Question

我是Android新手。我试图使用片段上的适配器从应用程序中的String数组显示一个简单的预测。它没有出现在窗户上。我已经定义了2个类（MainActivity和MainActivityFragment）。我使用的是Android Studio 2.1.3。

如果我在activity_mail.xml中使用片段而不是ListView，则会给我一个stackoverflow错误。
如果我在activity_mail.xml上使用ListView，它就不会出现。

任何帮助，都会非常感激

这是我的代码：

a）MainActivity.java

    package app.com.example.android.sunshine3;

    import android.os.Bundle;
    import android.support.v7.app.AppCompatActivity;

    public class MainActivity extends AppCompatActivity {
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
        }
    }

b）MainActivityFragment.java

    package app.com.example.android.sunshine3;

    import android.app.Fragment;
    import android.os.Bundle;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.ArrayAdapter;
    import android.widget.ListView;

    import java.util.ArrayList;
    import java.util.Arrays;
    import java.util.List;


    public class MainActivityFragment extends Fragment {

    public MainActivityFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        ArrayAdapter<String> mForecastAdapter;

        // Create some dummy data for the ListView.  Here's a sample weekly forecast
        String[] data = {
                "Mon 6/23 - Sunny - 31/17",
                "Tue 6/24 - Foggy - 21/8",
                "Wed 6/25 - Cloudy - 22/17",
                "Thurs 6/26 - Rainy - 18/11",
                "Fri 6/27 - Foggy - 21/10",
                "Sat 6/28 - TRAPPED IN WEATHERSTATION - 23/18",
                "Sun 6/29 - Sunny - 20/7"
        };
        List<String> weekForecast = new ArrayList<String>(Arrays.asList(data));


        // Now that we have some dummy forecast data, create an ArrayAdapter.
        // The ArrayAdapter will take data from a source (like our dummy forecast) and
        // use it to populate the ListView it's attached to.
        mForecastAdapter =
                new ArrayAdapter<String>(
                        getActivity(), // The current context (this activity)
                        R.layout.list_item_forescast, // The name of the layout ID.
                        R.id.list_item_forecast_textview, // The ID of the textview to populate.
                        weekForecast);

        // Inflate the root layout for this fragment
        View rootView = inflater.inflate(R.layout.activity_main, container, false);

        // Get a reference to the ListView, and attach this adapter to it.

        ListView listView = (ListView) rootView.findViewById(R.id.fragment);
        listView.setAdapter(mForecastAdapter);

        return rootView;

    }
    }

c）activity_main.xml：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="app.com.example.android.sunshine3.MainActivity">

    <ListView xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/fragment"
        android:name="app.com.example.android.sunshine3.MainActivityFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</RelativeLayout>

d）list_item_forescast.xml：

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

        android:id="@+id/list_item_forecast_textview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center_vertical"
        android:minHeight="?android:attr/listPreferredItemHeight"></TextView>

Answer 1

问题是您并没有真正使用您的片段，因为您没有在activity中添加它。一个简单的解决方法是为您的活动定义一个独立的布局：

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

</FrameLayout>

现在，在您的活动中，将fragment添加到此容器中：

setContentView(R.layout.home_activity_layout);

MainActivityFragment myFragment = new MainActivityFragment();
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction().add(R.id.fragment_container, myFragment, MainActivityFragment.class.getName()).commit();

应该这样做。

带有Fragment的适配器无法在Android Studio中运行

1 个答案: