应用程序已连接到Web服务: - 提取并解析xml - >作品 - 适配器 - >作品
但是当我使用findViewById()初始化ListView(lstCustomers)时为null并且我不明白为什么?
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
String url = "myUrl.com";
Log.d("CustomerREST", "Start Activity");
try {
RestCustomerAsync ctm = new RestCustomerAsync();
ctm.execute(url);
ArrayList<Customer> ctms = (ArrayList<Customer>) ctm.get();
//CustomerAdapter adapter = new CustomerAdapter(this,R.layout.customer_row,ctms);
CustomerAdapter adapter = new CustomerAdapter(getApplicationContext(), R.layout.customer_row, ctms);
Log.d("CustomerREST", "Adapter OK");
ListView lstCustomer = (ListView) findViewById(R.id.lstCustomers); // return null why ??
Log.d("CustomerREST", "INIT LISTVIEW");
lstCustomer.setAdapter(adapter);
Log.d("CustomerREST", "Adapter to View");
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
XML布局
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context=".MainActivity">
<ListView
android:id="@+id/lstCustomers"
android:layout_width="match_parent"
android:layout_height="match_parent" />
答案 0 :(得分:0)
如果您的代码是片段:
在实际创建视图之前触发onCreate 。
请将您的代码移至 onViewCreated()方法,如下所示:
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
//here Your code.
}
如果您的代码在Activity中:
setContentView(R.your_layout)
在 onCreate 方法内。
答案 1 :(得分:0)
我想您可能忘记致电setContentView(R.layout.your_layout)