Question

嘿，我试图从fire base实时数据库中检索数据，但是当我打开活动时，ListView没有显示任何内容。

我做了我在YouTube和FireBase官方网站上缝的所有东西，但不起作用谢谢帮手

主要代码：

public class HomePage extends AppCompatActivity  {
TextView tvBalance ;
ListView lvExpense ;
ArrayList <Expense> arrayList ;
expenseAdapter expenseAdapter ;
private DatabaseReference database ;
FirebaseAuth firebaseAuth;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home_page);

    firebaseAuth = FirebaseAuth.getInstance();
    // Find view by id
    tvBalance = (TextView) findViewById(R.id.tvBalance) ;
    lvExpense = (ListView) findViewById(R.id.lvExpense) ;
    // Reference

   retriveData() ;
}
public void retriveData ()
{
    database = FirebaseDatabase.getInstance().getReference("Expense") ;
    database.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            arrayList = new ArrayList <Expense> ();
            for( DataSnapshot data : dataSnapshot.getChildren() )
            {

                Expense p = data.getValue(Expense.class);
                arrayList.add(p);
            }

            expenseAdapter = new expenseAdapter(HomePage.this, 0,0 ,arrayList) ;
            lvExpense.setAdapter(expenseAdapter);
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {
            Toast.makeText(HomePage.this, databaseError.getMessage() ,Toast.LENGTH_SHORT).show();

        }
    }) ;
}

}

适配器代码

public class expenseAdapter extends ArrayAdapter <Expense> {

Context context;
List <Expense> objects;

public expenseAdapter(Context context, int resource, int textViewResourceId, List<Expense> objects) {
    super(context, resource, textViewResourceId, objects);

    this.context=context;
    this.objects=objects;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {

    LayoutInflater layoutInflater = ((Activity)context).getLayoutInflater();
    View view = layoutInflater.inflate(R.layout.expense_listview, parent, true);

    TextView tvTitle = (TextView)view.findViewById(R.id.tvTitle);
    TextView tvCategory = (TextView)view.findViewById(R.id.tvCategory);
    TextView tvDate = (TextView)view.findViewById(R.id.tvDate);
    TextView tvPrice = (TextView)view.findViewById(R.id.tvPrice);
    Expense temp = objects.get(position);
    tvTitle.setText(temp.getTitle());
    tvCategory.setText(temp.getCategory());
    tvDate.setText(temp.getDay() + "/" + temp.getMonth() + "/" + temp.getYear());
    tvPrice.setText(Double.toString(temp.getMoney()));
    return view ;
}

}

当我运行该应用程序时，所有内容都会出现，但它只是忽略了检索数据的功能。没有错误或类似的东西，但看起来它根本没有作用

从FireBase实时数据库中检索数据

0 个答案: