Question

我有一个应用程序正在检查存储在Firebase数据库中的兴趣点。每个用户都有自己对流派的特定兴趣，这会影响地图上显示的内容。

为了分析每个用户的这些兴趣，我从数据库中获取他们的兴趣并将它们放在特定于用户的散列图中。在用户的构造函数中，我调用了setInterests（）方法，该方法实际上在HashMap中执行数据设置。

我还在User类中有一个方法，用于检查用户interestMap的特定genreID的内容。如果他们拥有它，则返回true，如果他们没有，则返回false。我还检查hashmap是否为空，如果是，我想显示所有数据。但是，当调用hasInterest()方法时，尚未设置用户的interestMap。在User构造函数中调用setInterets()，用户实例在我MapActivity的onCreate中创建。

用户构造函数

public User(String username){
    this.username = username;
    interestMap = new HashMap<>();
    setInterests();
}

有兴趣方法

// Check if the user has the listed interest
public boolean hasInterest(final long genreId){
    String id = String.valueOf(genreId);

    System.out.println("Has Interest: " + interestMap);
    // If the user has no interests, display the listed interest
    if(interestMap.isEmpty()){
        Log.d(TAG, "User has  no interests, showing all " + interestMap.get(id));
        return true;
    }

    Object interest =  interestMap.get(id);
    // If the user does not have the listed interest, don't display it
    if(interest == null){
        Log.d(TAG, "User does not have interest in this, not showing data");
        return false;
    }
    Log.d(TAG, "User has interest in Genre"+ interestMap.get(id)+ ", showing data");
    return true;
}

设置兴趣方法

 public void setInterests() throws DatabaseException{

    mDatabase = FirebaseDatabase.getInstance().getReference("users/" + getUid()+"/interests");
    try{
        mDatabase.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                for(DataSnapshot interestSnapshot: dataSnapshot.getChildren()){
                    String interestKey = interestSnapshot.getKey();
                    Object interestValue = interestSnapshot.getValue();

                    Log.d(TAG, "Key = " + interestKey + "; Value = " + interestValue);
                    push(interestKey, interestValue);
                }
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {
                Log.w(TAG, "Could not access data: ", databaseError.toException());
                Log.d(TAG, "Error Code: " + databaseError.getCode());
            }
        });
    }catch(DatabaseException e){
        Log.w(TAG, "Database Exception " + e);
    }
    System.out.println(interestMap);
}

在创建方法上映射活动

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_maps);

    if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        checkLocationPermission();
    }
    // Obtain the SupportMapFragment and get notified when the map is ready to be used.
    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);

    Firebase.setAndroidContext(this);

    auth = FirebaseAuth.getInstance();
    user = new User(auth.getCurrentUser().getEmail());

在Maps OnLocationChanged

中调用Has Interest方法

ref.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            Log.d(TAG, "Inside onDataChange");
            for (final DataSnapshot poiSnapshot : dataSnapshot.getChildren()) {

                final String mPoiSnapshot = poiSnapshot.getKey();
                // Get data from Firebase
                final String mPoiTitle = (String) poiSnapshot.child("title").getValue();
                final String mPoiStory = (String) poiSnapshot.child("story").getValue();
                final long mPoiGenreID = (long) poiSnapshot.child("Genre/ID").getValue();
                final String mPoiGenreType= (String) poiSnapshot.child("Genre/Type").getValue();

                final POIGenre mPoiGenre = new POIGenre(mPoiGenreID, mPoiGenreType);

                if(user.hasInterest(mPoiGenreID)) {

出于某种原因，在实际创建用户之前调用此hasInterest()。我尝试在OnLocationChanged方法中创建我的用户，其中实际调用hasInterest()作为调试方法，但这并没有影响任何事情。

这是我的调试，我打印出interestMap的内容以及hasInterest()方法检查时的内容。

 I/System.out: Has Interest: {}
 D/******* USER user@user.com: User has  no interests, showing all null
 I/System.out: Has Interest: {} 
 D/******* USER user@user.com: User has  no interests, showing all null
 I/System.out: Has Interest: {}
 D/******* USER user@user.com: User has  no interests, showing all null
 I/System.out: Has Interest: {}
 D/******* USER user@user.com: User has  no interests, showing all null
 D/******* USER user@user.com: Key = 1; Value = Historical
 I/System.out: {1=Historical}

最后，您可以看到我的Firebase中的历史类型被放置在interestMap

中

我只是错过了一些痛苦明显的东西吗？任何帮助都会受到大力赞赏。

Android在数据实际放入hashmap之前检查hashmap是否有数据

0 个答案: