我試圖通過在 if 語句中調用函數 checkifUsernameExists(username) 來檢查數據庫中是否存在用戶名。問題是 firebase 的內置函數稱為 public void onDataChange(@NonNull DataSnapshot dataSnapshot)不能返回布爾值。我能做什么？ mCreateBtn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { String username = musername.getText().toString(); String email = mEmail.getText().toString(); String password = mPassword.getText().toString(); if (TextUtils.isEmpty(username) || TextUtils.isEmpty(email) || TextUtils.isEmpty(password)) { Toast.makeText(registerActivity.this, "Cannot sign you in. Please check the form and try again", Toast.LENGTH_SHORT).show(); } else if (password.length() < 6) { Toast.makeText(registerActivity.this, "Password must be at least 6 characters",Toast.LENGTH_LONG).show(); } else if (email_exists == true) { Toast.makeText(registerActivity.this, "Email already exists",Toast.LENGTH_LONG).show(); } else if (checkifUsernameExists(username)) { Toast.makeText(registerActivity.this, "Username already exists", Toast.LENGTH_LONG).show(); } else { message.setTitle("Registering user"); message.setMessage("Pleases wait while we create your account"); message.setCanceledOnTouchOutside(false); message.show(); //registerUser(username, email, password); } } });}
1 回答
蕭十郎
TA貢獻1815條經驗 獲得超13個贊
如果數據庫中不存在用戶名，則使 checkifUsernameExists() 方法無效并在其中調用 registerUser() 方法。
mCreateBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String username = musername.getText().toString();
String email = mEmail.getText().toString();
String password = mPassword.getText().toString();
if (TextUtils.isEmpty(username) || TextUtils.isEmpty(email) || TextUtils.isEmpty(password)) {
Toast.makeText(registerActivity.this, "Cannot sign you in. Please check the form and try again",
Toast.LENGTH_SHORT).show();
} else if (password.length() < 6) {
Toast.makeText(registerActivity.this, "Password must be at least 6 characters",Toast.LENGTH_LONG).show();
} else if (email_exists == true) {
Toast.makeText(registerActivity.this, "Email already exists",Toast.LENGTH_LONG).show();
} else {
checkifUsernameExists(username, email, password);
}
}
});
private void checkifUsernameExists(final String username, final String email, final String password) {
Query usernameQuery = FirebaseDatabase.getInstance().getReference().child("users").orderByChild("username").equalTo(username);
usernameQuery.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
// the username is already in the database
Toast.makeText(registerActivity.this, "Username already exists", Toast.LENGTH_LONG).show();
}else {
message.setTitle("Registering user");
message.setMessage("Pleases wait while we create your account");
message.setCanceledOnTouchOutside(false);
message.show();
registerUser(username, email, password);
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
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