Here i created an Android program to do what Rob said for firebase beginner(like me)
out there.this program first store the username of the signedUp or signedIn user and then display them in a listView
SignInActivity.java
public class SignInActivity extends BaseActivity implements View.OnClickListener,View.OnKeyListener{
private DatabaseReference mDatabase;
public static FirebaseAuth mAuth;
private static final String TAG = "MainActivity";
EditText usernameField;
EditText passwordField;
TextView changeSignUpModeTextView;
Button signUpButton;
ImageView logo;
RelativeLayout relativeLayout;
Boolean signUpModeActive;
static ArrayList<String> userList = new ArrayList<>();
@Override
public void onStart() {
super.onStart();
// Check auth on Activity start
if (mAuth.getCurrentUser() != null) {
onAuthSuccess(mAuth.getCurrentUser());
}
}
@Override
public boolean onKey(View view, int i, KeyEvent keyEvent) {
if(i == keyEvent.KEYCODE_ENTER && keyEvent.getAction() == keyEvent.ACTION_DOWN){
signUpOrLogIn(view);
}
return false;
}
@Override
public void onClick(View view) {
if(view.getId() == R.id.changeSignUpMode){
if (signUpModeActive == true){
signUpModeActive = false;
changeSignUpModeTextView.setText("Sign Up");
signUpButton.setText("Log In");
}else{
signUpModeActive = true;
changeSignUpModeTextView.setText("Log In");
signUpButton.setText("Sign Up");
}
}else if(view.getId() == R.id.logo || view.getId() == R.id.relativeLayout){
InputMethodManager inm = (InputMethodManager) getSystemService(INPUT_METHOD_SERVICE);
inm.hideSoftInputFromWindow(getCurrentFocus().getWindowToken(),0);
}
}
public void signUpOrLogIn(View view) {
showProgressDialog();
String email = usernameField.getText().toString().trim();
String password = passwordField.getText().toString().trim();
if (signUpModeActive == true) {
mAuth.createUserWithEmailAndPassword(email,password)
.addOnCompleteListener(MainActivity.this, new OnCompleteListener<AuthResult>() {
@Override
public void onComplete(@NonNull Task<AuthResult> task) {
hideProgressDialog();
Toast.makeText(MainActivity.this, "createUserWithEmail:onComplete:" + task.isSuccessful(), Toast.LENGTH_SHORT).show();
// If sign in fails, display a message to the user. If sign in succeeds
// the auth state listener will be notified and logic to handle the
// signed in user can be handled in the listener.
if (!task.isSuccessful()) {
Toast.makeText(MainActivity.this, "Authentication failed." + task.getException().toString().substring(task.getException().toString().indexOf(" ")),
Toast.LENGTH_SHORT).show();
Log.i("Error", task.getException().toString());
} else {
onAuthSuccess(task.getResult().getUser());
showUserList();
}
}
});
} else {
mAuth.signInWithEmailAndPassword(email,password)
.addOnCompleteListener(MainActivity.this, new OnCompleteListener<AuthResult>() {
@Override
public void onComplete(@NonNull Task<AuthResult> task) {
hideProgressDialog();
// If sign in fails, display a message to the user. If sign in succeeds
// the auth state listener will be notified and logic to handle the
// signed in user can be handled in the listener.
if (!task.isSuccessful()) {
// there was an error
Toast.makeText(MainActivity.this, task.getException().toString(),
Toast.LENGTH_LONG).show();
} else
{
onAuthSuccess(task.getResult().getUser());
showUserList();
}
}
});
}
}
public void showUserList(){
startActivity(new Intent(getApplicationContext(), UserList.class));
finish();
}
private void onAuthSuccess(FirebaseUser user) {
String username = usernameFromEmail(user.getEmail());
// Write new user
writeNewUser(user.getUid(), username, user.getEmail());
// Go to MainActivity
}
private String usernameFromEmail(String email) {
if (email.contains("@")) {
return email.split("@")[0];
} else {
return email;
}
}
private void writeNewUser(String userId, String name, String email) {
User user = new User(name, email);
mDatabase.child("users").child(userId).setValue(user);
ArrayList<String> userNames = new ArrayList<>();
userNames.add(name);
mDatabase.child("usernamelist").setValue(userNames);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mAuth = FirebaseAuth.getInstance();
mDatabase = FirebaseDatabase.getInstance().getReference();
if(mAuth.getCurrentUser()!=null){
showUserList();
}
usernameField = (EditText) findViewById(R.id.username);
passwordField = (EditText) findViewById(R.id.password);
changeSignUpModeTextView = (TextView) findViewById(R.id.changeSignUpMode);
signUpButton = (Button) findViewById(R.id.signupbutton);
logo = (ImageView)findViewById(R.id.logo);
relativeLayout= (RelativeLayout)findViewById(R.id.relativeLayout);
signUpModeActive = true;
changeSignUpModeTextView.setOnClickListener(this);
usernameField.setOnKeyListener(this);
passwordField.setOnKeyListener(this);
logo.setOnClickListener(this);
relativeLayout.setOnClickListener(this);
}
}
UserList.java
public class UserList extends AppCompatActivity {
private static final String TAG = "UserList" ;
private DatabaseReference userlistReference;
private ValueEventListener mUserListListener;
ArrayList<String> usernamelist = new ArrayList<>();
ArrayAdapter arrayAdapter;;
ListView userListView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_user_list);
userlistReference = FirebaseDatabase.getInstance().getReference().child("usernamelist");
onStart();
userListView = (ListView) findViewById(R.id.userlistview);
}
@Override
protected void onStart() {
super.onStart();
final ValueEventListener userListener = new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
usernamelist = new ArrayList<>((ArrayList) dataSnapshot.getValue());
usernamelist.remove(usernameOfCurrentUser());
Log.i(TAG, "onDataChange: "+usernamelist.toString());
arrayAdapter = new ArrayAdapter(UserList.this,android.R.layout.simple_list_item_1,usernamelist);
userListView.setAdapter(arrayAdapter);
}
@Override
public void onCancelled(DatabaseError databaseError) {
Log.w(TAG, "onCancelled: ",databaseError.toException());
Toast.makeText(UserList.this, "Failed to load User list.",
Toast.LENGTH_SHORT).show();
}
};
userlistReference.addValueEventListener(userListener);
mUserListListener = userListener;
}
public String usernameOfCurrentUser()
{
String email = MainActivity.mAuth.getCurrentUser().getEmail();
if (email.contains("@")) {
return email.split("@")[0];
} else {
return email;
}
}
@Override
public void onStop() {
super.onStop();
// Remove post value event listener
if (mUserListListener != null) {
userlistReference.removeEventListener(mUserListListener);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()) {
case R.id.action_logout:
FirebaseAuth.getInstance().signOut();
startActivity(new Intent(this, MainActivity.class));
finish();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
