如何从Firebase Android检索部分数据
接触碎片如何从Firebase Android检索部分数据,android,database,firebase,firebase-realtime-database,fetch,Android,Database,Firebase,Firebase Realtime Database,Fetch,接触碎片 ListView usersList; TextView noUsersText; ArrayList<String> al = new ArrayList<>(); int totalUsers = 0; ProgressDialog mProgressDialogue; @Override public View onCreateView(LayoutInflater inflater, ViewGroup container,
ListView usersList;
TextView noUsersText;
ArrayList<String> al = new ArrayList<>();
int totalUsers = 0;
ProgressDialog mProgressDialogue;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_contacts, container, false);
usersList = (ListView)rootView.findViewById(R.id.usersList);
noUsersText = (TextView)rootView.findViewById(R.id.noUsersText);
mProgressDialogue = new ProgressDialog(getActivity());
mProgressDialogue.setMessage("Loading...");
mProgressDialogue.show();
String url = "https://messageplus-cd647.firebaseio.com/Users.json";
StringRequest request = new StringRequest(Request.Method.GET, url, new Response.Listener<String>(){
@Override
public void onResponse(String s) {
doOnSuccess(s);
}
},new Response.ErrorListener(){
@Override
public void onErrorResponse(VolleyError volleyError) {
System.out.println("" + volleyError);
}
});
RequestQueue rQueue = Volley.newRequestQueue(getActivity());
rQueue.add(request);
usersList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
UserDetails.chatWith = al.get(position);
Intent intent = new Intent(getActivity(), Chat.class);
startActivity(intent);
}
});
return rootView;
}
ListView用户列表;
文本视图nouser文本;
ArrayList al=新的ArrayList();
int totalUsers=0;
进程对话;进程对话;
@凌驾
创建视图上的公共视图(布局、充气机、视图组容器、,
Bundle savedInstanceState){
视图根视图=充气机。充气(R.layout.fragment\u触点,容器,假);
usersList=(ListView)rootView.findViewById(R.id.usersList);
noUsersText=(TextView)rootView.findViewById(R.id.noUsersText);
mProgressDialogue=newprogressDialog(getActivity());
设置消息(“加载…”);
mProgressDialogue.show();
字符串url=”https://messageplus-cd647.firebaseio.com/Users.json";
StringRequest=newStringRequest(request.Method.GET,url,new Response.Listener()){
@凌驾
公共void onResponse(字符串s){
最终成功;
}
},new Response.ErrorListener(){
@凌驾
公共错误响应(截击错误截击错误){
System.out.println(““+截击错误”);
}
});
RequestQueue rQueue=Volley.newRequestQueue(getActivity());
rQueue.add(请求);
usersList.setOnItemClickListener(新的AdapterView.OnItemClickListener(){
@凌驾
public void onItemClick(AdapterView父对象、视图、整型位置、长id){
UserDetails.chatWith=al.get(位置);
Intent Intent=新的Intent(getActivity(),Chat.class);
星触觉(意向);
}
});
返回rootView;
}
doOnSuccess方法
public void doOnSuccess(String s){
try {
JSONObject obj = new JSONObject(s);
Iterator i = obj.keys();
String key = "";
while(i.hasNext()){
key = i.next().toString();
if(!key.equals(UserDetails.phonenumber)) {
al.add(key);
}
totalUsers++;
}
} catch (JSONException e) {
e.printStackTrace();
}
if(totalUsers <=1){
noUsersText.setVisibility(View.VISIBLE);
usersList.setVisibility(View.GONE);
}
else{
noUsersText.setVisibility(View.GONE);
usersList.setVisibility(View.VISIBLE);
usersList.setAdapter(new ArrayAdapter<String>(getActivity().getApplicationContext(),
android.R.layout.simple_list_item_1 , al));
}
mProgressDialogue.dismiss();
}
public void doOnSuccess(字符串s){
试一试{
JSONObject obj=新的JSONObject;
迭代器i=obj.keys();
字符串键=”;
while(i.hasNext()){
key=i.next().toString();
如果(!key.equals(UserDetails.phonenumber)){
al.添加(键);
}
totalUsers++;
}
}捕获(JSONException e){
e、 printStackTrace();
}
如果(totalUsers要查询Firebase数据库,您只需创建一个数据库引用
,请连接一个侦听器,并像下面这样迭代DataSnapshot
对象:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference usersRef = rootRef.child("Users");
ValueEventListener eventListener = new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
ArrayList<String> arrayList = new ArrayList<>();
ListView listView = (ListView) findViewById(R.id.list_view);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, android.R.id.text1, arrayList);
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String name = ds.child("Name").getValue(String.class);
arrayList.add(name);
}
listView.setAdapter(adapter);
}
@Override
public void onCancelled(DatabaseError databaseError) {}
};
usersRef.addListenerForSingleValueEvent(eventListener);
DatabaseReference rootRef=FirebaseDatabase.getInstance().getReference();
DatabaseReference usersRef=rootRef.child(“用户”);
ValueEventListener eventListener=新的ValueEventListener(){
@凌驾
公共void onDataChange(DataSnapshot DataSnapshot){
ArrayList ArrayList=新的ArrayList();
ListView ListView=(ListView)findViewById(R.id.list\u视图);
ArrayAdapter=新的ArrayAdapter(getApplicationContext(),android.R.layout.simple_list_item_1,android.R.id.text1,arrayList);
对于(DataSnapshot ds:DataSnapshot.getChildren()){
String name=ds.child(“name”).getValue(String.class);
arrayList.add(名称);
}
setAdapter(适配器);
}
@凌驾
已取消的公共void(DatabaseError DatabaseError){}
};
usersRef.addListenerForSingleValueEvent(eventListener);
输出将仅为用户的名称。我可以获取在列表视图而不是日志中显示它的代码吗?无法解析构造函数的ArrayAdapter(anonymous com.google.firebase.database.ValueEventListener,int,int,java.util.ArrayList)更改this
与getApplicationContext()
。查看我的最新答案。它有效吗?但它是getActivity…因为我使用的是一个片段…无论如何,非常感谢你和我一起分享…干杯