Question

我用来检索数据的代码：

Firebase ref = new Firebase(Config.FIREBASE_URL);
            ref.addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot snapshot) {
                    for (DataSnapshot postSnapshot : snapshot.getChildren()) {
                        //Getting the data from snapshot
                        Person person = postSnapshot.getValue(Person.class);


                        //Adding it to a string
                        String string = "Name: "+person.getName()+"\nAddress: "+person.getAddress()+"\nLatLong: "+person.getflat()+","+person.getflng()+"\nReamaining Distance: "+person.getfdist();

                        //Displaying it on textview
                        textViewPersons.setText(string);
                    }
                }

                @Override
                public void onCancelled(FirebaseError firebaseError) {
                    System.out.println("The read failed: " + firebaseError.getMessage());
                }
            });

这就是我的firebase数据库的样子。问题是使用上面的代码我只能检索第二个用户的数据（Simranjit Singh）。我想检索两个用户。

6MpsYKoVMNfJMvUdE9y2oPZSnxb2addclose
   address: 
    "tintinsharma0001@gmail.com"
   fdist: 
    "31.95893"
   flat: 
    "30.69074016"
   flng: 
    "76.74376851"
   name: 
    "Tintin Sharma"
fxrutNP5uLfoPGIJtTuXAYam5dP
   address: 
    "samsinghsimran@gmail.com"
   fdist: 
    "31.95893"
   flat: 
    "30.69074016"
   flng: 
    "76.74376851"
   name: 
    "Simranjit Singh"

Answer 1

问题在于您获取每个用户，并将其分配到相同的文本视图，这会覆盖最后一个人。所以无论你有多少，你都会得到最后一个用户。您应该将用户放入ArrayList或类似的数据结构中，并使用它来填充列表视图：

Firebase ref = new Firebase(Config.FIREBASE_URL);
            ref.addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot snapshot) {
                    ArrayList<Person> peopleList = new ArrayList<Person>():
                    for (DataSnapshot postSnapshot : snapshot.getChildren()) {
                        //Getting the data from snapshot
                        Person person = postSnapshot.getValue(Person.class);

                        //add person to your list
                        peopleList.add(person);
                        //create a list view, and add the apapter, passing in your list

                    }
                   yourListView.setAdapter(personList);
                }

                @Override
                public void onCancelled(FirebaseError firebaseError) {
                    System.out.println("The read failed: " + firebaseError.getMessage());
                }
            });

Answer 2

您没有正确检索数据...您正在覆盖字符串变量中的数据，因此您只能获得第二个值。您需要一个用户列表。

    private static HashMap<String, Person> personList = new HashMap<>();;
    Firebase ref = new Firebase(Config.FIREBASE_URL);
                ref.addValueEventListener(new ValueEventListener() {
                    @Override
                    public void onDataChange(DataSnapshot snapshot) {
                        for (DataSnapshot postSnapshot : snapshot.getChildren()) {
                            //Getting the data from snapshot
                            Person person = postSnapshot.getValue(Person.class);
    personList.put(snapshot.getKey(), person.getName());


                            //Adding it to a string
                            String string = "Name: "+person.getName()+"\nAddress: "+person.getAddress()+"\nLatLong: "+person.getflat()+","+person.getflng()+"\nReamaining Distance: "+person.getfdist();

                            //Displaying it on textview
                            textViewPersons.setText(string);
                        }
//Return you personList here
                    }

                    @Override
                    public void onCancelled(FirebaseError firebaseError) {
                        System.out.println("The read failed: " + firebaseError.getMessage());
                    }
                });

如何在Firebase（android）中检索所有用户数据？

2 个答案: