Question

我创建了一个Country.java类，并使我的自定义适配器myListAdapter扩展了ArrayAdapter。我的LogCat中没有任何消息，但是应用程序崩溃了：

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

所以这里有什么问题我怎么能得到CountryName？

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;
    }
}

这里是myListAdapter类

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());

编辑我的代码：

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

Answer 2

您是手动触发getView()方法吗？您应该@Override此方法如下所示。如果您设置了适配器并且加载了屏幕，则会自动触发getView()。

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

    }

您应该使用下面的findViewById()方法;

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

ListView使用自定义适配器

2 个答案: