Question

我是android新手，一直关注udacity的视频讲座。列表视图不会被数组适配器和何时填充我在移动设备上运行应用程序，应用程序只显示了主要的活动布局。

列表视图没有出现在手机屏幕上，任何人都可以告诉我这里的错误是什么，它是与帧布局相关的还是有一个错误数组适配器。提前致谢

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

}
public static class PlaceHolderFragment extends Fragment {
    private ArrayAdapter<String> mForecastAdapter;
    public PlaceHolderFragment(){}
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
       View rootview= inflater.inflate(R.layout.fragment_main, container, false);
        String[] forecastArray={
                "Today","Tommorow","wed","Thursday","Friday","Saturday","Sunday"
        };//creating some fake data to show in list view
        List<String> fore=new ArrayList<String>(Arrays.asList(forecastArray));
        mForecastAdapter=new ArrayAdapter<String>(getActivity(),R.layout.list_item_forecast,R.id.list_item_forecast_textview,fore);
        ListView listview= (ListView)rootview.findViewById(R.id.listview_forecast);
        listview.setAdapter(mForecastAdapter);
        return rootview;

    }
}
}

activity_main_xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/container"
tools:context="com.saxenarc.jeetesh.layouts.MainActivity">
</FrameLayout>

list_item_forecast.xml

<?xml version="1.0" encoding="utf-8"?>

<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="wrap_content"
android:id="@+id/list_item_forecast_textview"
android:minHeight="?android:attr/listPreferredItemHeight"
android:gravity="center_vertical"
>

</TextView>

fragment_main.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android" 
android:layout_width="match_parent"
android:layout_height="match_parent">

<ListView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/listview_forecast"></ListView>

</FrameLayout>

在发布之前检查所有内容三次。

Answer 1

您的代码和列表运行良好，但您尚未告知列表要显示的位置。您可以通过两种方式解决此问题。

<强>第一

在主要活动中添加片段，因为它不可见。

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
        fragmentManager.beginTransaction().replace(R.id.container, new PlaceHolderFragment).commit();
    }

<强>第二

停止使用片段并使用主要活动

中的列表视图

activity_main.xml中

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android" 
android:layout_width="match_parent"
android:layout_height="match_parent">

<ListView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/listview_forecast"></ListView>

</FrameLayout>

MainActivity.java

List<String> fore = new ArrayList<String>(Arrays.asList(forecastArray));
mForecastAdapter = new ArrayAdapter<String>(this,R.layout.list_item_forecast,R.id.list_item_forecast_textview,fore);
ListView listview= (ListView) findViewById(R.id.listview_forecast);
listview.setAdapter(mForecastAdapter);

列表视图未被阵列适配器填充

1 个答案: