ListView使用自定義適配器

Question

我已經創建了一個Country.java類，並使我的自定義適配器myListAdapter擴展了ArrayAdapter。我沒有讓行，我既logcat中任何內留言，但應用程序崩潰：

countName.setText(" "+currentCountry.getCountryName()); 

究竟什麼是錯在這裏我怎樣才能得到國家或地區名稱？

public class Country{ 
    private String countryName; 
    private String capitalName; 

    public Country(String countryName, String capitalName) { 
    this.countryName = countryName; 
    this.capitalName = capitalName; 
} 

    public String getCountryName() { 
     return countryName; 
    } 
    public String getCapitalName() { 
     return capitalName; 
    } 
} 

這裏是類myListAdapter

private class MyListAdapter extends ArrayAdapter<Country>{ 

     public MyListAdapter() { 
      super(MainActivity.this, R.layout.item_view, myCountries); 
     } 

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

      View itemView = convertView; 
      if(itemView == null){ 
       itemView = getLayoutInflater().inflate(R.layout.item_view, parent, false); 
      } 

      Country currentCountry = myCountries.get(position); 

      TextView countName = (TextView) findViewById(R.id.item_countryName); 
      countName.setText(" "+currentCountry.getCountryName()); 

      TextView capName = (TextView) findViewById(R.id.item_CapName); 
      capName.setText(currentCountry.getCapitalName()); 

      return itemView; 
     } 
    } 

item_view.xml是：

<TextView 
     android:text="TextView" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/item_countryName" /> 

    <TextView 
     android:text="TextView" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/item_CapName" /> 

Answer 1

Change the below code in your adapter : 

TextView countName = (TextView) itemView.findViewById(R.id.item_countryName); 
      countName.setText(" "+currentCountry.getCountryName()); 

      TextView capName = (TextView) itemView.findViewById(R.id.item_CapName); 
      capName.setText(currentCountry.getCapitalName()); 

編輯我的代碼：

MyListAdapter adapter = new MyListAdapter(this, 
     R.layout.item_view, myCountries); 
listView.setAdapter(adapter); 

Answer 2

您是否手動啓動getView()方法？你應該如下所示@Override這個方法。如果您設置了適配器並且屏幕已加載，getView()會自動觸發。

@Override 
    public View getView(int i, View view, ViewGroup viewGroup) { 

    } 

你應該使用findViewById()方法如下;

TextView countName = (TextView) itemView.findViewById(R.id.item_countryName);