Java 这是否可能仅显示实时Firebase数据库的某些特定子值的列表视图
我已经创建了这个数据库,并希望显示专门针对子可用性的列表:“可用”项。通过这段代码,我几乎达到了目标Java 这是否可能仅显示实时Firebase数据库的某些特定子值的列表视图,java,android,firebase,firebase-realtime-database,Java,Android,Firebase,Firebase Realtime Database,我已经创建了这个数据库,并希望显示专门针对子可用性的列表:“可用”项。通过这段代码,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
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());}
}
};}}
公共类Homeuser扩展AppCompative活动{
共享参考偏好;
SharedReferences.Editor;
ListView lv;
FirebaseListAdapter;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity\u homeuser);
最终可控震源vibeuser=(可控震源)Homeuser.this.getSystemService(Context.可控震源\u服务);
preferences=PreferenceManager.getDefaultSharedPreferences(此);
editor=preferences.edit();
Query Query=FirebaseDatabase.getInstance().getReference().child(“食物”);
lv=findViewById(R.id.list\U项);
FirebaseListOptions=new FirebaseListOptions.Builder()
.setLayout(R.layout.list_项).setLifecycleOwner(Homeuser.this)
.setQuery(query,food.class).build();
适配器=新FirebaseListAdapter(选项)
{
@凌驾
受保护的void populateView(视图v、对象模型、int位置){
text查看项目名称、项目价格、效用;
itemname=v.findviewbyd(R.id.itemname);
itemprice=v.findViewById(R.id.itemprice);
avail=v.findViewById(R.id.avail);
食品项目食品=(食品)模型;
if(itemFood.getAvailability().toString().equals(“Available”)){
itemname.setText(itemFood.getFooditemname().toString());
itemprice.setText(itemFood.getFooditemprice().toString());
avail.setText(itemFood.getAvailability().toString());}
}
};}}
但面临这样一个问题:
如何摆脱这个?谢谢。如果要筛选Firebase数据库记录,应在
populateView()
方法中使用查询以及whereEqual()
调用和notIf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
然后删除if语句。您要删除的元素是什么?@AlexMamo列表视图包含我不想在此活动中显示的空行(状态为“不可用”)。我现在明白了,我现在给您写一个答案。
Query query = FirebaseDatabase.getInstance().getReference()
.child("food")
.orderByChild("availability")
.equalTo("Available");