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