我正在尝试运行以下代码:
public class MyListActivity extends ListActivity {
private static class MyListLoadingCallback implements Handler.Callback {
private ListActivity activity;
private MyListManager myListManager;
public MyListLoadingCallback(ListActivity activity,
MyListManager articleListManager) {
this.activity = activity;
this.myListManager = myListManager;
}
@Override
public boolean handleMessage(Message message) {
throw new NotYetImplementedException();
}
}
private MyListManager myListManager;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
myListManager.fetchArticles(new Handler(
new MyListLoadingCallback(this, MyListManager)));
}
我在articleListManager.fetchArticles(new Handler(new MyListLoadingCallback(this, MyListManager)));处得到一个空指针
我的其他类(class)如下所示:
public class MyListManager {
public void fetchArticles(final Handler handler) {
}
}
有人可以带我/帮助我处理这段代码以便更好地理解吗?我似乎还没有完全理解它。
最佳答案
错误似乎很清楚:)。
在抛出异常的行中只有一个“引用”被访问 (myListManager.fetchArticles(new Handler(new MyListLoadingCallback(this, MyListManager)));
),它是 >myListManager
,所以它必须是NULL
。查看代码,您永远不会将其初始化为任何内容,因此它确实是 NULL
:)
关于java - 返回空指针的处理程序,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/27434896/