android - 为什么 ListView 每 6 个项目重复一次？

Question

我有一个 ListView，它由具有特定布局的自定义适配器填充。适配器映射到具有特定元素的 HashMap，其中包含每个 ListView 元素的数据。

hashMap 中的数据是正确的，但是 ListView 重复绘制每 6 个相同的第 6 个元素，直到它到达 Map 的末尾？？

My Display 允许显示 5 个项目，如果你滚动一点它是 6 个项目。

这里是Adapter的代码，ListActivity的相关代码和ListView的布局文件。

请帮忙，我不知道为什么会这样。

package de.View;

import java.util.ArrayList;
import java.util.Map;

import de.carSync.R;
import de.Common.Date_Conversion;
import de.Common.GUI_Output;
import de.Model.DriversLog.Fahrt;
import de.Model.DriversLog.Geladene_Fahrten;

import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

public class Fahrten_List_Adapter extends BaseAdapter{

    private static  String TAG = "Fahrten_List_Adapter";

    private Map<Integer,Fahrt> fahrten_Liste;

    private final LayoutInflater mLayoutInflater;

    int zeilen_Layout;

    public Fahrten_List_Adapter(Context ctx, Map<Integer,Fahrt> f_l, int zeilen_Layout){
        this.zeilen_Layout = zeilen_Layout;
        fahrten_Liste = f_l;
        mLayoutInflater = (LayoutInflater) ctx.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

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

    @Override
    public Object getItem(int pos) {
        return fahrten_Liste.get(pos);
    }

    @Override
    public long getItemId(int pos) {
        return 0;
    }

    public void clear(){
        fahrten_Liste.clear();
    }

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

        if(convertView == null){
            convertView = mLayoutInflater.inflate(zeilen_Layout, null);

            Log.v(TAG,"getView   :" + pos);

            ((TextView) convertView.findViewById(R.id.FahrtID)).setText( (String) ((Fahrt) getItem(pos)).get_Fahrt_ID() );

            ((TextView) convertView.findViewById(R.id.Kennzeichen)).setText( (String) ((Fahrt) getItem(pos)).get_Kennzeichen() );

            ((TextView) convertView.findViewById(R.id.Abfahrts_Strasse)).setText( (String) ((Fahrt) getItem(pos)).get_Abfahrts_Strasse().toString() );

            ((TextView) convertView.findViewById(R.id.Ankunfts_Strasse)).setText( (String) ((Fahrt) getItem(pos)).get_Ankunfts_Strasse().toString() );

            ((TextView) convertView.findViewById(R.id.Fahrttyp)).setText( (String) GUI_Output.get_Fahrttyp((Object) ((Fahrt) getItem(pos)).get_Fahrttyp() ));

            ((TextView) convertView.findViewById(R.id.Abfahrts_Stadt)).setText( (String) ((Fahrt) getItem(pos)).get_Abfahrts_Stadt().toString() );

            ((TextView) convertView.findViewById(R.id.Ankunfts_Stadt)).setText( (String) ((Fahrt) getItem(pos)).get_Ankunfts_Stadt().toString() );

            ((TextView) convertView.findViewById(R.id.Dauer)).setText( (String) ((Fahrt) getItem(pos)).get_Fahrt_Dauer().toString() );

            ((TextView) convertView.findViewById(R.id.Abfahrts_Zeit2)).setText( (String) Date_Conversion.get_GUI_Date(  ((Fahrt) getItem(pos)).get_Abfahrtszeit_Date() ));

            ((TextView) convertView.findViewById(R.id.Ankunfts_Zeit2)).setText( (String) Date_Conversion.get_GUI_Date(  ((Fahrt) getItem(pos)).get_Ankunftszeit_Date() ));

            ((TextView) convertView.findViewById(R.id.Entfernung)).setText( (String) ((Fahrt) getItem(pos)).get_Fahrt_Entferung().toString() );

            ((TextView) convertView.findViewById(R.id.Abfahrts_Km)).setText( (String) ((Fahrt) getItem(pos)).get_Abfahrt_km().toString() );

            ((TextView) convertView.findViewById(R.id.Ankunfts_Km)).setText( (String) ((Fahrt) getItem(pos)).get_Ankunfts_km().toString() );

        //}


    }
        return convertView;


