialog(MainActivity.this, new TimePickerDialog.OnTimeSetListener() {
@Override
public void onTimeSet(TimePicker timePicker, int selectedHour, int selectedMinute) {
textTime.setText(selectedHour + ":" + selectedMinute);
}
}, hour, minute, true);
mTimePicker.setTitle("Select Time");
mTimePicker.show();
}
});
buttonUpdate.setOnClickListener(new View.OnClickListener() {
FirebaseUser user = firebaseAuth.getCurrentUser();
@Override
public void onClick(View view) {
String name = editTextName.getText().toString().trim();
String sport = spinnerSport.getSelectedItem().toString();
String owner = user.getUid();
String date = textDate.getText().toString();
String time = textTime.getText().toString();
if (!TextUtils.isEmpty(name)) {
updateTeam(teamId, name, sport, owner, date, time);
b.dismiss();
}
}
});
buttonDelete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
deleteTeam(teamId);
b.dismiss();
}
});
}
private boolean updateTeam(String id, String name, String sport, String owner, String date, String time) {
DatabaseReference dR = FirebaseDatabase.getInstance().getReference("teams").child(id);
Team team = new Team(id, name, sport, owner, date, time);
dR.setValue(team);
Toast.makeText(getApplicationContext(), "Team Updated", Toast.LENGTH_LONG).show();
return true;
}
private boolean deleteTeam(String id) {
DatabaseReference dR = FirebaseDatabase.getInstance().getReference("teams").child(id);
dR.removeValue();
DatabaseReference drTracks = FirebaseDatabase.getInstance().getReference("tracks").child(id);
drTracks.removeValue();
Toast.makeText(getApplicationContext(), "Team Deleted", Toast.LENGTH_LONG).show();
return true;
}
@Override
protected void onStart() {
super.onStart();
databaseTeams.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
teams.clear();
for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
Team team = postSnapshot.getValue(Team.class);
teams.add(team);
}
TeamList teamAdapter = new TeamList(MainActivity.this, teams);
listViewTeams.setAdapter(teamAdapter);
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.action_logout:
firebaseAuth.signOut();
finish();
startActivity(new Intent(this, SignInActivity.class));
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
Logcat:
03-19 01:40:25.709 2995-2995/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.user.stfv2, PID: 2995
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.user.stfv2/com.example.user.stfv2.ChatRoomActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at com.example.user.stfv2.ChatRoomActivity.setUsername(ChatRoomActivity.java:58)
at com.example.user.stfv2.ChatRoomActivity.onCreate(ChatRoomActivity.java:73)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
编辑 1：
layout_chat_room:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
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"
tools:context="com.example.user.stfv2.MainActivity">
<RelativeLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/header"
android:gravity="end">
<ImageView
android:layout_width="36dp"
android:layout_height="36dp"
android:id="@+id/userIcon"
android:foregroundGravity="center"
android:layout_alignParentStart="true"
android:layout_alignParentLeft="true" />
<TextView
android:layout_width="141dp"
android:layout_height="wrap_content"
android:id="@+id/usernameTxt"
android:layout_toRightOf="@+id/userIcon"
android:layout_alignTop="@+id/userIcon"
android:layout_alignBottom="@+id/userIcon"
android:gravity="center_vertical"
tools:text="Username"
android:layout_weight="0" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Sign in"
android:id="@+id/loginBtn"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Sign out"
android:id="@+id/logoutBtn"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true" />
</RelativeLayout>
<android.support.v7.widget.RecyclerView
android:id="@+id/messagesList"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
tools:listitem="@android:layout/two_line_list_item"
android:layout_above="@+id/footer"
android:layout_below="@+id/header" />
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:id="@+id/footer">
<ImageButton
android:layout_width="36dp"
android:layout_height="36dp"
android:id="@+id/imageBtn"
android:background="@android:drawable/ic_menu_gallery" />
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/messageTxt"
android:layout_gravity="bottom"
android:layout_weight="1"
android:inputType="textShortMessage|textAutoCorrect" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Send"
android:id="@+id/sendBtn"
android:layout_gravity="bottom" />
</LinearLayout>
</RelativeLayout>
聊天室活动：
public class ChatRoomActivity extends AppCompatActivity {
private static final String TAG = "ChatRoomActivity";
static final int RC_PHOTO_PICKER = 1;
private Button sendBtn;
private EditText messageTxt;
private RecyclerView messagesList;
private ChatMessageAdapter adapter;
private ImageButton imageBtn;
private TextView usernameTxt;
private View loginBtn;
private View logoutBtn;
private FirebaseApp app;
private FirebaseDatabase database;
private FirebaseAuth auth;
private FirebaseStorage storage;
private DatabaseReference databaseRef;
private StorageReference storageRef;
private String username;
private void setUsername(String username) {
Log.d(TAG, "setUsername("+String.valueOf(username)+")");
if (username == null) {
username = "Android";
}
boolean isLoggedIn = !username.equals("Android");
this.username = username;
this.usernameTxt.setText(username);
this.logoutBtn.setVisibility(isLoggedIn ? View.VISIBLE : View.GONE);
this.loginBtn .setVisibility(isLoggedIn ? View.GONE : View.VISIBLE);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
sendBtn = (Button) findViewById(R.id.sendBtn);
messageTxt = (EditText) findViewById(R.id.messageTxt);
messagesList = (RecyclerView) findViewById(R.id.messagesList);
imageBtn = (ImageButton) findViewById(R.id.imageBtn);
loginBtn = findViewById(R.id.loginBtn);
logoutBtn = findViewById(R.id.logoutBtn);
usernameTxt = (TextView) findViewById(R.id.usernameTxt);
setUsername("Android");
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
messagesList.setHasFixedSize(false);
messagesList.setLayoutManager(layoutManager);
// Show an image picker when the user wants to upload an imasge
imageBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("image/jpeg");
intent.putExtra(Intent.EXTRA_LOCAL_ONLY, true);
startActivityForResult(Intent.createChooser(intent, "Complete action using"), RC_PHOTO_PICKER);
}
});
// Show a popup when the user asks to sign in
loginBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
LoginDialog.showLoginPrompt(ChatRoomActivity.this, app);
}
});
// Allow the user to sign out
logoutBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
auth.signOut();
}
});
adapter = new ChatMessageAdapter(this);
messagesList.setAdapter(adapter);
adapter.registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {
public void onItemRangeInserted(int positionStart, int itemCount) {
messagesList.smoothScrollToPosition(adapter.getItemCount());
}
});
// Get the Firebase app and all primitives we'll use
app = FirebaseApp.getInstance();
database = FirebaseDatabase.getInstance(app);
auth = FirebaseAuth.getInstance(app);
storage = FirebaseStorage.getInstance(app);
// Get a reference to our chat "room" in the database
databaseRef = database.getReference("chat");
sendBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
ChatMessage chat = new ChatMessage(username, messageTxt.getText().toString());
// Push the chat message to the database
databaseRef.push().setValue(chat);
messageTxt.setText("");
}
});
// Listen for when child nodes get added to the collection
databaseRef.addChildEventListener(new ChildEventListener() {
public void onChildAdded(DataSnapshot snapshot, String s) {
// Get the chat message from the snapshot and add it to the UI
ChatMessage chat = snapshot.getValue(ChatMessage.class);
adapter.addMessage(chat);
}
