如何从Firebase获取字符串列表来填充微调器 [英] How to get a String List from Firebase to fill a Spinner

问题描述

我的数据库是这样安排的：

我想从 areaName 获取所有的值作为一个字符串列表或任何形式的列表，并用它来填充一个微调。我得到的问题是，它只检索最后的值（在这种情况下纽约）。这是我的实际代码：

pre $ $ $ $ $ $ $ $ $ $ $ $ $ fDatabaseRoot.child（areas）。addValueEventListener（new ValueEventListener（）{
@Override
public void onDataChange（DataSnapshot dataSnapshot）{
for（DataSnapshot areaSnapshot：dataSnapshot.getChildren（））{
String areaName = areaSnapshot.child（areaName）。getValue（String。 class）;

Spinner areaSpinner =（Spinner）findViewById（R.id.spinner）;
final String [] areas = {areaName};
ArrayAdapter< String> areasAdapter = new ArrayAdapter< String>（UAdminActivity.this，android.R.layout.simple_spinner_item，areas）;
areasAdapter.setDropDownViewResource（android.R.layout.simple_spinner_dropdown_item）;
areaSpinner.setAdapter（areasAdapter）;
}
}

@覆盖
public void onCancelled（DatabaseError databaseError）{

}
}）;

解决方案

那么你需要做什么：

  fDatabaseRoot.child（areas）。addValueEventListener（new ValueEventListener（）{ 
 @Override 
 public void onDataChange（DataSnapshot dataSnapshot）{
 //最好使用List，因为您不知道返回的迭代器的大小
 // dataSnapshot.getChildren（）到
 //初始化数组
 final List< String> areas = new ArrayList< String>（）; 
 
 for（DataSnapshot areaSnapshot：dataSnapshot.getChildren （））{
 String areaName = areaSnapshot.child（areaName）。getValue（String.class）; 
 areas.add（areaName）; 
} 
 
 Spinner areaSpinner =（Spinner）findViewById（R.id.spinner）; 
 ArrayAdapter< String> areasAdapter = new ArrayAdapter< String>（UAdminActivity.this ，android.R.layout.simple_spinner_item，areas）; 
 areasAdapter.setDropDownViewResource（android.R.layout.simple_spinner_dropdown_item）; 
 areaSpinner.setAdapter（areasAdapter）; 
} 
 
 @Override 
 public void onCancelled（DatabaseError databaseError）{
 
 $ b}）; 
  

我希望这有助于您！

。

my database is arranged like this:

I want to get all the values from areaName as a String List or any form of list and use it to populate a Spinner. The problem I am getting is that it only retrieves the last value (in this case "New York"). This is my actual code:

fDatabaseRoot.child("areas").addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            for (DataSnapshot areaSnapshot: dataSnapshot.getChildren()) {
                String areaName = areaSnapshot.child("areaName").getValue(String.class);

                Spinner areaSpinner = (Spinner) findViewById(R.id.spinner);
                final String[] areas = {areaName};
                ArrayAdapter<String> areasAdapter = new ArrayAdapter<String>(UAdminActivity.this, android.R.layout.simple_spinner_item, areas);
                areasAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
                areaSpinner.setAdapter(areasAdapter);
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

解决方案

I don't test that code but, more or less, that is what you have to do:

fDatabaseRoot.child("areas").addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        // Is better to use a List, because you don't know the size 
        // of the iterator returned by dataSnapshot.getChildren() to
        // initialize the array
        final List<String> areas = new ArrayList<String>();

        for (DataSnapshot areaSnapshot: dataSnapshot.getChildren()) {
            String areaName = areaSnapshot.child("areaName").getValue(String.class);
            areas.add(areaName);
        }

        Spinner areaSpinner = (Spinner) findViewById(R.id.spinner);
        ArrayAdapter<String> areasAdapter = new ArrayAdapter<String>(UAdminActivity.this, android.R.layout.simple_spinner_item, areas);
        areasAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        areaSpinner.setAdapter(areasAdapter);
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {

    }
});

I hope it's helps!

Regards.

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