    }

}

---

package de.View;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URISyntaxException;
import java.util.Stack;

import org.json.JSONException;

import de.carSync.R;
import de.Controler.Drivers_Log_Controller;
import de.Controler.Global_Controller;
import android.app.Activity;
import android.app.ListActivity;
import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnClickListener;
import android.widget.AbsListView;
import android.widget.Button;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.Toast;

public class Drivers_Log_View extends ListActivity implements AbsListView.OnScrollListener {

    Drivers_Log_Controller d_l_c;

    Fahrten_List_Adapter f_l_a_ohne_Auswahl;


    ListView view_ohne_auswahl;


    static String TAG = "Drivers_Log_View";

    /** Called when the activity is first created. */
    @SuppressWarnings("unchecked")
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.d_l_c = (Drivers_Log_Controller) Global_Controller.get_Controller_Map().get("actual d_l_c");

        this.setContentView(R.layout.list_view);


        try {
            d_l_c.lade_Standard_Fahrten(null);              
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (URISyntaxException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        Log.v(TAG, "now creating Fahrten_List_Adapter");
        f_l_a_ohne_Auswahl = new Fahrten_List_Adapter(this, d_l_c.get_Fahrten(), R.layout.fahrt_linear_ohne_auswahl);
        this.setListAdapter(f_l_a_ohne_Auswahl);
        d_l_c.listAdapter = this.getListAdapter();

        ListView lv = this.getListView();

        lv.setOnScrollListener(this);

        //addListeners();

    }

    public void init() {
        //
    }

    public Drivers_Log_Controller get_D_L_C() {
        return this.d_l_c;
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.fahrtenbuch_menue_bar, menu);
        Log.v(TAG, "Do I get here");
        return true;
    }

    @Override
    public void onListItemClick(ListView l, View v, int position, long id) {
        Log.v(TAG, "ListView Position    :" + position);
        super.onListItemClick(l, v, position, id);
        Global_Controller.start_Fahrt(position);
    }

    @SuppressWarnings("unchecked")
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {

        case R.id.fahrtenbuch: {

            try {
                d_l_c.lade_Standard_Fahrten(null);
            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (URISyntaxException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            this.setListAdapter(d_l_c.get_List_Adapter());

        }
            break;

        case R.id.unv_Fahrten: {

            try {
                d_l_c.lade_Unvollstaendige_Fahrten(null);
            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            this.setListAdapter(d_l_c.get_List_Adapter());

        }
            break;

        case R.id.filter: {
            Global_Controller.start_Filter();
            break;
        }

        case R.id.zusammenfassen: {
            Log.v(TAG, "Menu --- Zusammenfassen");
            Global_Controller.start_Zusammenfassen();
        }
            break;

        }
        return true;
    }

    @Override
    public void onScroll(AbsListView arg0, int firstVisible, int visibleCount,
            int totalCount) {
        Log.v(TAG, "firstVisible   :" + firstVisible);
        Log.v(TAG, "visibleCount   :" + visibleCount);
        Log.v(TAG, "totalCount   :" + totalCount);

        boolean endReached = firstVisible + visibleCount >= totalCount;

        if (endReached) {
            try {
                Log.v(TAG, "EndReached");

                d_l_c.nachladen_Fahrten(totalCount);

            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

    }

    @Override
    public void onScrollStateChanged(AbsListView arg0, int arg1) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onResume() {
        super.onResume();
        this.setListAdapter(d_l_c.get_List_Adapter());
        Log.v(TAG, "OnResume");
    }



}

---

<?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:id="@android:id/list" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#FFFFFF" android:divider="#000000" android:dividerHeight="3px" android:cacheColorHint="#FFFFFF" /> 
  <TextView android:id="@android:id/empty" android:text="nix da...." android:layout_width="match_parent" android:layout_height="match_parent" android:background="#FFFFFF" android:divider="#000000" android:dividerHeight="3px" android:cacheColorHint="#FFFFFF" /> 
  </LinearLayout>

Answer 1

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

    if(convertView == null){
        convertView = mLayoutInflater.inflate(zeilen_Layout, null);

        //Assignment code
    }
    return convertView;
}

发生这种情况的原因是您如何定义此方法(即 getView())。如果 convertView 对象为 null，它只会修改它，但在项目的第一页被填充后，Android 将开始回收 View 对象。这意味着传入的第七个 不是 null - 它是之前滚动到屏幕顶部的对象(第一个项目)。

条件导致您只返回传递给方法的内容，因此它似乎一遍又一遍地重复相同的 6 个项目。