public void onChildChanged(DataSnapshot dataSnapshot, String s) { }
public void onChildRemoved(DataSnapshot dataSnapshot) { }
public void onChildMoved(DataSnapshot dataSnapshot, String s) { }
public void onCancelled(DatabaseError databaseError) { }
});
// When the user has entered credentials in the login dialog
LoginDialog.onCredentials(new OnSuccessListener<LoginDialog.EmailPasswordResult>() {
public void onSuccess(LoginDialog.EmailPasswordResult result) {
// Sign the user in with the email address and password they entered
auth.signInWithEmailAndPassword(result.email, result.password);
}
});
// When the user signs in or out, update the username we keep for them
auth.addAuthStateListener(new FirebaseAuth.AuthStateListener() {
public void onAuthStateChanged(FirebaseAuth firebaseAuth) {
if (firebaseAuth.getCurrentUser() != null) {
// User signed in, set their email address as the user name
setUsername(firebaseAuth.getCurrentUser().getEmail());
}
else {
// User signed out, set a default username
setUsername("Android");
}
}
});
}
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == RC_PHOTO_PICKER && resultCode == RESULT_OK) {
Uri selectedImageUri = data.getData();
// Get a reference to the location where we'll store our photos
storageRef = storage.getReference("chat_photos");
// Get a reference to store file at chat_photos/<FILENAME>
final StorageReference photoRef = storageRef.child(selectedImageUri.getLastPathSegment());
// Upload file to Firebase Storage
photoRef.putFile(selectedImageUri)
.addOnSuccessListener(this, new OnSuccessListener<UploadTask.TaskSnapshot>() {
public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
// When the image has successfully uploaded, we get its download URL
Uri downloadUrl = taskSnapshot.getDownloadUrl();
// Set the download URL to the message box, so that the user can send it to the database
messageTxt.setText(downloadUrl.toString());
}
});
}
}
}
您的问题是您定义了错误的 XML 文件。当您使用 ChatroomActivity 中的代码时，您忘记更改 XML 文件。目前设置为setContentView(R.layout.activity_main)，但应该是setContentView(R.layout.layout_chat_room)。
我在我的应用程序中使用这个 link 的聊天室。
https://gist.github.com/puf/f49a1b07e92952b44f2dc36d9af04e3c
我的应用流程：
登录 -> MainActivity -> select 来自列表视图的团队加入聊天 -> ChatRoomActivity
我的问题是，当我在列表视图中单击其中一个团队时，它崩溃了。我的聊天室代码与 link 完全相同，除了我将 MainActivity 更改为 ChatRoomActivity 并删除了登录弹出窗口。剩下的就是same.Can有人帮我改正或查明原因吗？
主要活动：
public class MainActivity extends AppCompatActivity {
public static final String TEAM_NAME = "com.example.user.stfv2.teamname";
public static final String TEAM_ID = "com.example.user.stfv2.teamid";
private FirebaseAuth firebaseAuth;
EditText editTextName;
EditText textDate;
EditText textTime;
Spinner spinnerSport;
Button buttonAddTeam;
ListView listViewTeams;
DatePickerDialog datePickerDialog;
List<Team> teams;
DatabaseReference databaseTeams;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
firebaseAuth = FirebaseAuth.getInstance();
if(firebaseAuth.getCurrentUser() == null){
finish();
startActivity(new Intent(this, SignInActivity.class));
}
FirebaseUser user = firebaseAuth.getCurrentUser();
databaseTeams = FirebaseDatabase.getInstance().getReference("teams");
editTextName = (EditText) findViewById(R.id.editTextName);
spinnerSport = (Spinner) findViewById(R.id.spinnerSports);
listViewTeams = (ListView) findViewById(R.id.listViewTeams);
textDate = (EditText) findViewById(R.id.textDate);
textTime = (EditText) findViewById(R.id.textTime);
buttonAddTeam = (Button) findViewById(R.id.buttonAddTeam);
teams = new ArrayList<>();
buttonAddTeam.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent myIntent = new Intent(MainActivity.this,
AddActivity.class);
startActivity(myIntent);
}
});
listViewTeams.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
Team team = teams.get(i);
Intent intent = new Intent(getApplicationContext(), ChatRoomActivity.class);
intent.putExtra(TEAM_ID, team.getTeamId());
intent.putExtra(TEAM_NAME, team.getTeamName());
startActivity(intent);
}
});
listViewTeams.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> adapterView, View view, int i, long l) {
Team team = teams.get(i);
showUpdateDeleteDialog(team.getTeamId(), team.getTeamName());
return true;
}
});
}
private void showUpdateDeleteDialog(final String teamId, String teamName) {
AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(this);
LayoutInflater inflater = getLayoutInflater();
final View dialogView = inflater.inflate(R.layout.update_dialog, null);
dialogBuilder.setView(dialogView);
final EditText editTextName = (EditText) dialogView.findViewById(R.id.editTextName);
final Spinner spinnerSport = (Spinner) dialogView.findViewById(R.id.spinnerSports);
final Button buttonUpdate = (Button) dialogView.findViewById(R.id.buttonUpdateTeam);
final Button buttonDelete = (Button) dialogView.findViewById(R.id.buttonDeleteTeam);
final EditText textDate = (EditText) dialogView.findViewById(R.id.textDate);
final EditText textTime = (EditText) dialogView.findViewById(R.id.textTime);
dialogBuilder.setTitle(teamName);
final AlertDialog b = dialogBuilder.create();
b.show();
textDate.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
final Calendar c = Calendar.getInstance();
int mYear = c.get(Calendar.YEAR);
int mMonth = c.get(Calendar.MONTH);
int mDay = c.get(Calendar.DAY_OF_MONTH);
datePickerDialog = new DatePickerDialog(MainActivity.this,
new DatePickerDialog.OnDateSetListener() {
@Override
public void onDateSet(DatePicker view, int year,
int monthOfYear, int dayOfMonth) {
textDate.setText(dayOfMonth + "/"
+ (monthOfYear + 1) + "/" + year);
}
}, mYear, mMonth, mDay);
datePickerDialog.show();
}
});
textTime.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Calendar mcurrentTime = Calendar.getInstance();
int hour = mcurrentTime.get(Calendar.HOUR_OF_DAY);
int minute = mcurrentTime.get(Calendar.MINUTE);
TimePickerDialog mTimePicker;
mTimePicker = new TimePickerDialog(MainActivity.this, new TimePickerDialog.OnTimeSetListener() {
@Override
public void onTimeSet(TimePicker timePicker, int selectedHour, int selectedMinute) {
textTime.setText(selectedHour + ":" + selectedMinute);
}
}, hour, minute, true);
mTimePicker.setTitle("Select Time");
mTimePicker.show();
}
});
buttonUpdate.setOnClickListener(new View.OnClickListener() {
FirebaseUser user = firebaseAuth.getCurrentUser();
@Override
public void onClick(View view) {
String name = editTextName.getText().toString().trim();
String sport = spinnerSport.getSelectedItem().toString();
String owner = user.getUid();
String date = textDate.getText().toString();
String time = textTime.getText().toString();
if (!TextUtils.isEmpty(name)) {
updateTeam(teamId, name, sport, owner, date, time);
b.dismiss();
}
}
});
buttonDelete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
deleteTeam(teamId);
b.dismiss();
}
});
}
private boolean updateTeam(String id, String name, String sport, String owner, String date, String time) {
DatabaseReference dR = FirebaseDatabase.getInstance().getReference("teams").child(id);
Team team = new Team(id, name, sport, owner, date, time);
dR.setValue(team);
Toast.makeText(getApplicationContext(), "Team Updated", Toast.LENGTH_LONG).show();
return true;
}
private boolean deleteTeam(String id) {
DatabaseReference dR = FirebaseDatabase.getInstance().getReference("teams").child(id);
dR.removeValue();
DatabaseReference drTracks = FirebaseDatabase.getInstance().getReference("tracks").child(id);
drTracks.removeValue();
Toast.makeText(getApplicationContext(), "Team Deleted", Toast.LENGTH_LONG).show();
return true;
}
@Override
protected void onStart() {
super.onStart();
databaseTeams.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
teams.clear();
for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
Team team = postSnapshot.getValue(Team.class);
teams.add(team);
}
TeamList teamAdapter = new TeamList(MainActivity.this, teams);
listViewTeams.setAdapter(teamAdapter);
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.action_logout:
