2017-06-17 55 views
0

我是Android新手。我创建了一个导航抽屉并在其中制作了菜单,并添加了碎片。现在为每个菜单我想用arrayadapter类创建一个自定义列表视图。我实现了它,但问题是标题和地址在列表中的每一项中都是一样的。该列表仅显示最后一个项目。任何人都可以帮助我!我找不出解决方案。下面是一些代码和照片:Listview显示最后一个项目的标题和地址,列表中的所有项目

import static com.example.user.appsightseeing.R.layout; 



public class ParksFragment extends Fragment { 
    private ArrayList<Park> parks = new ArrayList<>(); 


    public ParksFragment() { 
     // Required empty public constructor 
    } 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 

     View rootView = inflater.inflate(layout.fragment_parks, container, false); 

     parks.add(new Park("Artificial Lake of Tirana", "The Grand Park of Tirana, also known as the Tirana Park on the Artificial Lake or even the Park of Saint Procopius, is a 230 hectare public park situated on the southern part of Tirana.", 
       "At the end of Rruga Sami Frasheri.", R.drawable.artificiallake)); 
     parks.add(new Park("Zoo park", "The only one of its kind in Albania, Tirana Zoo is concentrated in an area of \u200B\u200B7 hectares in the southern part of town, between the Grand Park and the Botanic Garden of Tirana . The zoo was established in 1966.", 
       "Near Rruga Liqeni i Thate", R.drawable.zoopark)); 
     parks.add(new Park("Memorial park of the Cemetery of the Nation's Martyrs", "The National Martyrs Cemetery of Albania is the largest cemetery in Albania, located on a hill overlooking Tirana. The \"Mother Albania\" statue is located at the Cemetery.", 
       "Near street Rruga Ligor Lubonja", R.drawable.memorialpark)); 
     parks.add(new Park("Kashar park", "The main core of Kashar’s Park, is the Reservoir of Purez- Kus. The reservoir and its surrounding territory are considered as one of the most picturesque and biologically unsoiled suburbs of Tirana.", 
       "Kashar", R.drawable.kasharpark)); 
     parks.add(new Park("Vaqarr park", "The second park in Vaqarr, is a recreational area of 97 ha, that is more than useful to inhabitants in Tirana.", 
       "Vaqarr", R.drawable.vaqarripark)); 
     parks.add(new Park("Farka Lake park", "To the East of the East of Tirana’s city center, Lake Farka is a local favorite for waterborne fun in Summer. Picnicking, jet and water skiing, swimming, boating, all the usual wet sports suspects.", 
       "At Lake of Farka, near Rruga Pjeter Budi", R.drawable.farkapark)); 
     parks.add(new Park("Peza park", "Peza, a village approximately 20 minutes from the center of Tirana, is a popular place for locals to go for a coffee or lunch on the weekends to escape the city.", 
       "Peze", R.drawable.pezapark)); 
     parks.add(new Park("Dajti Recreative park", "This park is one of the components of Dajti National Park, located 26 km east of Tirana and 50 km from \"Mother Teresa\" airport. This place is very frequented by tourists and is also known as the \"Natural Balcon of Tirana\" which offers recreation and accommodation facilities for tourists.", 
       "Dajti mountain", R.drawable.dajtirecreative)); 
     parks.add(new Park("Dajti National park", "Dajti National Park is very important on local, national and regional level, for its biodiversity, landscape, recreational and cultural values. Among others it is considered as a live museum of the natural vertical structure of vegetation.", 
       "Dajti mountain", R.drawable.dajtinational)); 
     parks.add(new Park("Botanic garden", "The Botanical Gardens of Tirana are scenic botanical gardens located in southern Tirana, Albania. It is the only botanical garden in Albania. Construction commenced in 1964, with the original site covering approximately 15 hectares.", 
       "Near Zoo park", R.drawable.botanicpark)); 
     parks.add(new Park("Rinia park", "The park, 500 metres (1,600 ft) from the central square, was built in 1950[5] as part of a major urban development program which developed after World War II. It was initially a pleasant family park where inhabitants of Tirana could take their children.", 
       "Near Bulevardi Deshmoret e Kombit and near Rruga Myslym Shyri", R.drawable.riniapark)); 

     ArrayAdapter<Park> adapter = new parkArrayAdapter(getActivity(), 0, parks); 


     ListView listView = (ListView) rootView.findViewById(R.id.customListView); 
     listView.setAdapter(adapter); 
     return rootView; 

     //add event listener so we can handle clicks 
    } 

    @Override 
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) { 

     super.onViewCreated(view, savedInstanceState); 
    } 
} 

一个ArrayAdapter类:

import java.util.List; 



    public class parkArrayAdapter extends ArrayAdapter<Park> { 

     private Context context; 
     private List<Park> parks; 
     private AnimatedStateListDrawable inflater; 

     //constructor, call on creation 
     public parkArrayAdapter(Context context, int resource, ArrayList<Park> objects) { 
      super(context, resource, objects); 

      this.context = context; 
      this.parks = objects; 
     } 

     //called when rendering the list 
     @NonNull 
     public View getView(int position, View convertView, ViewGroup parent) { 


      //get the park we are displaying 
      Park par = parks.get(position); 
      //get the inflater and inflate the XML layout for each item 
      LayoutInflater inflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE); 
      View view = inflater.inflate(R.layout.park_layout, null); 

      TextView title = (TextView) view.findViewById(R.id.p_title); 
      TextView description = (TextView) view.findViewById(R.id.p_description); 
      TextView streetname = (TextView) view.findViewById(R.id.address); 
      ImageView image = (ImageView) view.findViewById(R.id.image); 

      //set title and description 
      String titleT = par.getPark_title(); 
      title.setText(titleT); 

      //display trimmed excerpt for description 
      int descriptionLength = par.getPark_description().length(); 
      if(descriptionLength >= 100){ 
       String descriptionTrim = par.getPark_description().substring(0, 100) + "..."; 
       description.setText(descriptionTrim); 
      }else{ 
       description.setText(par.getPark_description()); 
      } 

      streetname.setText(par.getPark_streetname()); 

      //get the image associated with this park 
      int imageID = context.getResources().getIdentifier(String.valueOf(par.getPark_image()), "drawable", context.getPackageName()); 
      image.setImageResource(imageID); 

      return view; 
     } 
    } 

园区类:

public class Park { 

    private static String title; 
    private String description; 
    private static String streetname; 
    private int image; 


    public Park(String title, String description, String streetname, int image){ 
     this.title = title; 
     this.description = description; 
     this.streetname = streetname; 
     this.image = image; 

    } 

    public static String getPark_title() { return title; } 

    public String getPark_description() { 
     return description; 
    } 

    public static String getPark_streetname() { 
     return streetname; 
    } 

    public int getPark_image() { 
     return image; 
    } 
} 

公园布局中的一行:

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:orientation="vertical" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:paddingTop="10dp" 
    android:paddingBottom="10dp"> 

    <ImageView 
     android:id="@+id/image" 
     android:layout_width="100dp" 
     android:layout_height="100dp" 
     android:layout_marginRight="10dp" 
     android:contentDescription="Park Image" /> 

    <LinearLayout 
     android:id="@+id/infoSection" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:layout_toRightOf="@+id/image" 
     android:orientation="vertical"> 

     <TextView 
      android:id="@+id/p_title" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:layout_marginBottom="10dp" 
      android:text="Park Title" 
      android:textColor="@android:color/black" 
      android:textSize="18sp" /> 

     <TextView 
      android:id="@+id/p_description" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:layout_marginBottom="10dp" 
      android:layout_marginRight="5dp" 
      android:text="Park Description" 
      android:textColor="@android:color/black" 
      android:textSize="15sp" /> 

    </LinearLayout> 

    <RelativeLayout 
     android:id="@+id/addressSection" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:layout_below="@+id/infoSection" 
     android:orientation="vertical" 
     android:layout_alignParentBottom="true"> 

     <TextView 
      android:id="@+id/address" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:layout_marginBottom="2dp" 
      android:text="Address:" 
      android:textColor="@android:color/black" /> 

    </RelativeLayout> 

</RelativeLayout> 

screenshot of the listview with same titles and addresses in all items

回答

0

这是不与Android有关。如果你检查你的班级,你会看到你描述的标题和街道名称字段和他们的getter方法是静态的。您面临这个问题,因为当您从适配器获得价值时,所有标题和街道名称字段都相同。您已经为描述任何平台上任何应用程序中静态成员和实例成员之间的差异提供了一个很好的示例实例成员位于内存的不同地址,但静态成员位于相同地址,并且当您为静态成员分配值时,则所有静态成员的值都会更改,因为它们位于内存中的相同位置。当你删除“静态”单词时,你的列表视图会很好地工作。

+0

非常感谢您的详细解释!现在我明白了我没有注意到的区别。 –

+0

欢迎您。很高兴阅读您的评论。最好的教训带来了良好的错误,你永远不会忘记静态和实例成员问题。 – CanDroid

+0

您可以给我一个提示,说明如何为我的列表项目实现onItemClickedListener,并开始一个新的活动或一个新的片段(我不确定)与该项目的细节。在一个片段中实现listview会让我感到困惑,因为它与实现活动的方式不同。我不知道你是否可以帮忙..在此先感谢! –

0

由于您使用静态变量删除从公园类的标题和streetname静态

private String title; 
private String streetname; 

Java中的static关键字意味着该变量或函数是类的所有实例之间共享因为它属于类型,而不是实际的对象本身。

+0

非常感谢您的帮助!让我的一天! –

0

删除静态类公园领域冠军streetname

此外,类应该大写,所以ParkArrayAdapter,不parkArrayAdapter

+0

非常感谢!其实我已经宣布他们静态在开始,但由于一些Java的建议,我将它们改为静态。然后感到困惑,看不出有什么不同。现在我明白了为什么我的描述和图像工作正常。这一切都完美!谢谢 !! –

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