java.lang.NullPointerException:尝试使用BaseAdapter调用虚拟方法'int android.view.View.getImportantForAccessibility()' [英] java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' using BaseAdapter
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问题描述
如何使用BaseAdapter从SDcard的文件夹中获取mp3文件并在自定义列表视图中显示，以及如何在Item Click上播放歌曲.
How to get mp3 files from a folder in SDcard and show in custom listview using BaseAdapter and also want to play the song on Item Click.
我正在使用基本适配器从SDCard特定文件夹中获取mp3文件.正在获取mp3文件，但无法添加到自定义基本适配器中. 我收到此异常:
I am getting the mp3 files from a SDCard particular folder using base adapter.Getting the mp3 files but unable to add to custom base Adapter. I am getting this exception :
java.lang.NullPointerException:尝试调用虚拟方法'int 空对象上的android.view.View.getImportantForAccessibility()' 使用BaseAdapter进行引用.
java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference using BaseAdapter.
下面是我的片段:
ListView lv_recordersList;
private ListViewAdapter adapter;
ProgressDialog mProgressDialog;
private List<String> myList;
File file;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
View v = inflater.inflate(R.layout.frag_recorders_list, null);
lv_recordersList = (ListView) v.findViewById(R.id.lv_recordersList);
myList = new ArrayList<String>();
new DownloadJSON().execute();
return v;
}
public class DownloadJSON extends AsyncTask<Void, Void, Void>{
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
mProgressDialog = new ProgressDialog(getActivity());
//mProgressDialog.setTitle("PlugLeads");
mProgressDialog.setMessage("Loading...");
mProgressDialog.setIndeterminate(false);
mProgressDialog.show();
}
@Override
protected Void doInBackground(Void... params) {
// TODO Auto-generated method stub
File directory = Environment.getExternalStorageDirectory();
file = new File(directory + "/Plugleads");
File list[] = file.listFiles();
for (int i = 0; i < list.length; i++) {
// if(checkExtension( list[i].getName())
if (checkExtension(list[i].getName())) {
myList.add(list[i].getName());
}
}
return null;
}
@Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
//listview = (ListView) findViewById(R.id.listview);
// Pass the results into ListViewAdapter.java
adapter = new ListViewAdapter(getActivity(), myList);
// Set the adapter to the ListView
lv_recordersList.setAdapter(adapter);
// Close the progressdialog
mProgressDialog.dismiss();
}
private boolean checkExtension(String fileName) {
String ext = getFileExtension(fileName);
if (ext == null)
return false;
try {
if (SupportedFileFormat.valueOf(ext.toUpperCase()) != null) {
return true;
}
} catch (IllegalArgumentException e) {
return false;
}
return false;
}
public String getFileExtension(String fileName) {
int i = fileName.lastIndexOf('.');
if (i > 0) {
return fileName.substring(i + 1);
} else
return null;
}
}
这是我的CustomBaseAdapter
This is my CustomBaseAdapter
public class ListViewAdapter extends BaseAdapter{
Context context;
LayoutInflater inflater;
private List<String> myListp;
public ListViewAdapter(Context context,
List<String> myList) {
this.context = context;
myListp= myList;
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return myListp.size();
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return myListp.get(position);
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
ImageView img_recorders_listitem;
TextView tv_recorders_listitem;
inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View itemView = inflater.inflate(R.layout.frag_recorders_listitem, parent, false);
img_recorders_listitem = (ImageView) itemView.findViewById(R.id.img_recorders_listitem);
tv_recorders_listitem = (TextView) itemView.findViewById(R.id.tv_recorders_listitem);
return convertView;
}
我的Logcat
06-09 10:30:43.378: E/AndroidRuntime(21491): FATAL EXCEPTION: main
06-09 10:30:43.378: E/AndroidRuntime(21491): Process: com.plugleads.feedbackform, PID: 21491
06-09 10:30:43.378: E/AndroidRuntime(21491): java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.AbsListView.obtainView(AbsListView.java:2363)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.ListView.makeAndAddView(ListView.java:1864)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.ListView.fillDown(ListView.java:698)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.ListView.fillFromTop(ListView.java:759)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.ListView.layoutChildren(ListView.java:1673)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.AbsListView.onLayout(AbsListView.java:2151)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.View.layout(View.java:15689)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.ViewGroup.layout(ViewGroup.java:5040)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.View.layout(View.java:15689)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.ViewGroup.layout(ViewGroup.java:5040)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.FrameLayout.layoutChildren(FrameLayout.java:579)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.FrameLayout.onLayout(FrameLayout.java:514)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.View.layout(View.java:15689)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.ViewGroup.layout(ViewGroup.java:5040)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:1043)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.View.layout(View.java:15689)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.ViewGroup.layout(ViewGroup.java:5040)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.FrameLayout.layoutChildren(FrameLayout.java:579)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.FrameLayout.onLayout(FrameLayout.java:514)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.View.layout(View.java:15689)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.ViewGroup.layout(ViewGroup.java:5040)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.support.v7.internal.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:437)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.View.layout(View.java:15689)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.ViewGroup.layout(ViewGroup.java:5040)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.FrameLayout.layoutChildren(FrameLayout.java:579)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.FrameLayout.onLayout(FrameLayout.java:514)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.View.layout(View.java:15689)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.ViewGroup.layout(ViewGroup.java:5040)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.View.layout(View.java:15689)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.ViewGroup.layout(ViewGroup.java:5040)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.FrameLayout.layoutChildren(FrameLayout.java:579)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.widget.FrameLayout.onLayout(FrameLayout.java:514)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.View.layout(View.java:15689)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.ViewGroup.layout(ViewGroup.java:5040)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2116)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1873)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1084)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5990)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.Choreographer.doCallbacks(Choreographer.java:580)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.Choreographer.doFrame(Choreographer.java:550)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.os.Handler.handleCallback(Handler.java:739)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.os.Handler.dispatchMessage(Handler.java:95)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.os.Looper.loop(Looper.java:135)
06-09 10:30:43.378: E/AndroidRuntime(21491): at android.app.ActivityThread.main(ActivityThread.java:5343)
06-09 10:30:43.378: E/AndroidRuntime(21491): at java.lang.reflect.Method.invoke(Native Method)
06-09 10:30:43.378: E/AndroidRuntime(21491): at java.lang.reflect.Method.invoke(Method.java:372)
06-09 10:30:43.378: E/AndroidRuntime(21491): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:905)
06-09 10:30:43.378: E/AndroidRuntime(21491): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:700)
请帮助我.提前进行提醒...
Please Help me.Thaks in advance...
推荐答案
您的getView()方法返回null更改以下代码.
your getView() method return null change the below code.
更改此
return convertView;
对此
return itemView;
更新:只是我正在使用适用于我的代码来获取文件名.
Update : simply I am using this code that work for me to get the name of file.
File file = new File("/storage/sdcard0/abc.mp3");
String strFileName = file.getName();
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