firebaseAuth.signOut();
finish();
startActivity(new Intent(this, SignInActivity.class));
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
Logcat:
03-19 01:40:25.709 2995-2995/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.user.stfv2, PID: 2995
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.user.stfv2/com.example.user.stfv2.ChatRoomActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at com.example.user.stfv2.ChatRoomActivity.setUsername(ChatRoomActivity.java:58)
at com.example.user.stfv2.ChatRoomActivity.onCreate(ChatRoomActivity.java:73)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
编辑 1：
layout_chat_room:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
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"
tools:context="com.example.user.stfv2.MainActivity">
<RelativeLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/header"
android:gravity="end">
<ImageView
android:layout_width="36dp"
android:layout_height="36dp"
android:id="@+id/userIcon"
android:foregroundGravity="center"
android:layout_alignParentStart="true"
android:layout_alignParentLeft="true" />
<TextView
android:layout_width="141dp"
android:layout_height="wrap_content"
android:id="@+id/usernameTxt"
android:layout_toRightOf="@+id/userIcon"
android:layout_alignTop="@+id/userIcon"
android:layout_alignBottom="@+id/userIcon"
android:gravity="center_vertical"
tools:text="Username"
android:layout_weight="0" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Sign in"
android:id="@+id/loginBtn"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Sign out"
android:id="@+id/logoutBtn"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true" />
</RelativeLayout>
<android.support.v7.widget.RecyclerView
android:id="@+id/messagesList"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
tools:listitem="@android:layout/two_line_list_item"
android:layout_above="@+id/footer"
android:layout_below="@+id/header" />
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:id="@+id/footer">
<ImageButton
android:layout_width="36dp"
android:layout_height="36dp"
android:id="@+id/imageBtn"
android:background="@android:drawable/ic_menu_gallery" />
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/messageTxt"
android:layout_gravity="bottom"
android:layout_weight="1"
android:inputType="textShortMessage|textAutoCorrect" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Send"
android:id="@+id/sendBtn"
android:layout_gravity="bottom" />
</LinearLayout>
</RelativeLayout>
聊天室活动：
public class ChatRoomActivity extends AppCompatActivity {
private static final String TAG = "ChatRoomActivity";
static final int RC_PHOTO_PICKER = 1;
private Button sendBtn;
private EditText messageTxt;
private RecyclerView messagesList;
private ChatMessageAdapter adapter;
private ImageButton imageBtn;
private TextView usernameTxt;
private View loginBtn;
private View logoutBtn;
private FirebaseApp app;
private FirebaseDatabase database;
private FirebaseAuth auth;
private FirebaseStorage storage;
private DatabaseReference databaseRef;
private StorageReference storageRef;
private String username;
private void setUsername(String username) {
Log.d(TAG, "setUsername("+String.valueOf(username)+")");
if (username == null) {
username = "Android";
}
boolean isLoggedIn = !username.equals("Android");
this.username = username;
this.usernameTxt.setText(username);
this.logoutBtn.setVisibility(isLoggedIn ? View.VISIBLE : View.GONE);
this.loginBtn .setVisibility(isLoggedIn ? View.GONE : View.VISIBLE);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
sendBtn = (Button) findViewById(R.id.sendBtn);
messageTxt = (EditText) findViewById(R.id.messageTxt);
messagesList = (RecyclerView) findViewById(R.id.messagesList);
imageBtn = (ImageButton) findViewById(R.id.imageBtn);
loginBtn = findViewById(R.id.loginBtn);
logoutBtn = findViewById(R.id.logoutBtn);
usernameTxt = (TextView) findViewById(R.id.usernameTxt);
setUsername("Android");
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
messagesList.setHasFixedSize(false);
messagesList.setLayoutManager(layoutManager);
// Show an image picker when the user wants to upload an imasge
imageBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("image/jpeg");
intent.putExtra(Intent.EXTRA_LOCAL_ONLY, true);
startActivityForResult(Intent.createChooser(intent, "Complete action using"), RC_PHOTO_PICKER);
}
});
// Show a popup when the user asks to sign in
loginBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
LoginDialog.showLoginPrompt(ChatRoomActivity.this, app);
}
});
// Allow the user to sign out
logoutBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
auth.signOut();
}
});
adapter = new ChatMessageAdapter(this);
messagesList.setAdapter(adapter);
adapter.registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {
public void onItemRangeInserted(int positionStart, int itemCount) {
messagesList.smoothScrollToPosition(adapter.getItemCount());
}
});
// Get the Firebase app and all primitives we'll use
app = FirebaseApp.getInstance();
database = FirebaseDatabase.getInstance(app);
auth = FirebaseAuth.getInstance(app);
storage = FirebaseStorage.getInstance(app);
// Get a reference to our chat "room" in the database
databaseRef = database.getReference("chat");
sendBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
ChatMessage chat = new ChatMessage(username, messageTxt.getText().toString());
// Push the chat message to the database
databaseRef.push().setValue(chat);
messageTxt.setText("");
}
});
// Listen for when child nodes get added to the collection
databaseRef.addChildEventListener(new ChildEventListener() {
public void onChildAdded(DataSnapshot snapshot, String s) {
// Get the chat message from the snapshot and add it to the UI
ChatMessage chat = snapshot.getValue(ChatMessage.class);
adapter.addMessage(chat);
}
public void onChildChanged(DataSnapshot dataSnapshot, String s) { }
public void onChildRemoved(DataSnapshot dataSnapshot) { }
public void onChildMoved(DataSnapshot dataSnapshot, String s) { }
public void onCancelled(DatabaseError databaseError) { }
});
// When the user has entered credentials in the login dialog
LoginDialog.onCredentials(new OnSuccessListener<LoginDialog.EmailPasswordResult>() {
public void onSuccess(LoginDialog.EmailPasswordResult result) {
// Sign the user in with the email address and password they entered
auth.signInWithEmailAndPassword(result.email, result.password);
}
});
// When the user signs in or out, update the username we keep for them
auth.addAuthStateListener(new FirebaseAuth.AuthStateListener() {
public void onAuthStateChanged(FirebaseAuth firebaseAuth) {
if (firebaseAuth.getCurrentUser() != null) {
// User signed in, set their email address as the user name
setUsername(firebaseAuth.getCurrentUser().getEmail());
}
else {
// User signed out, set a default username
setUsername("Android");
}
}
});
}
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == RC_PHOTO_PICKER && resultCode == RESULT_OK) {
Uri selectedImageUri = data.getData();
// Get a reference to the location where we'll store our photos
storageRef = storage.getReference("chat_photos");
// Get a reference to store file at chat_photos/<FILENAME>
final StorageReference photoRef = storageRef.child(selectedImageUri.getLastPathSegment());
// Upload file to Firebase Storage
photoRef.putFile(selectedImageUri)
.addOnSuccessListener(this, new OnSuccessListener<UploadTask.TaskSnapshot>() {
public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
// When the image has successfully uploaded, we get its download URL
Uri downloadUrl = taskSnapshot.getDownloadUrl();
// Set the download URL to the message box, so that the user can send it to the database
messageTxt.setText(downloadUrl.toString());
}
});
}
}
}
您的问题是您定义了错误的 XML 文件。当您使用 ChatroomActivity 中的代码时，您忘记更改 XML 文件。目前设置为setContentView(R.layout.activity_main)，但应该是setContentView(R.layout.layout_chat_room)。