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虽然解析XML到列表视图不能显示任何东西在列表视图

分类: 技术问答 • 2022-07-20 17:19:57
问题描述：

我已经解析了一个XML并在列表视图中使用它们。但有一个问题。我会在这里写两节课。其中之一是HaberAdapter.java表示我的自定义适配器类。虽然解析XML到列表视图不能显示任何东西在列表视图

package haberler; 

import java.util.Currency; 

import com.applogist.kusadasibelediyesi.R; 
import com.nostra13.universalimageloader.core.ImageLoader; 
import com.nostra13.universalimageloader.core.ImageLoaderConfiguration; 

import android.content.Context; 
import android.text.Html; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.webkit.WebView.FindListener; 
import android.widget.AdapterView; 
import android.widget.AdapterView.OnItemClickListener; 
import android.widget.BaseAdapter; 
import android.widget.ImageView; 
import android.widget.TextView; 
import android.widget.Toast; 

public class HaberAdapter extends BaseAdapter implements OnItemClickListener { 

HaberRSS haberrss = null; 
private ImageLoader imageloader; 
Context context; 
private LayoutInflater inflater = null; 

public HaberAdapter(Context context,HaberRSS haberrss) { 
    this.context = context; 
    this.haberrss = haberrss; 
    inflater = (LayoutInflater)    context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
    imageloader = ImageLoader.getInstance(); 
    imageloader.init(ImageLoaderConfiguration.createDefault(context)); 
} 


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

@Override 
public HaberlerItems getItem(int position) { 
    return haberrss.getItems().get(position); 
} 

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

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

     HaberlerItems currentItem = (HaberlerItems)getItem(position); 

     TextView lblTitle = (TextView) vi.findViewById(R.id.lblTitle); 
     TextView lblDescription = (TextView) vi.findViewById(R.id.lblDescription); 
     ImageView imgHaber = (ImageView) vi.findViewById(R.id.imgHaber); 

     lblTitle.setText(currentItem.getTitle()); 
     lblDescription.setText(currentItem.getDescription()); 
     imageloader.displayImage(currentItem.getImageUrl(), imgHaber); 


    return vi; 
} 

@Override 
public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
    Toast.makeText(context, String.valueOf(position), Toast.LENGTH_SHORT).show(); 

}

}

项目是我从

public class HaberlerItems { 

private String title; 
    private String description; 
    private String shortDesc; 
    private String dateAdded; 
    private List<HaberlerImage> imageList; 
    private String imageUrl; 

public String getImageUrl() { 
    return imageUrl; 
} 

public void setImageUrl(String imageUrl) { 
    this.imageUrl = imageUrl; 
} 

public List<HaberlerImage> getImageList() { 
    return imageList; 
} 

public void setImageList(List<HaberlerImage> imageList) { 
    this.imageList = imageList; 
} 

public HaberlerItems() { 
    setTitle(null); 
    setDescription(null); 
    setShortDesc(null); 
    setDateAdded(null); 
} 

public void setTitle(String title) { 
    this.title = title; 
} 

public String getTitle() { 
    return title; 
} 

public void setDescription(String description) { 
    this.description= description; 
} 

public String getDescription() { 
    return description; 
} 

public String getShortDesc() { 
    return shortDesc; 
} 

public void setShortDesc(String shortDesc) { 
    this.shortDesc = shortDesc; 
} 

public String getDateAdded() { 
    return dateAdded; 
} 

public void setDateAdded(String dateAdded) { 
    this.dateAdded = dateAdded; 
}

}

得到当我执行的应用程序没有什么是对列表视图显示。换句话说，显示是一个空的列表视图。我无法找到问题。

也是haber_rss_item.xml是;

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" > 

    <LinearLayout 
    android:id="@+id/lnMain" 
    android:layout_width="match_parent" 
    android:layout_height="100dip" 
    android:layout_marginBottom="5dip" 
    android:layout_marginLeft="5dip" 
    android:layout_marginRight="5dip" 
    android:layout_marginTop="5dip" 
    android:orientation="vertical" > 

    <LinearLayout 
     android:id="@+id/lnUst" 
     android:layout_width="match_parent" 
     android:layout_height="20dip" 
     android:layout_marginLeft="5dip" 
     android:layout_marginRight="5dip" 
     android:gravity="left|center" > 

     <TextView 
      android:id="@+id/lblTitle" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:lines="1" 
      android:maxLines="1" 
      android:text="" 
      android:textColor="@color/blue" 
      android:textSize="14sp" > 
     </TextView> 
    </LinearLayout> 

    <LinearLayout 
     android:id="@+id/lnAlt" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_marginBottom="5dip" 
     android:layout_marginLeft="5dip" 
     android:layout_marginRight="5dip" 
     android:gravity="center" 
     android:weightSum="10" > 

     <LinearLayout 
      android:id="@+id/lnImage" 
      android:layout_width="0dip" 
      android:layout_height="match_parent" 
      android:layout_weight="3" > 

      <ImageView 
       android:id="@+id/imgHaber" 
       android:layout_width="match_parent" 
       android:layout_height="match_parent" 
       android:scaleType="fitXY" > 
      </ImageView> 
     </LinearLayout> 

     <LinearLayout 
      android:id="@+id/lnDescription" 
      android:layout_width="0dip" 
      android:layout_height="match_parent" 
      android:layout_weight="6" > 

      <TextView 
       android:id="@+id/lblDescription" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:layout_marginLeft="2dip" 
       android:layout_marginRight="2dip" 
       android:maxLines="5" 
       android:text="" 
       android:textColor="@color/black" 
       android:textSize="12sp" > 
      </TextView> 
     </LinearLayout> 

     <LinearLayout 
      android:id="@+id/lnOk" 
      android:layout_width="0dip" 
      android:layout_height="wrap_content" 
      android:layout_weight="1" 
      android:gravity="center" > 

      <ImageView 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" > 
      </ImageView> 
     </LinearLayout> 
    </LinearLayout> 
</LinearLayout>

答

贵R.layout.haber_rss_item包含R.id.lblTitle。有时，当引用来自不同布局的View时，它不会显示错误。但是，在RunTime抛出NullPointerException。

建议：张贴StackTrace会有帮助。

+0

是布局包含R.id.lblTitle。我将在此处将xml写入此处 – emreturka

+0

LogCat中是否有任何错误或其他信息？发布您的LogCat输出.. – Krrishnaaaa

+0

没有在LogView中的任何错误。 – emreturka

答 

try something like this .. 

    import java.io.IOException; 
    import java.io.InputStream; 
    import java.util.ArrayList; 
    import java.util.HashMap; 

    import org.w3c.dom.Document; 
    import org.w3c.dom.Element; 
    import org.w3c.dom.NodeList; 

    import android.app.ListActivity; 
    import android.content.Intent; 
    import android.graphics.drawable.GradientDrawable; 
    import android.os.Bundle; 
    import android.view.View; 
    import android.widget.AdapterView; 
    import android.widget.AdapterView.OnItemClickListener; 
    import android.widget.ListAdapter; 
    import android.widget.ListView; 
    import android.widget.SimpleAdapter; 
    import android.widget.TextView; 

    import com.google.ads.AdRequest; 
    import com.google.ads.AdView; 

    public class AndroidXMLParsingActivity extends ListActivity { 

     static final String KEY_ITEM = "item"; // parent node 
     static final String KEY_ID = "id"; 
     static final String KEY_NAME = "name"; 
     static final String KEY_ADDRESS = "address"; 
     static final String KEY_PHONE = "phone"; 
     static final String KEY_ATTRACTION = "attraction"; 
     String xml; 
     int mIndex; 

     @Override 
     public void onCreate(Bundle savedInstanceState) { 
      super.onCreate(savedInstanceState); 
      setContentView(R.layout.display); 
      Intent in = getIntent(); 
      mIndex = Integer.parseInt(in.getStringExtra("value")); 

      ArrayList<HashMap<String, String>> menuItems = new ArrayList<HashMap<String, String>>(); 
      XMLParser parser = new XMLParser(); 
      switch (mIndex) { 
      case 0: 
       InputStream stream = getResources() 
         .openRawResource(R.raw.myxml); 
       try { 
        byte[] buffer = new byte[stream.available()]; 
        stream.read(buffer); 
        stream.close(); 
        xml = new String(buffer); 
       } catch (IOException e) { 
        // Error handling 
       } 
       break; 

      } 

      Document doc = parser.getDomElement(xml); // getting DOM element 
      NodeList nl = doc.getElementsByTagName(KEY_ITEM); 
      for (int i = 0; i < nl.getLength(); i++) { 
       HashMap<String, String> map = new HashMap<String, String>(); 
       Element e = (Element) nl.item(i); 
       map.put(KEY_ID, parser.getValue(e, KEY_ID)); 
       map.put(KEY_NAME, parser.getValue(e, KEY_NAME)); 
       map.put(KEY_ADDRESS, parser.getValue(e, KEY_ADDRESS)); 
       map.put(KEY_PHONE, parser.getValue(e, KEY_PHONE)); 
       map.put(KEY_ATTRACTION, parser.getValue(e, KEY_ATTRACTION)); 
       menuItems.add(map); 
      } 

      ListAdapter adapter = new SimpleAdapter(this, menuItems, 
        R.layout.list_item, new String[] { KEY_NAME, KEY_ADDRESS, 
          KEY_PHONE, KEY_ATTRACTION }, new int[] { R.id.name, 
          R.id.desciption, R.id.cost, R.id.sttraction }); 

      setListAdapter(adapter); 
      ListView lv = getListView(); 

      lv.setOnItemClickListener(new OnItemClickListener() { 

       @Override 
       public void onItemClick(AdapterView<?> parent, View view, 
         int position, long id) { 
        String val = "" + mIndex; 
        Intent i = new Intent(getApplicationContext(), 
          MallFinderActivity.class); 
        i.putExtra("value", val); 
        i.putExtra("position", "" + position); 
        String mallName = ((TextView) view.findViewById(R.id.name)) 
          .getText().toString(); 
        i.putExtra("mall", mallName); 
        startActivity(i); 
       } 
      }); 
     } 
    } 

this is my listitem xml : 



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

     <LinearLayout 
      xmlns:android="http://schemas.android.com/apk/res/android" 
      android:layout_width="fill_parent" 
      android:layout_height="wrap_content" 
      android:orientation="vertical" > 

      <!-- Name Label --> 

      <TextView 
       android:id="@+id/name" 
       android:layout_width="fill_parent" 
       android:layout_height="wrap_content" 
       android:paddingBottom="2dip" 
       android:paddingTop="6dip" 
       android:textColor="#dc6800" 
       android:textSize="16sp" 
       android:textStyle="bold" /> 
      <!-- Description label --> 

      <LinearLayout 
       xmlns:android="http://schemas.android.com/apk/res/android" 
       android:layout_width="fill_parent" 
       android:layout_height="wrap_content" 
       android:orientation="horizontal" > 

       <TextView 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:gravity="left" 
        android:text="Address: " 
        android:textColor="#5d5d5d" 
        android:textStyle="bold" > 
       </TextView> 

       <TextView 
        android:id="@+id/desciption" 
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content" 
        android:paddingBottom="2dip" 
        android:textColor="#000000" > 
       </TextView> 
      </LinearLayout> 
      <!-- Linear layout for cost and price Cost: Rs.100 --> 

      <LinearLayout 
       xmlns:android="http://schemas.android.com/apk/res/android" 
       android:layout_width="fill_parent" 
       android:layout_height="wrap_content" 
       android:orientation="horizontal" > 

       <!-- Cost Label --> 

       <TextView 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:gravity="left" 
        android:text="Phone: " 
        android:textColor="#5d5d5d" 
        android:textStyle="bold" > 
       </TextView> 
       <!-- Price Label --> 

       <TextView 
        android:id="@+id/cost" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:gravity="left" 
        android:textColor="#000000" 
        android:textStyle="bold" > 
       </TextView> 
      </LinearLayout> 

      <LinearLayout 
       xmlns:android="http://schemas.android.com/apk/res/android" 
       android:layout_width="fill_parent" 
       android:layout_height="wrap_content" 
       android:orientation="horizontal" > 

       <!-- Cost Label --> 

       <TextView 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:gravity="left" 
        android:text="Attraction: " 
        android:textColor="#5d5d5d" 
        android:textStyle="bold" > 
       </TextView> 
       <!-- Price Label --> 

       <TextView 
        android:id="@+id/sttraction" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:gravity="left" 
        android:textColor="#000000" 
        android:textStyle="bold" > 
       </TextView> 
      </LinearLayout> 
     </LinearLayout> 

    </LinearLayout> 


    this is main.xml 

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:ads="http://schemas.android.com/apk/lib/com.google.ads" 
    android:id="@+id/mainlayoutsecond" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:orientation="vertical" > 

    <LinearLayout 
     android:layout_width="fill_parent" 
     android:layout_height="fill_parent" 
     android:layout_weight=".1" 
     android:orientation="vertical" > 

     <ListView 
      android:id="@android:id/list" 
      android:layout_width="fill_parent" 
      android:layout_height="fill_parent" 
      android:cacheColorHint="#E3E3E3" 
      android:divider="#b5b5b5" 
      android:dividerHeight="1dp" 
      android:fastScrollEnabled="true" 
      android:focusable="false" /> 
    </LinearLayout> 
    </LinearLayout>
+0

我已经解析了xml。问题是“不在列表视图上显示”。 – emreturka

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