I have included a chatting feature in my app using Firebase realtime Database. I want to be able to show notification when another user sends a message even when the app is turned but I'm not sure how
package com.example.android.crazytenmessenger;
import androidx.activity.result.ActivityResultCallback;
import androidx.activity.result.ActivityResultLauncher;
import androidx.activity.result.contract.ActivityResultContracts;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.net.Uri;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.text.Editable;
import android.text.InputFilter;
import android.text.TextWatcher;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.Toast;
import com.example.android.crazytenmessenger.auth.UserProfileActivity;
import com.example.android.crazytenmessenger.dao.MessageDAOHelper;
import com.example.android.crazytenmessenger.utils.DateUtils;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.android.gms.tasks.Task;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.snackbar.BaseTransientBottomBar;
import com.google.android.material.snackbar.Snackbar;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.ChildEventListener;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.storage.FirebaseStorage;
import com.google.firebase.storage.OnProgressListener;
import com.google.firebase.storage.StorageReference;
import com.google.firebase.storage.UploadTask;
import java.util.ArrayList;
import java.util.List;
public class MessagingActivity extends AppCompatActivity {
private ListView listView;
private FloatingActionButton sendButton;
private EditText messageEditTextBox;
private ProgressBar progressBar;
private ImageView imagePicker;
private static final String TAG=MessagingActivity.class.getSimpleName();
private static final int MAX_WORD_LIMIT = 1000;
private DatabaseReference messageDatabaseReference;
private FirebaseStorage firebaseStorage;
private StorageReference chatPhotoStorageReference;
private ChildEventListener childEventListener;
private List<Message> messages;
private SharedPreferences sharedPreferences;
private String username;
private MessageDAOHelper daoHelper;
private MessageAdapter messageAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_messaging);
listView=(ListView) findViewById(R.id.message_list_view);
messageEditTextBox=(EditText) findViewById(R.id.message_box);
sendButton=(FloatingActionButton) findViewById(R.id.send_button);
imagePicker=(ImageView) findViewById(R.id.image_picker);
progressBar=(ProgressBar) findViewById(R.id.progress_Bar);
daoHelper=new MessageDAOHelper();
messageDatabaseReference=daoHelper.getMessageDatabaseReference();
firebaseStorage=FirebaseStorage.getInstance();
chatPhotoStorageReference=firebaseStorage.getReference().child("chat_photos");
sharedPreferences= PreferenceManager.getDefaultSharedPreferences(this);
messages=new ArrayList<>();
loadPreviousMessages();
messageAdapter=new MessageAdapter(this,R.layout.item_message,messages);
listView.setAdapter(messageAdapter);
username=FirebaseAuth.getInstance().getCurrentUser().getDisplayName();
ActivityResultLauncher<String> mGetContent=registerForActivityResult(new ActivityResultContracts.GetContent(),
new ActivityResultCallback<Uri>() {
@Override
public void onActivityResult(Uri result) {
uploadPhoto(result);
}
});
childEventListener=new ChildEventListener() {
@Override
public void onChildAdded(@NonNull DataSnapshot snapshot, @Nullable String previousChildName) {
Message currentMsg=snapshot.getValue(Message.class);
messageAdapter.add(currentMsg);
listView.smoothScrollToPosition(messageAdapter.getCount());
}
@Override
public void onChildChanged(@NonNull DataSnapshot snapshot, @Nullable String previousChildName) { }
@Override
public void onChildRemoved(@NonNull DataSnapshot snapshot) {
Snackbar.make(findViewById(android.R.id.content),"succesfully removed", BaseTransientBottomBar.LENGTH_SHORT).show();
Log.v(TAG,"Removed : "+snapshot.getValue());
}
@Override
public void onChildMoved(@NonNull DataSnapshot snapshot, @Nullable String previousChildName) { }
@Override
public void onCancelled(@NonNull DatabaseError error) { }
};
messageEditTextBox.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) { }
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
if(s.toString().trim().length()>0)
sendButton.setEnabled(true);
else
sendButton.setEnabled(false);
}
@Override
public void afterTextChanged(Editable s) { }
});
messageEditTextBox.setFilters(new InputFilter[]{new InputFilter.LengthFilter(MAX_WORD_LIMIT)});
sendButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
username=sharedPreferences.getString(getString(R.string.my_profile_username_key),"USER");
username=FirebaseAuth.getInstance().getCurrentUser().getDisplayName();
String timeStamp= DateUtils.getCurrentTimestamp();
Message message=new Message(messageEditTextBox.getText().toString(),username, null, timeStamp);
daoHelper.addMessage(message).addOnSuccessListener(new OnSuccessListener<Void>() {
@Override
public void onSuccess(Void unused) {
}
}).addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
Snackbar.make(findViewById(android.R.id.content),"Message Not Sent "+e.getMessage(), BaseTransientBottomBar.LENGTH_SHORT).show();
}
});
messageEditTextBox.setText("");
}
});
imagePicker.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mGetContent.launch("image/*");
}
});
messageDatabaseReference.addChildEventListener(childEventListener);
}
/**
* Signing in the the current user automatically using OnStart
* Using Firebase Auth getCurrentUser
*/
@Override
protected void onStart() {
super.onStart();
String user= FirebaseAuth.getInstance().getCurrentUser().getDisplayName();
if(user==null)
user="";
Snackbar.make(findViewById(android.R.id.content),"Welcome "+user,BaseTransientBottomBar.LENGTH_SHORT).show();
}
public void uploadPhoto(Uri uri){
final ProgressDialog progressDialog=new ProgressDialog(this);
progressDialog.setTitle("Uploading Image.....");
progressDialog.show();
StorageReference photoRef=chatPhotoStorageReference.child(uri.getLastPathSegment());
photoRef.putFile(uri)
.addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
@Override
public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
Task<Uri> result=taskSnapshot.getMetadata().getReference().getDownloadUrl();
progressDialog.dismiss();
result.addOnSuccessListener(new OnSuccessListener<Uri>() {
@Override
public void onSuccess(Uri uri) {
String timeStamp=DateUtils.getCurrentTimestamp();
Message newMessage=new Message(null,username,uri.toString(), timeStamp);
daoHelper.addMessage(newMessage);
}
});
}
})
.addOnProgressListener(new OnProgressListener<UploadTask.TaskSnapshot>() {
@Override
public void onProgress(@NonNull UploadTask.TaskSnapshot snapshot) {
double percentage=(100.00*snapshot.getBytesTransferred() / snapshot.getTotalByteCount());
Log.v(TAG,"Progress : "+percentage);
progressDialog.setMessage("Progress : "+(int)percentage+"%");
}
});
Toast.makeText(this,"Image uploaded",Toast.LENGTH_SHORT).show();
}
private void deleteAllMessages(){
AlertDialog dialog=new AlertDialog.Builder(this)
.setTitle("Delete all messages")
.setMessage("Are you sure you want to delete all messages")
.setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
Toast.makeText(getApplicationContext(),"Deleting... ",Toast.LENGTH_SHORT).show();
messageDatabaseReference.removeValue().addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task) {
}
});
chatPhotoStorageReference.delete().addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task) {
Toast.makeText(getApplicationContext(),"All files Deleted ",Toast.LENGTH_SHORT).show();
messages.clear();
messageAdapter.notifyDataSetChanged();
listView.setAdapter(messageAdapter);
loadPreviousMessages();
}
});
}
})
.setNegativeButton(android.R.string.no,null)
.setIcon(android.R.drawable.ic_dialog_alert)
.show();
}
private void loadPreviousMessages(){
messageDatabaseReference.get().addOnCompleteListener(new OnCompleteListener<DataSnapshot>() {
@Override
public void onComplete(@NonNull Task<DataSnapshot> task) {
if(!task.isSuccessful())
Log.e(TAG,"Error in retrieving data ",task.getException());
else{
int count= (int) task.getResult().getChildrenCount();
if(count==0){
Snackbar.make(findViewById(android.R.id.content),
"Let's start chatting",
BaseTransientBottomBar.LENGTH_SHORT).show();
progressBar.setVisibility(View.GONE);
return;
}
progressBar.setVisibility(View.GONE);
}
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main_menu,menu);
return true;
}
@Override
public boolean onOptionsItemSelected(@NonNull MenuItem item) {
int id=item.getItemId();
if(id==R.id.profile_menu){
Intent intent=new Intent(MessagingActivity.this, UserProfileActivity.class);
startActivity(intent);
}else if(id==R.id.delete_all_option){
deleteAllMessages();
}else if(id==R.id.signout){
signoutCurrentUser();
}
return super.onOptionsItemSelected(item);
}
private void signoutCurrentUser() {
FirebaseAuth.getInstance().signOut();
finish();
}
}
I used child event listeners on firebase database reference to know the message sent but how to use it for notification.
