Question

我在ListView中获得了重复的项目。向后和向下滚动有时会更改项目顺序。我用谷歌搜索并发现许多线程报告了这个错误，但没有一个帮助我解决我的问题。

这是我的代码：

的活动：

package com.github.progval.SeenDroid;

import java.util.ArrayList;
import java.util.List;

import com.github.progval.SeenDroid.lib.Connection;
import com.github.progval.SeenDroid.lib.Message;
import com.github.progval.SeenDroid.lib.MessageFetcher;
import com.github.progval.SeenDroid.lib.Query.ParserException;

import android.app.Activity;
import android.app.ListActivity;
import android.content.SharedPreferences;
import android.os.Bundle;

public class ShowUserActivity extends ListActivity {
    private Connection connection;

    public ArrayList<Message> listMessages = new ArrayList<Message>();
    public MessageAdapter adapter;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.profile);
        this.connection = new Connection();
        this.setTitle(R.string.homefeed_title);


        this.listMessages = new MessageFetcher(this.connection).fetchUser();
        this.bindUi();
    }

    private void bindUi() {
        this.adapter = new MessageAdapter(this, this.listMessages);
        this.setListAdapter(adapter);

        // TODO Bind buttons
    }
}

MessageAdapter：

package com.github.progval.SeenDroid;

import java.util.ArrayList;
import java.util.List;
import java.util.zip.Inflater;

import com.github.progval.SeenDroid.lib.Message;

import android.content.Context;
import android.text.Layout;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.webkit.WebView;
import android.widget.ArrayAdapter;
import android.widget.BaseAdapter;
import android.widget.LinearLayout;
import android.widget.TextView;

public class MessageAdapter extends BaseAdapter {
    private Context context;
    private List<Message> items = new ArrayList<Message>();
    private int lastPosition = 0;

    public MessageAdapter(Context context, List<Message> items) {
        super();
        this.context = context;
        this.items = items;
    }

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

        if (null == convertView) {
            LinearLayout view;
            view = (LinearLayout) LinearLayout.inflate(this.context, R.layout.message, null);
            Log.d("SeenDroid", String.format("Get view %d", position));
            TextView title = new TextView(view.getContext());
            title.setText(this.items.get(position).getTitle());
            view.addView(title);
            return view;
        } else {
            return convertView;
        }
    }


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


    @Override
    public Object getItem(int location) {
        return this.items.get(location);
    }


    @Override
    public long getItemId(int arg0) {
        return arg0;
    }


}

顺便说一下，输出是：

D/SeenDroid(30939): Get view 0
D/SeenDroid(30939): Get view 1
D/SeenDroid(30939): Get view 2
D/SeenDroid(30939): Get view 3
D/SeenDroid(30939): Get view 4
D/SeenDroid(30939): Get view 5
D/SeenDroid(30939): Get view 6
D/SeenDroid(30939): Get view 7
D/SeenDroid(30939): Get view 8
D/SeenDroid(30939): Get view 0
D/SeenDroid(30939): Get view 16

此致 ProgVal

Answer 1

试试这个：

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

    if (null == convertView) {
        LinearLayout view = (LinearLayout) LinearLayout.inflate(this.context, 
            R.layout.message, null);
        Log.d("SeenDroid", String.format("Get view %d", position));
        TextView title = new TextView(view.getContext());
        title.setText(this.items.get(position).getTitle());
        view.addView(title);
        return view;
    } else {
        LinearLayout view = (LinearLayout) convertView;
        TextView title = (TextView) view.getChildAt(0);
        title.setText(this.items.get(position).getTitle());
        return convertView;
    }
}

解释：您获得了重复项，因为Android上的列表重用了UI对象。如果它不为null，则应该重用convertView而不是创建新的{{1}}。当然，您有责任为正在重用的实例设置适当的值。否则，该值将保留在最后一次“使用”中。

Answer 2

BOOL WINAPI WriteConsole(..., const VOID *lpBuffer, DWORD nNumberOfCharsToWrite, ..., ..);

Answer 3

ListView不保证您添加的项目的唯一性。这是你的责任。您正在使用ArrayList来存储项目，并且可以根据需要存储任意数量的重复项目。

如果要删除重复项，请将项目置于设置中，然后再次列入列表：

listMessages = new ArrayList<Messages>(new LinkedHashSet<Message>(listMessages))

LinkedHashSet将删除重复项，保留项目的初始顺序，ArrayList将允许按位置访问元素。

Answer 4

建议 - 在title.setText之后添加一条日志语句，并写入从getTitle（）获取的值。您可能会知道为什么会收到重复的条目。

Answer 5

您应该在ListAdapter中使用ViewHolder范例

可以在这里找到一个很好的例子： http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/view/List14.html

ListView中的重复条目

5 个答案: