Question

如何在文本视图项中输出Firebase数据？

我已经有一个Firebase数据库

public class Account extends AppCompatActivity implements View.OnClickListener{
private static final String TAG = "Petcare";
private MyPagerAdapter mMyPagerAdapter;
private ImageButton btn;
private TextView P_name;
private TextView P_address;
private TextView P_number;
private DatabaseReference mDB;
private FirebaseAuth firebaseAuth;
private FirebaseDatabase firebasedatabase;
private FirebaseAuth.AuthStateListener firebaseauthlistener;
private String userId;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_account);
    btn = (ImageButton) findViewById(R.id.account_settings);

    P_name = (TextView) findViewById(R.id.profile_name);
    P_address = (TextView) findViewById(R.id.profile_address);
    P_number = (TextView) findViewById(R.id.profile_number);

    firebaseAuth = FirebaseAuth.getInstance();
    firebasedatabase = FirebaseDatabase.getInstance();
    mDB = firebasedatabase.getReference();
    FirebaseUser user = firebaseAuth.getCurrentUser();
    userId = user.getUid();


    mDB.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            Showdata(dataSnapshot);
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });

}
private void Showdata(DataSnapshot dataSnapshot) {
    for(DataSnapshot ds:dataSnapshot.getChildren()){
    UserInformation uinfo = new UserInformation();
    uinfo.setName(ds.child(userId).getValue(UserInformation.class).getName());
    uinfo.setContact(ds.child(userId).getValue(UserInformation.class).getContact());
    uinfo.setAddress(ds.child(userId).getValue(UserInformation.class).getAddress());

    //display
        P_name.setText(uinfo.getName());
        P_number.setText(uinfo.getContact());
        P_address.setText(uinfo.getAddress());

    }
}
}

我收到错误

null'java.lang.String com.example.jasper.happy_paws.UserInformation.getName（）'为null 对象引用位于 com.example.jasper.happy_paws.Account.Showdata（Account.java:130）

Answer 1

尝试此代码

private void Showdata(DataSnapshot dataSnapshot) {
  P_name.setText(dataSnapshot.child(userId).child("name").getValue());
  P_number.setText(dataSnapshot.child(userId).child("contact").getValue());
  P_address.setText(dataSnapshot.child(userId).child("address").getValue());
}

Answer 2

要解决此问题，请使用以下代码行：

String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference uidRef = rootRef.child("User").child(uid);
ValueEventListener valueEventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        String address = dataSnapshot.child("address").getValue(String.class);
        String contact = dataSnapshot.child("contact").getValue(String.class);
        String name = dataSnapshot.child("name").getValue(String.class);

        P_address.setText(address);
        P_number.setText(contact);
        P_name.setText(name);
    }

    @Override
    public void onCancelled(@NonNull DatabaseError databaseError) {
        Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
    }
};
uidRef.addListenerForSingleValueEvent(valueEventListener);

Answer 3

databaseReference =FirebaseDatabase.getInstance().getReference("databasename"); 

   databaseReference.addListenerForSingleValueEvent(new ValueEventListener(){
        @Override
        public void onDataChange(DataSnapshot dataSnapshot){
            if (dataSnapshot.exists()){
                for (DataSnapshot dataSnapshot1 : dataSnapshot.getChildren()){
              }else{
                  //do something here           
             }}
        @Override
        public void onCancelled(DatabaseError databaseError) {
            Toast.makeText(Allcontact.this, "" + databaseError, 
 Toast.LENGTH_SHORT).show();
        }
    });

如何在文本视图项中输出Firebase数据？

3 个答案: