为什么 ListView 每 6 项重复一次? [英] Why did the ListView repeated every 6th item?
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问题描述
我有一个 ListView，它由具有特定布局的自定义适配器填充.Adapter 被映射到一个 HashMap，其中包含每个 ListView 元素的数据的特定元素.
I have a ListView that is filled by a Custom Adapter with a specific Layout. The Adapter is mapped to a HashMap with the specific Elements that contains the Data for each ListView Element.
hashMap 中的Data 是正确的，但是ListView 重复每隔6'th 再次绘制相同的6'th Elements，直到到达Map 的末尾??
The Data in the hashMap is correct, but the ListView repeats to draw every 6'th the same 6'th Elements again, till it reaches the end of the Map??
My Display 允许显示 5 个项目，如果你滚动一点它是 6 个项目.
My Display allows to display 5 items, if you sroll a litte it's 6 items.
这里是Adapter的Code，ListActivity的相关Code和ListView的布局文件.
Here is the Code of the Adapter, the relevant Code of the ListActivity and the layout file of the ListView.
请帮忙，我不知道为什么会这样.
Please help, I've no Idea why this happens.
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;
}
}
<小时>
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");
}
}
<小时>
<?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>
推荐答案
@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()).如果它是null，它只会修改convertView 对象，但是当第一页items 被填满后，Android 将开始回收 View 对象.这意味着，即传入 的第七个不为空 - 它是先前从屏幕顶部滚动的对象(第一项).
The reason this is happening is because of how you've defined this method (which is getView()). It only modifies the convertView object if it is null, but after the first page of items is filled Android will start recycling the View objects. This means that i.e. the seventh one that gets passed in is not null - it is the object that scrolled off the top of the screen previously (the first item).
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 项.
The conditional causes you just return what was passed in to the method so it appears to repeat the same 6 items over and over.
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