在android中使用firebase数据填充ListView

我又回到这个问题上来了，虽然我很接近：我有下面的代码，我试图在列表视图中显示firebase值

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_mystatement);
        listview = (ListView) findViewById(R.id.listview);
        textView4 = (TextView) findViewById(R.id.textView4);
        adapter = new ArrayAdapter<String>(this, android.R.layout.simple_dropdown_item_1line, list);
        listview.setAdapter(adapter);
        dref = FirebaseDatabase.getInstance().getReference();


        DatabaseReference dref = FirebaseDatabase.getInstance().getReference();
        dref= dref.child("Expenditure");

        dref.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot snapshot) {
                for (DataSnapshot postSnapshot : snapshot.getChildren()) {
                    //Getting the data from snapshot
                    DogExpenditure dogExpenditure = postSnapshot.getValue(DogExpenditure.class);

                    //Adding it to a string
                    String expenses = "Amount: "+dogExpenditure.getAmount()+"\nReason for Use: "+dogExpenditure.getItem()+"\n\n";

                    String amount = dogExpenditure.getAmount();
                    String item = dogExpenditure.getItem();

                    System.out.println(expenses);


                }
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }


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

---

有人能告诉我如何在我的应用程序中显示该输出吗，因为目前它没有显示任何内容，但在调试控制台中我可以看到它

生成dref的单例对象

---

列表尚未初始化。

您应该将您的费用添加到列表中，并使用
adapter.notifyDataSetChanged（）

列表.添加（费用）

adapter.notifyDataSetChanged（）

//就在onCreate上面
List expenseList=new ArrayList（）；
阵列适配器；
//值内事件侦听器
expenseList.add（费用）
if（expensList.size（）=1）
{
adapter=newarrayadapter（getApplicationContext（），android.R.layout.simple\u list\u item\u 1，expensList）；
setAdapter（适配器）
}
else if（expenseList.size（）>1）
{
adapter.notifyDatasetChanged（）；
}

您可以使用

用firebase数据填充listView非常简单

只需添加依赖项即可：

连接到Firebase

创建自定义FirebaseListAdapter子类

比如：

  listview = (ListView) findViewById(R.id.listview);
    DatabaseReference dref = FirebaseDatabase.getInstance().getReference();
    mAdapter = new FirebaseListAdapter<DogExpenditure>(this, DogExpenditure.class, R.layout.yourLayout, ref) {
            @Override
            protected void populateView(View view, DogExpenditure myObj, int position) {
               //populate your view
               String amount = dogExpenditure.getAmount()
               //Put the value in your layout.
            }
        };
listview.setAdapter(mAdapter);

listview=（listview）findViewById（R.id.listview）；
DatabaseReference dref=FirebaseDatabase.getInstance（）.getReference（）；
mAdapter=新的FirebaseListAdapter（this，dogExpression.class，R.layout.yourLayout，ref）{
@凌驾
受保护的void populateView（视图视图、dogbj、int位置）{
//填充您的视图
字符串金额=支出。getAmount（）
//将值放入布局中。
}
};
setAdapter（mAdapter）；

---

更多信息。

首先创建一个适配器，因为您已经拥有model类。 MyAdapter.java

 public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {

private Context context;
private List<DogExpenditure> uploads;

public MyAdapter(Context context, List<DogExpenditure> uploads) {
    this.uploads = uploads;
    this.context = context;
}

@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.layout_firebase_images, parent, false);
    ViewHolder viewHolder = new ViewHolder(v);
    return viewHolder;
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
    DogExpenditure upload = uploads.get(position);

    holder.textViewName.setText(upload.getAmount());
    holder.textView1.setText(upload.getYourData());

}

@Override
public int getItemCount() {

    return uploads.size();
}

class ViewHolder extends RecyclerView.ViewHolder {

    public TextView textViewName;
    public ImageView imageView;

    public ViewHolder(View itemView) {
        super(itemView);

        textViewName = (TextView) itemView.findViewById(R.id.textViewName);
        textview1 = (TextView) itemView.findViewById(R.id.your_id);
    }
}
 }

公共类MyAdapter扩展了RecyclerView.Adapter{ 私人语境； 私人名单上传； 公共MyAdapter（上下文、列表上载）{ this.uploads=上传； this.context=上下文； } @凌驾 public ViewHolder onCreateViewHolder（视图组父级，int-viewType）{ 视图v=LayoutInflater.from（parent.getContext（）） .充气（R.layout.layout\u firebase\u图像，父级，假）； 视窗夹持器视窗夹持器=新视窗夹持器（v）； 返回视图持有者； } @凌驾 公共无效onBindViewHolder（ViewHolder，int位置）{ 上传=上传。获取（位置）； holder.textViewName.setText（upload.getAmount（））； holder.textView1.setText（upload.getYourData（））； } @凌驾 public int getItemCount（）{ 返回uploads.size（）； } 类ViewHolder扩展了RecyclerView.ViewHolder{ 公共文本视图文本视图名称； 公共影像视图； 公共视图持有者（视图项视图）{ 超级（项目视图）； textViewName=（TextView）itemView.findViewById（R.id.textViewName）； textview1=（TextView）itemView.findViewById（R.id.your_id）； } } } 现在进入你的活动

private List<DogExpenditure> uploads;
MyAdapter adapter;
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_mystatement);
    listview = (ListView) findViewById(R.id.listview);
    textView4 = (TextView) findViewById(R.id.textView4);
    adapter = new ArrayAdapter<String>(this, android.R.layout.simple_dropdown_item_1line, list);
    listview.setAdapter(adapter);
    dref = FirebaseDatabase.getInstance().getReference();
    uploads = new ArrayList<>();

    DatabaseReference dref = FirebaseDatabase.getInstance().getReference();
    dref= dref.child("Expenditure");

    dref.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot snapshot) {
            for (DataSnapshot postSnapshot : snapshot.getChildren()) {
                //Getting the data from snapshot
                DogExpenditure dogExpenditure = postSnapshot.getValue(DogExpenditure.class);
                uploads.add(dogExpenditure);
            }
            adapter = new MyAdapter(getApplicationContext(), uploads);
            recyclerView.setAdapter(adapter);
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }


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

私有列表上传；
MyAdapter适配器；
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity\u mystatement）；
listview=（listview）findViewById（R.id.listview）；
textView4=（TextView）findViewById（R.id.textView4）；
adapter=new ArrayAdapter（这是android.R.layout.simple\u下拉列表\u项\u 1行，列表）；
setAdapter（适配器）；
dref=FirebaseDatabase.getInstance（）.getReference（）；
uploads=新建ArrayList（）；
DatabaseReference dref=FirebaseDatabase.getInstance（）.getReference（）；
dref=dref.儿童（“支出”）；
dref.addValueEventListener（新的ValueEventListener（）{
@凌驾
公共无效onDataChange（数据快照快照）{
对于（DataSnapshot postSnapshot:snapshot.getChildren（））{
//从快照获取数据
DogExpression dogExpression=postSnapshot.getValue（dogExpression.class）；
上传。添加（DogExpense）；
}
adapter=新的MyAdapter（getApplicationContext（），上载）；
recyclerView.setAdapter（适配器）；
}
@凌驾
已取消的公共void（DatabaseError DatabaseError）{
}
取消后的公共无效（FirebaseError FirebaseError）{
System.out.println（“读取失败：+firebaseError.getMessage（））；
}
});

shift此行listview.setAdapter（adapter）；作为“创建自定义baseadapter”函数的最后一行，将firebase数据存储在arraylist中，并将其传递给adapter。@NiteshMishra示例..如果不介意的话

 public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {

private Context context;
private List<DogExpenditure> uploads;

public MyAdapter(Context context, List<DogExpenditure> uploads) {
    this.uploads = uploads;
    this.context = context;
}

@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.layout_firebase_images, parent, false);
    ViewHolder viewHolder = new ViewHolder(v);
    return viewHolder;
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
    DogExpenditure upload = uploads.get(position);

    holder.textViewName.setText(upload.getAmount());
    holder.textView1.setText(upload.getYourData());

}

@Override
public int getItemCount() {

    return uploads.size();
}

class ViewHolder extends RecyclerView.ViewHolder {

    public TextView textViewName;
    public ImageView imageView;

    public ViewHolder(View itemView) {
        super(itemView);

        textViewName = (TextView) itemView.findViewById(R.id.textViewName);
        textview1 = (TextView) itemView.findViewById(R.id.your_id);
    }
}
 }

private List<DogExpenditure> uploads;
MyAdapter adapter;
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_mystatement);
    listview = (ListView) findViewById(R.id.listview);
    textView4 = (TextView) findViewById(R.id.textView4);
    adapter = new ArrayAdapter<String>(this, android.R.layout.simple_dropdown_item_1line, list);
    listview.setAdapter(adapter);
    dref = FirebaseDatabase.getInstance().getReference();
    uploads = new ArrayList<>();

    DatabaseReference dref = FirebaseDatabase.getInstance().getReference();
    dref= dref.child("Expenditure");

    dref.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot snapshot) {
            for (DataSnapshot postSnapshot : snapshot.getChildren()) {
                //Getting the data from snapshot
                DogExpenditure dogExpenditure = postSnapshot.getValue(DogExpenditure.class);
                uploads.add(dogExpenditure);
            }
            adapter = new MyAdapter(getApplicationContext(), uploads);
            recyclerView.setAdapter(adapter);
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }


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