Android ArrayAdapter未将数据绑定到ListView
我正在尝试学习Android并构建一个非常基本的ListView,使用ArrayAdapter设置的数据没有显示出来。我的活动代码是: MainActivity类默认无更改 list_item_forecast.xml fragment_main.xml activity_main.xml 我所有的申请代码如上所述。我尝试过调整代码,也尝试过,但无法让它工作。请提供帮助。您设置的listview适配器不是您在片段中返回的listviewAndroid ArrayAdapter未将数据绑定到ListView,android,listview,android-fragments,android-arrayadapter,Android,Listview,Android Fragments,Android Arrayadapter,我正在尝试学习Android并构建一个非常基本的ListView,使用ArrayAdapter设置的数据没有显示出来。我的活动代码是: MainActivity类默认无更改 list_item_forecast.xml fragment_main.xml activity_main.xml 我所有的申请代码如上所述。我尝试过调整代码,也尝试过,但无法让它工作。请提供帮助。您设置的listview适配器不是您在片段中返回的listview 若你们在答案中添加一些解释,让用户知道为什么当前的代码片段
若你们在答案中添加一些解释,让用户知道为什么当前的代码片段不起作用,那个就更好了——若你们的阳光很小,它就起作用了。据我所知,这是与java对象概念相关的问题,如果您也能解释一下这里的错误,那会很有帮助。好的,我认为问题是没有返回使用setAdapter的View对象。fragment将在CreateView返回时显示View。您膨胀视图并在其中找到listview和setAdapter。但是您没有在CreateView中返回它。你给一辆新车充气,然后返回。
`public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}`
**MainActivityFragment class**
public class MainActivityFragment extends Fragment {
private ListAdapter arrayAdapter;
public MainActivityFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
ArrayList<String> myEntries = new ArrayList<String>();
myEntries.add("Unix");
myEntries.add("Java");
myEntries.add("Android");
arrayAdapter = new ArrayAdapter<String>(getActivity(), R.layout.list_item_forecast, R.id.list_forecast_item_textview, myEntries);
ListView listView = (ListView)inflater.inflate(R.layout.fragment_main, container, false).findViewById(R.id.list_view_forecast);
listView.setAdapter(arrayAdapter);
return inflater.inflate(R.layout.fragment_main, container, false);
}
}
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content" android:layout_height="wrap_content"
android:minHeight="?android:listPreferredItemHeight"
android:gravity="center_vertical"
android:text=""
android:id="@+id/list_forecast_item_textview">
</TextView>
<FrameLayout 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:showIn="@layout/activity_main"
tools:context=".MainActivityFragment"
android:id="@+id/forecastFragment">
<ListView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/list_view_forecast" />
<include layout="@layout/list_item_forecast" />
</FrameLayout>
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
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:fitsSystemWindows="true"
tools:context=".MainActivity">
<android.support.design.widget.AppBarLayout android:layout_height="wrap_content"
android:layout_width="match_parent" android:theme="@style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar android:id="@+id/toolbar"
android:layout_width="match_parent" android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary" app:popupTheme="@style/AppTheme.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
<include layout="@layout/content_main" />
<android.support.design.widget.FloatingActionButton android:id="@+id/fab"
android:layout_width="wrap_content" android:layout_height="wrap_content"
android:layout_gravity="bottom|end" android:layout_margin="@dimen/fab_margin"
android:src="@android:drawable/ic_dialog_email" />
</android.support.design.widget.CoordinatorLayout>
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
ArrayList<String> myEntries = new ArrayList<String>();
myEntries.add("Unix");
myEntries.add("Java");
myEntries.add("Android");
arrayAdapter = new ArrayAdapter<String>(getActivity(), R.layout.list_item_forecast, R.id.list_forecast_item_textview, myEntries);
View view =inflater.inflate(R.layout.fragment_main, container, false);
ListView listView = (ListView)view .findViewById(R.id.list_view_forecast);
listView.setAdapter(arrayAdapter);
return view ;
}