ListView 在 Scroll 上显示错误的项目

Question

我有一个用于显示姓名的列表视图。如果我滚动屏幕，它会显示错误的名称。我知道这是一个根植于适配器的 getView 方法的常见错误，但是尽管遵循了许多现有讨论中提出的方法，但仍无法解决它。

我已经在下面粘贴了我的代码。如果有人可以识别错误，那就太好了。

自定义适配器

public class ListArrayAdapter extends ArrayAdapter<client> {

HashMap<String, Integer> hMap = new HashMap<String, Integer>();
private Context cntxt;
private List<client> client_list;
private int textviewres;

public ListArrayAdapter(Context context, int textViewResourceId, List<client> objects) {
    super(context,textViewResourceId,objects);
    this.cntxt = context;
    this.textviewres = textViewResourceId;
    this.client_list = objects;

    for(int j=0; j<client_list.size(); j++){

        Log.d("ListArrayAdapter", "Position No" +j +": " +client_list.get(j).getName());
        Log.d("ListArrayAdapter", "Total elements in the client list is  "+client_list.size());

    }
}


@Override
public long getItemId(int position) {
    client item = getItem(position);
    return item.getID();
}


@Override
public boolean hasStableIds() {
    return true;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {

    View clist;


    LayoutInflater inflater = (LayoutInflater) cntxt.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    if (convertView == null) {

        clist = inflater.inflate(textviewres, null);
        TextView tv = (TextView) clist.findViewById(R.id.textv);
        tv.setText(client_list.get(position).getName());

    } else {
        clist = convertView;
    }
    return clist;

}

}

Activity 运行 ListView

public class clients_list extends ActionBarActivity {


private database_handler obj;
private Context context;
static ArrayAdapter<String> adapter;
List<client> values;
ListView list;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_clients);

    list = (ListView) findViewById(R.id.clientlist);

    context = getBaseContext();
    obj = new database_handler(context);

    final List<String> listdata = new ArrayList<String>();

    values = obj.getAllClients();
    int listlength = values.size();

    for (int i = 0; i < listlength; ++i) {
        listdata.add(values.get(i).getName());
    }

    ListArrayAdapter adapter = new ListArrayAdapter(this,R.layout.custom_textv, values);

    list.setAdapter(adapter);

    //Define what happens after clicking the Add Client Button
    Button add_client_button = (Button) findViewById(R.id.addbutton);

    add_client_button.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            // Perform action on click
            Intent addclient = new Intent(v.getContext(), add_client.class);
            v.getContext().startActivity(addclient);
        }
    });

    list.setOnItemClickListener(new android.widget.AdapterView.OnItemClickListener() {

        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

            //Display Client Details
            Intent displayclient = new Intent(view.getContext(), display_clientdetails.class);

            Long db_id = parent.getAdapter().getItemId(position);

            String TAG = "client_list";
            Log.d(TAG,"Position is" +position +" ID is " +db_id);

            displayclient.putExtra("client_id",db_id);
            view.getContext().startActivity(displayclient);

        }

    });

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_clients, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {

    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

}

Activity

的布局

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
android:background="@color/green"
tools:context="com.example.jaya.myapplication.Clients">

<Button
    android:id="@+id/addbutton"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:drawableLeft="@drawable/ic_addnewclient"
    android:text="@string/add_client"
    android:textColor="@color/white"/>

<ListView
    android:id="@+id/clientlist"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_below="@id/addbutton"
    android:dividerHeight="5dp">

</ListView>

Answer 1

我觉得你这里有问题

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

View clist;


LayoutInflater inflater = (LayoutInflater) cntxt.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null) {

    clist = inflater.inflate(textviewres, null);
    TextView tv = (TextView) clist.findViewById(R.id.textv);
    tv.setText(client_list.get(position).getName());

} else {
    clist = convertView;
}
return clist;

}

因此，当您的转换视图不为空时，您不会像这样填充列表

     TextView tv = (TextView) clist.findViewById(R.id.textv);
    tv.setText(client_list.get(position).getName());

我一般都是这样做的

     public class MyHolder {
    TextView keyword, tweetCount;
    public MyHolder(View v) {
        keyword = (TextView) v.findViewById(R.id.keyword_text);
        tweetCount = (TextView) v.findViewById(R.id.tweets_count_text);
    }

}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    View view = convertView;
    MyHolder holder;
    if (view == null) {
        view = LayoutInflater.from(mContext).inflate(R.layout.keyword_contents, parent, false);
        holder = new MyHolder(view);
        view.setTag(holder);
    } else {
        holder = (MyHolder) view.getTag();
    }
    holder.keyword.setText(list.get(position).getKeyword());
    holder.tweetCount.setText(String.valueOf(list.get(position).getCount()));
    return view;
}

我认为 holder 会做的不是一次又一次地查找 textview 它只会 findviewbyid 一次

Answer 2

我可以在阅读 ListView in ArrayAdapter order get's mixed up when scrolling 后自行解决问题。

错误出在getView方法上。我已经将用于将名称分配给 ListView 中的 TextView 的代码放置在 If Block for (convertView == null) 中。由于在显示第一组项目后 convertView 不为 null，因此代码无法为 Textviews 分配新名称 wand 只是使用 Android 放置在 convertView 中的可重用项目。

正确的getView代码如下：

    @Override
public View getView(int position, View convertView, ViewGroup parent) {

    View clist = convertView;

    if (convertView == null) {
        LayoutInflater inflater = (LayoutInflater) cntxt.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        clist = inflater.inflate(textviewres, null);
    }
    TextView tv = (TextView) clist.findViewById(R.id.textv);
    tv.setText(client_list.get(position).getName());

    return clist;

}

Answer 3

鼓励使用 ViewHolder 模式在 getView(...) 中制作 View。否则只需更改您的代码即可：

@Override
public View getView(int position, View convertView, ViewGroup parent) {

   View clist;

   LayoutInflater inflater = (LayoutInflater) cntxt.getSystemService (Context.LAYOUT_INFLATER_SERVICE);

    clist = inflater.inflate(textviewres, null);
    TextView tv = (TextView) clist.findViewById(R.id.textv);
    tv.setText(client_list.get(position).getName());

    return clist;
}

希望对您有所帮助！

ListView 在 Scroll 上显示错误的项目

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