没有从自定义适配器调用getView

Question

所以我一直潜伏着试图找到答案。我正在探洞。我需要一双新鲜的眼睛。我的CustomAdapter中的My View getView未被调用。

public class User_List_Fragment extends ListFragment {
    View view;
    DBHelper db;
    List<UTable> userList;
    ListView list;
    TextView id, firstName, lastName, job;
    String mId;

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.view_users_fragment, container, false);

        list = (ListView) view.findViewById(android.R.id.list);
        db = new DBHelper(getActivity());
        userList = db.getUserList();

        class CustomAdapter extends ArrayAdapter<String> {
             private Context context;

            public CustomAdapter(Context context, int textViewResourceId, List<UTable> userList) {
                    super(context, textViewResourceId);
                    this.context = context;
             }

            @Override
            public View getView(int position, View convertView, ViewGroup parent) {
                View row = convertView;
                if (row == null) {
                    LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                    row = inflater.inflate(R.layout.custom_list_row, null);
                }

                id = (TextView) row.findViewById(R.id.list_id);
                firstName = (TextView) row.findViewById(R.id.list_first_name);
                lastName = (TextView) row.findViewById(R.id.list_last_name);
                job = (TextView) row.findViewById(R.id.list_job);               
                for (UTable uTable : userList) {
                    id.setText(String.valueOf(uTable.getId()));
                    firstName.setText(uTable.getFirstName());
                    lastName.setText(uTable.getLastName());
                    job.setText(uTable.getJob());

                    String mId = String.valueOf(uTable.getId());
                    String mF = uTable.getFirstName();
                    String mL = uTable.getLastName();
                    String j = uTable.getJob();

                    Log.v("ID", mId);
                    Log.v("First Name", mF);
                    Log.v("Last Name", mL);
                    Log.v("Job", j);                    
                 }              
                return row;
            }           
        }
        list.setAdapter(new CustomAdapter(getActivity().getApplicationContext(), R.layout.custom_list_row, userList));
        db.close();
        return view; 
    }
}

view_users_fragment.xml

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

        <ListView 
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@android:id/list"
            android:gravity="center" />

        <TextView 
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/no_data"
            android:id="@android:id/empty"
            android:gravity="center"/>

    </LinearLayout>

custom_list_row.xml

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

    <TextView
        android:id="@+id/list_id" 
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight=".10"
        android:text="@string/one"/>

    <TextView
        android:id="@+id/list_first_name" 
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight=".25"
        android:text="@string/first_name_hint"/>

    <TextView
        android:id="@+id/list_last_name" 
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight=".25"
        android:text="@string/last_name_hint"/>

    <TextView
        android:id="@+id/list_job"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight=".5"
        android:text="@string/job_hint" />

</LinearLayout>

而是调用默认的TextView。当列表为空并且声明“未找到数据”时会发生这种情况。我已经测试了数据库的查询，它的工作原理。如果我将我的for循环放在getView之外，它会返回结果。我想我正在弄乱我的CustomAdapter的构造函数，但我似乎无法搞清楚。任何帮助表示赞赏。

编辑重新确定的代码

User_List_Fragment.java

public class User_List_Fragment extends ListFragment {
    View view;
    DBHelper db;
    List<UTable> userList;
    ListView list;
    CustomAdapter adapter;

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.view_users_fragment, container, false);

        db = new DBHelper(getActivity());
        userList = db.getUserList();

        list = (ListView) view.findViewById(android.R.id.list);
        adapter = new CustomAdapter(getActivity().getApplicationContext(), R.layout.custom_list_row, userList);     
        list.setAdapter(adapter);

        db.close();
        return view; 
    }
}

CustomAdapter.java

public class CustomAdapter extends ArrayAdapter<UTable> {
     private Context context;

    public CustomAdapter(Context context, int textViewResourceId, List<UTable> userList) {
        super(context, textViewResourceId);
        this.context = context;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        if (convertView== null) {
            convertView = View.inflate(context, R.layout.custom_list_row, null);
        }

        TextView id = (TextView) convertView.findViewById(R.id.list_id);
        TextView firstName = (TextView) convertView.findViewById(R.id.list_first_name);
        TextView lastName = (TextView) convertView.findViewById(R.id.list_last_name);
        TextView job = (TextView) convertView.findViewById(R.id.list_job);

        UTable uTable = getItem(position);
        if (uTable != null) {
            id.setText(String.valueOf(uTable.getId()));
            firstName.setText(uTable.getFirstName());
            lastName.setText(uTable.getLastName());
            job.setText(uTable.getJob());

            Log.v("JOB", uTable.getJob());
        }
        return convertView;
    }           
}

Answer 1

好的，我刚看了一眼，你误解了如何使用适配器。

传入的每一行数据都会调用getView。在内部获取视图时，您应该getItem(position)并使用该对象数据填写字段

更清楚 - 你根本不需要for循环，只要你在heirarchy中的某个地方扩展baseadapter就会自动循环

示例

  class CustomAdapter extends ArrayAdapter<UTable> {

        public CustomAdapter(Context context, int textViewResourceId, List<UTable> userList) {
                super(context, textViewResourceId, userlist);
         }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            if (convertView== null) {
               convertView = View.inflate(R.layout.custom_list_row, null);
            }

            //google the view holder pattern when you are more exerienced
            TextView id = (TextView) row.findViewById(R.id.list_id);
            TextView firstName = (TextView) row.findViewById(R.id.list_first_name);
            TextView lastName = (TextView) row.findViewById(R.id.list_last_name);
            TextView job = (TextView) row.findViewById(R.id.list_job);               

            UTable item = getItem(position);
            job.setText(item.getJob());
            ...

            return convertView;
        }           
    }

破碎的事情：

  //Java classes should be named like UserListFragment 
  public class User_List_Fragment extends ListFragment {

     //You shouldnt have these views here, they arent part of the fragmetn
     //they are part of each row in the list and so will keep changing!
     TextView id, firstName, lastName, job;
     String mId;

     public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

       ...

           //You are inside the onCreateView method here - yo ucant decalre a class inside a method!
           class CustomAdapter extends ArrayAdapter<UTable> {

Answer 2

您需要将自定义适配器设置为listview。 list.setAdapter(customAdapter)

Answer 3

您也需要将数据传递给构造函数，使用以下代码更改Constructor方法：

public CustomAdapter(Context context, int textViewResourceId, List<UTable> userList) {
        super(context, textViewResourceId , userList);
        this.context = context;
             }

或使用BaseAdapter类而不是ArrayAdapter并覆盖GetCount（）和GetItem（）方法，并在GetCount方法中返回列表的大小

Answer 4

你的getview方法背后的原因是......

为了让适配器知道它有多少行，您必须从Constructor传递数据或重写getCount方法。

你没有做任何事情。所以适配器不知道任何数据。

所以

使用以下任何构造函数

    http://developer.android.com/reference/android/widget/ArrayAdapter.html#ArrayAdapter%28android.content.Context,%20int,%20T[]%29

http://developer.android.com/reference/android/widget/ArrayAdapter.html#ArrayAdapter%28android.content.Context,%20int,%20int,%20T[]%29

http://developer.android.com/reference/android/widget/ArrayAdapter.html#ArrayAdapter%28android.content.Context,%20int,%20int,%20T[]%29

http://developer.android.com/reference/android/widget/ArrayAdapter.html#ArrayAdapter%28android.content.Context,%20int,%20int,%20java.util.List%3CT%3E%29

或 覆盖getCount方法

http://developer.android.com/reference/android/widget/ArrayAdapter.html#getCount%28%29

你完成了。 希望有帮助