Question

我已经创建了此数据库enter image description here，并希望显示专门针对子级可用性的列表：“可用”项。通过此代码，我几乎达到了目标

public class Homeuser extends AppCompatActivity {

SharedPreferences preferences;
SharedPreferences.Editor editor;
ListView lv;

FirebaseListAdapter adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_homeuser);

    final Vibrator vibeuser = (Vibrator) Homeuser.this.getSystemService(Context.VIBRATOR_SERVICE);

    preferences = PreferenceManager.getDefaultSharedPreferences(this);
    editor = preferences.edit();

    Query query = FirebaseDatabase.getInstance().getReference().child("food");
    lv = findViewById(R.id.list_item);
    FirebaseListOptions<food> options = new FirebaseListOptions.Builder<food>()
            .setLayout(R.layout.list_items).setLifecycleOwner(Homeuser.this)
            .setQuery(query,food.class).build();

    adapter = new FirebaseListAdapter(options)
    {
        @Override
        protected void populateView(View v, Object model, int position) {
            TextView itemname, itemprice, avail;

            itemname = v.findViewById(R.id.itemname);
            itemprice = v.findViewById(R.id.itemprice);
            avail = v.findViewById(R.id.avail);

            food itemFood = (food) model;

            if(itemFood.getAvailability().toString().equals("Available")){
            itemname.setText(itemFood.getFooditemname().toString());
            itemprice.setText(itemFood.getFooditemprice().toString());
            avail.setText(itemFood.getAvailability().toString());}
        }

    };}}

但是面临这样的问题：

enter image description here如何摆脱这种情况？谢谢。

Answer 1

如果您要过滤Firebase数据库记录，则应在whereEqual()方法内使用查询以及populateView()调用和不 if语句。因此，要解决此问题，请更改以下代码行：

Query query = FirebaseDatabase.getInstance().getReference().child("food");

到

Query query = FirebaseDatabase.getInstance().getReference()
    .child("food")
    .orderByChild("availability")
    .equalTo("Available");

并删除if语句。

这是否可能只显示实时Firebase数据库的某些特定子值的列表视图

1 个答案: