Question

我的ListView未显示数据，我使用适配器类将数据设置为ListView，但未显示。

MyAdapter类：

public class MyAdapter extends ArrayAdapter {
private Context context;
private LayoutInflater inflater;

private List<HashMap<String, String>> aList=new ArrayList<HashMap<String,String>>();
int[] to;
public MyAdapter(Context context, List<HashMap<String, String>> aList) {
    super(context, R.layout.mainlistviewchild, aList);

    this.context = context;
    this.aList = aList;
    inflater = LayoutInflater.from(context);
}



HashMap<String, String> m;
String[] aa;
String c;
List<String> myString = new ArrayList<String>();
@Override
public View getView(int position, View convertView, ViewGroup parent) {
    if (null == convertView) {
        convertView = inflater.inflate(R.layout.mainlistviewchild, parent);
    }

    TextView title1=(TextView)convertView.findViewById(R.id.maintitle);
    TextView description1=(TextView)convertView.findViewById(R.id.maindesc);
    TextView date=(TextView)convertView.findViewById(R.id.mainby);
    ImageView image1=(ImageView)convertView.findViewById(R.id.mainimage);
    TextView locstate=(TextView)convertView.findViewById(R.id.maindate);

    title1.setText(aList.get(position).get("Name"));
    description1.setText(aList.get(position).get("Email"));
    locstate.setText(aList.get(position).get("State"));
    date.setText(aList.get(position).get("Country"));
    Glide.with(context).load(aList.get(position).get("Image")).into(image1);

    return convertView;
}
}

MainActivity：

public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {

public MainActivity() {
    // Required empty public constructor
}
DatabaseReference ref;
DatabaseReference postRef;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    FirebaseDatabase.getInstance().setPersistenceEnabled(true);
    ref = FirebaseDatabase.getInstance().getReference();
    String stuff=getIntent().getExtras().getString("stuff");
    ListView listView=(ListView)findViewById(R.id.listView);
    final List<HashMap<String, String>> aList = new ArrayList<HashMap<String, String>>();
    final MyAdapter adapter = new MyAdapter(getApplicationContext(),aList);
    adapter.notifyDataSetChanged();
    listView.setAdapter(adapter);
    postRef=ref.child("Users");
    ref.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            aList.clear();
            for (DataSnapshot child : dataSnapshot.getChildren()) {

                for (DataSnapshot single : child.getChildren()) {
                    Map<String, Object> map = (Map<String, Object>) single.getValue();

                    String   name = (String) map.get("Name");
                    String   image = (String) map.get("Profileimage");
                    String   email = (String) map.get("Email");
                    String   address=(String) map.get("Address");
                    String   state=(String) map.get("State");
                  String  country=(String) map.get("Country");
                    String city=(String) map.get("City");
                    String knownplace=(String) map.get("Knownplace");
                    String postalcode=(String) map.get("Postalcode");


                    if (name!=null && image!=null && email!=null && address!=null && country!=null && state!=null && city!=null && knownplace!=null && postalcode!=null) {
                        String[] name1={name};
                        String[] email1={email};
                        String[] address1={address};
                        String[] image1={image};
                        String[] state1={state};
                        String[] country1={country};
                        String[] city1={city};
                        String[] knownplace1={knownplace};
                        String[] postalcode1={postalcode};
                        HashMap<String,String> data=new HashMap<String, String>();
                        for (int i=0; i<name1.length;i++) {
                            data.put("Name", name1[i]);
                            data.put("Email",email1[i]);
                            data.put("Address",address1[i]);
                            data.put("Image",image1[i]);
                            data.put("Country",country1[i]);
                            data.put("State",state1[i]);
                            data.put("City",city1[i]);
                            data.put("Knownolace",knownplace1[i]);
                            data.put("Postalcode",postalcode1[i]);
                        }
                        aList.add(data);
                        adapter.notifyDataSetChanged();
                        //progressBar.setVisibility(View.INVISIBLE);
                    }
                }
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }


    });

mainlistview.xml：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">


<ImageView
    android:layout_width="100dp"
    android:layout_height="100dp"
    android:id="@+id/mainimage"
    android:src="@drawable/profile"
    android:layout_below="@+id/relativeLayout"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true" />

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/relativeLayout">

</RelativeLayout>

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Description"
    android:textStyle="italic"
    android:textSize="20sp"
    android:id="@+id/maindesc"
    android:layout_below="@+id/maintitle"
    android:layout_toRightOf="@+id/mainimage"
    android:layout_toEndOf="@+id/mainimage" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Title"
    android:textStyle="bold"
    android:textSize="20sp"
    android:layout_below="@+id/relativeLayout"
    android:layout_toRightOf="@+id/mainimage"
    android:layout_toEndOf="@+id/mainimage"
    android:id="@+id/maintitle" />
<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Location"
    android:id="@+id/mainlocation"
    android:layout_below="@+id/maindesc"
    android:layout_toRightOf="@+id/mainimage"
    android:layout_toEndOf="@+id/mainimage" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceSmall"
    android:text="Date"
    android:id="@+id/maindate"
    android:layout_above="@+id/mainby"
    android:layout_toRightOf="@+id/mainimage"
    android:layout_toEndOf="@+id/mainimage" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceSmall"
    android:text="By"
    android:id="@+id/mainby"
    android:layout_alignBottom="@+id/mainimage"
    android:layout_toRightOf="@+id/mainimage"
    android:layout_toEndOf="@+id/mainimage" />
 </RelativeLayout>

ListView未显示任何数据有人可以说这个问题吗？

Answer 1

嘿@Shiv uday首先你需要把aList.add（数据）;在for循环中

Answer 2

您必须在适配器中覆盖getCount。

应该是

@Override
public int getCount() {
    return aList.size();
}

和convertView应该是：

convertView = inflater.inflate(R.layout.mainlistviewchild, parent, false);

Listview不显示从firebase获取的数据

2 个答案: