我正在关注MVP设计模式。我从View中调用Presenter中的方法,该方法为网络请求执行异步任务。到目前为止我已经调试过,它成功地将JSON作为String返回,但是当我想将它传递给从Presenter到View的方法时,我得到了这个错误:
尝试调用虚拟方法' android.view.View android.view.Window.findViewById(int)'在空对象引用上
这是我的代码:
查看:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_mediated);
TextView welcome_txt = (TextView) findViewById(R.id.welcome_txtview);
MediatedPresenter mediatedPresenter = new MediatedPresenter();
mediatedPresenter.createConnection();
}
public void getResult(String result)
{
TextView welcome_txt = (TextView) findViewById(R.id.welcome_txtview);
welcome_txt.setText(result);
}
主讲人:
public void createConnection() {
new NetworkRequest(new ResultFromAsync() {
@Override
public void taskCompleted(String result) {
MediatedActivity mediatedActivity = new MediatedActivity();
mediatedActivity.getResult(result);
}
}).execute();
}
XML:
<RelativeLayout 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="uk.co.bbc.avtestharnesssmp.MediatedActivity"
android:background="#3498db">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Welcome"
android:id="@+id/welcome_txtview"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:textColor="#80ffffff" />
</RelativeLayout>
BTW:我在这一行得到了错误&#34; mediatedActivity.getResult(result);&#34;只是为了澄清我试图将taskCompleted的结果发送到View中的getResult方法。
有谁知道我做错了什么?