android新手，最近在学习 搜索sd卡上的所有txt文件并将其放入listview中显示，加载的过程中界面上会显示一个progress dialog。在之前的手机（Android5.0 android4.4）上都能正常的搜索到，但最近新换了一个手机（6.0） 发现logcat能够正常打印出路径 handle也能接收到搜索完成返回的message，但是没有扫描并放入listview 也没有显示progressdialog。求助

代码如下

package com.ldgforever.jianreader;  import java.io.File; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import com.ldgforever.savedata.savedataListMap; import android.app.Activity; import android.app.ProgressDialog; import android.content.DialogInterface; import android.content.Intent; import android.os.Bundle; import android.os.Environment; import android.os.Handler; import android.os.Message; import android.util.Log; import android.view.ActionMode; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.widget.AbsListView.MultiChoiceModeListener; import android.widget.AdapterView; import android.widget.AdapterView.OnItemClickListener; import android.widget.ListView; import android.widget.Toast;  public class BookListActivity extends Activity {      private static List<String> file_name;     private static List<String> file_txt_path;     private MyBookAdapter adapter;     private File file;     private List<Map<String, String>> listItems;     private MultiModeCallback mCallback;     private String mExternalStoragePath;     private Handler mHandler;     private ListView mListView;     private ProgressDialog mProgressDialog;      /**      * 接收返回的路径      */     @Override     protected void onActivityResult(int requestCode, int resultCode, Intent data) {         Log.d("com.ldgforever.jianreader", "receivingPath");         if (data != null) {             Log.d("com.ldgforever.jianreader", "onActivityResult");             ArrayList<String> mPath = data.getStringArrayListExtra("file");             for (int i = 0; i < mPath.size(); i++) {                 File pathFile = new File(mPath.get(i));                 Map<String, String> pathMap = new HashMap<String, String>();                 if (pathFile.exists()) {                     if (pathFile.getName().endsWith(".txt")) {                         pathMap.put("Name", pathFile.getName());                         pathMap.put("Path", pathFile.getPath());                         listItems.add(pathMap);                         savedataListMap.saveInfo(BookListActivity.this, "ListMap", listItems);                         ShowTxtFilesInList(listItems);                     } else {                         Toast.makeText(BookListActivity.this, "请选择一个txt文件！", 0).show();                         ;                     }                 }             }         }     }      @Override     protected void onCreate(Bundle bundle) {         super.onCreate(bundle);         setContentView(R.layout.activity_book_list);          mProgressDialog = new ProgressDialog(this);         mProgressDialog.setCancelable(false);         mProgressDialog.setMessage("正在搜索书籍，请稍候 ……");          mExternalStoragePath = Environment.getExternalStorageDirectory().toString();         Log.i("JianReader", mExternalStoragePath);         file = new File(mExternalStoragePath);          file_name = new ArrayList<String>();         file_txt_path = new ArrayList<String>();         listItems = new ArrayList<Map<String, String>>();          listItems = savedataListMap.getInfo(BookListActivity.this, "ListMap");         if (listItems.isEmpty()) {             listItems = new ArrayList<Map<String, String>>();             mProgressDialog.show();             new Thread() {                 public void run() {                     Log.i("JianReader", "listItem is Empty");                     listFileTxt(file);                     mHandler.sendEmptyMessage(11);                 }             }.start();         } else {             ShowTxtFilesInList(listItems);         }          mHandler = new Handler() {             public void handleMessage(Message message) {                 switch (message.what) {                 case 11:                     Log.i("JianReader", message.what + "");                     ShowTxtFilesInList(listItems);                     savedataListMap.saveInfo(BookListActivity.this, "ListMap", listItems);                     if (mProgressDialog.isShowing()) {                         mProgressDialog.dismiss();                         return;                     }                     break;                 case 12:                     Log.i("JianReader", message.what + "");                     ShowTxtFilesInList(listItems);                     savedataListMap.saveInfo(BookListActivity.this, "ListMap", listItems);                     if (mProgressDialog.isShowing()) {                         mProgressDialog.dismiss();                         return;                     }                     break;                 default:                     break;                 }                 return;             }         };     }      /**      * 书籍添加对话框      */     private void BookAddingDialog() {         android.app.AlertDialog.Builder builder = new android.app.AlertDialog.Builder(this);         builder.setTitle("请选择添加书籍的方式");         builder.setPositiveButton("扫描SDCard添加", new android.content.DialogInterface.OnClickListener() {             public void onClick(DialogInterface dialoginterface, int i) {                 listItems = new ArrayList<Map<String, String>>();                 mProgressDialog.show();                 new Thread() {                     public void run() {                         listFileTxt(file);                         mHandler.sendEmptyMessage(12);                     }                 }.start();             }         });         builder.setNegativeButton("选择路径添加", new android.content.DialogInterface.OnClickListener() {              public void onClick(DialogInterface dialoginterface, int i) {                  Intent intent = new Intent(BookListActivity.this, MyFileManager.class);                 startActivityForResult(intent, 2);             }         });         builder.setNeutralButton("稍后手动添加", new android.content.DialogInterface.OnClickListener() {              public void onClick(DialogInterface dialoginterface, int i) {                 dialoginterface.dismiss();             }          });         builder.create().show();     }      /**      * 将保存在List<Map<String,String>>中的书籍信息显示到ListView中      *       * @param listItems      */     private void ShowTxtFilesInList(final List<Map<String, String>> listItems) {         if (file_name != null) {             for (int i = 0; i < file_name.size(); i++) {                 HashMap<String, String> hashmap = new HashMap<String, String>();                 hashmap.put("Name", (String) file_name.get(i));                 hashmap.put("Path", (String) file_txt_path.get(i));                 listItems.add(hashmap);             }             adapter = new MyBookAdapter(this, listItems);             mCallback = new MultiModeCallback();             mListView = (ListView) findViewById(R.id.booklist);             mListView.setChoiceMode(3); // Multi             mListView.setOnItemClickListener(new OnItemClickListener() {                  @Override                 public void onItemClick(AdapterView<?> parent, View view, int position, long id) {                     Intent ii = new Intent(BookListActivity.this, ReadingActivity.class);                     String itemPath = listItems.get(position).get("Path");                     ii.putExtra("mItemPath", itemPath);                     startActivity(ii);                 }             });             mListView.setMultiChoiceModeListener(mCallback);             mListView.setAdapter(adapter);         } else {             failAddingDialog();             return;         }     }      /**      * 添加书籍失败对话框      */     private void failAddingDialog() {         android.app.AlertDialog.Builder builder = new android.app.AlertDialog.Builder(this);         builder.setTitle("添加书籍失败");         builder.setPositiveButton("确定", new android.content.DialogInterface.OnClickListener() {             public void onClick(DialogInterface dialoginterface, int i) {                 dialoginterface.dismiss();             }         });     }      /**      * 递归查找SD卡上所有书籍      *       * @param file      */     public static void listFileTxt(File file) {         File[] files = file.listFiles();          try {             for (File f : files) {                 if (!f.isDirectory()) {                     if (f.getName().endsWith(".txt")) {                         long size = f.length();                         if (size > 50 * 1024) {                             file_name.add(f.getName());                             file_txt_path.add(f.getAbsolutePath());                         }                     }                 } else if (f.isDirectory()) {                     listFileTxt(f);                 }             }         } catch (Exception e) {             // TODO Auto-generated catch block             e.printStackTrace();         }     } 

logcat无报错
我试了默认存储位置为机身和SD卡，均不能加载