应用程序在模拟器上运行良好，但在真实设备上崩溃
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【中文标题】应用程序在模拟器上运行良好，但在真实设备上崩溃【英文标题】：App runs fine on emulator, but crashes on real device 【发布时间】：2015-07-26 23:27:55 【问题描述】：我尝试过做一个解析 xml 文件的应用程序。在模拟器中运行良好，但是当我在真机、安卓手机和安卓平板电脑上运行它时，它就崩溃了……
这是 MainActivity.java
public class MainActivity extends ActionBarActivity
public List<UnitModel> model = null;
private String filename = "ModelInfo.txt";
UnitModelParser parser = new UnitModelParser();
public List<Gps> coordinate = new ArrayList<Gps>();
private String fName;
GpsXmlParser gpsParser = new GpsXmlParser();
ArrayList<Gps> coorList = gpsParser.getItemsList();
String TAG = "Test";
private static final String FOLDER_PATH = Environment.getExternalStorageDirectory() + "/Gps/";
File dir = new File (FOLDER_PATH);
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
new LoadModelTask().execute();
Button btnModel = (Button) findViewById(R.id.btnModel);
btnModel.setOnClickListener(new OnClickListener()
public void onClick(View v)
// write on SD card file data in the text box
if (isWritable())
ArrayList<UnitModel> modelList = parser.getItemsList();
UnitModel modd = modelList.get(0);
StringBuilder locationStrBuilder = new StringBuilder();
locationStrBuilder.append(modd);
String locationStrModel = locationStrBuilder.toString();
fName = locationStrModel + ".txt";
try
File sdCard = Environment.getExternalStorageDirectory();
File directory = new File(sdCard.getAbsolutePath()+"/GpsOutput");
directory.mkdirs();
File myFile = new File(directory, filename);
myFile.createNewFile();
FileOutputStream fOut = new FileOutputStream(myFile, true);
OutputStreamWriter myOutWriter = new OutputStreamWriter(fOut);
myOutWriter.append(locationStrModel + "\n");
myOutWriter.close();
fOut.close();
Toast.makeText(getBaseContext(),"Successfully acquired the unit information.",Toast.LENGTH_SHORT).show();
System.out.println("Model ID : " + locationStrModel);
catch (Exception e)
Toast.makeText(getBaseContext(), e.getMessage(),Toast.LENGTH_SHORT).show();
else
Toast.makeText(getBaseContext(),"SD Card Not Available",Toast.LENGTH_SHORT).show();
);
new LoadGpsTask().execute();
Button btnGps = (Button) findViewById(R.id.btnGps);
btnGps.setOnClickListener(new OnClickListener()
@Override
public void onClick(View v)
StringBuilder locationStrBuilder = new StringBuilder();
int s = 0;
for (Gps c : coordinate)
locationStrBuilder.append(c.toString());
System.out.println(++s + c.toString());
if (isWritable())
try
File sdCard = Environment.getExternalStorageDirectory();
File directory = new File(sdCard.getAbsolutePath()+"/GpsOutput");
directory.mkdirs();
File myFile = new File(directory, fName);
myFile.createNewFile();
FileOutputStream fOut = new FileOutputStream(myFile, false);
OutputStreamWriter myOutWriter = new OutputStreamWriter(fOut);
myOutWriter.append(locationStrBuilder);
myOutWriter.close();
fOut.close();
Toast.makeText(getBaseContext(),"Successfully downloaded gps coordinate.",Toast.LENGTH_SHORT).show();
catch (Exception e)
Toast.makeText(getBaseContext(), e.getMessage(),Toast.LENGTH_SHORT).show();
else
Toast.makeText(getBaseContext(),"SD Card Not Available",Toast.LENGTH_SHORT).show();
);
// onCreate
private class LoadModelTask extends AsyncTask<String, Void, List<UnitModel>>
@Override
protected List<UnitModel> doInBackground(String... args)
// CALL XMLPULLPARSER & RETURN A LIST
model = parser.parse(getBaseContext());
return model;
//filenamefilter method
public FilenameFilter xmlFilter = new FilenameFilter()
@Override
public boolean accept(File dir, String name)
return name.endsWith(".xml") || name.endsWith(".XML");
;
private class LoadGpsTask extends AsyncTask<String, Void, List<Gps>>
@Override
protected List<Gps> doInBackground(String... args)
// CALL XMLPULLPARSER & RETURN A LIST
String files[] = dir.list(xmlFilter);
for (String filename : files)
String path = dir.getAbsolutePath() + "/" + filename;
Log.i(TAG, path);
System.out.println("PARSING : " + path);
coordinate.addAll(gpsParser.parse(path));
Log.i(TAG,"message");
Log.i(TAG,coordinate.size() + "");
Log.i(TAG,coordinate.size() + "");
return coordinate;
public boolean isWritable()
String status = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(status))
return true;
return false;
//isWritable
这是 logcat 的输出：
05-15 14:03:35.016: E/androidRuntime(2942): FATAL EXCEPTION: AsyncTask #2
05-15 14:03:35.016: E/AndroidRuntime(2942): java.lang.RuntimeException: An error occured while executing doInBackground()
05-15 14:03:35.016: E/AndroidRuntime(2942): at android.os.AsyncTask$3.done(AsyncTask.java:299)
05-15 14:03:35.016: E/AndroidRuntime(2942): at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
05-15 14:03:35.016: E/AndroidRuntime(2942): at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
05-15 14:03:35.016: E/AndroidRuntime(2942): at java.util.concurrent.FutureTask.run(FutureTask.java:239)
05-15 14:03:35.016: E/AndroidRuntime(2942): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
05-15 14:03:35.016: E/AndroidRuntime(2942): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
05-15 14:03:35.016: E/AndroidRuntime(2942): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
05-15 14:03:35.016: E/AndroidRuntime(2942): at java.lang.Thread.run(Thread.java:838)
05-15 14:03:35.016: E/AndroidRuntime(2942): Caused by: java.lang.NullPointerException
05-15 14:03:35.016: E/AndroidRuntime(2942): at asp.xmlreader.MainActivity$LoadGpsTask.doInBackground(MainActivity.java:152)
05-15 14:03:35.016: E/AndroidRuntime(2942): at asp.xmlreader.MainActivity$LoadGpsTask.doInBackground(MainActivity.java:1)
05-15 14:03:35.016: E/AndroidRuntime(2942): at android.os.AsyncTask$2.call(AsyncTask.java:287)
05-15 14:03:35.016: E/AndroidRuntime(2942): at java.util.concurrent.FutureTask.run(FutureTask.java:234)
05-15 14:03:35.016: E/AndroidRuntime(2942): ... 4 more
05-15 14:03:35.041: V/InputMethodManager(2942): onWindowFocus: null softInputMode=288 first=true flags=#1810100
05-15 14:03:35.042: V/InputMethodManager(2942): START INPUT: com.android.internal.policy.impl.PhoneWindow$DecorView41377878 V.E..... R.....ID 0,0-768,976 ic=null tba=android.view.inputmethod.EditorInfo@413a1d28 controlFlags=#104
05-15 14:03:35.044: V/InputMethodManager(2942): Starting input: Bind result=InputBindResultcom.android.internal.view.IInputMethodSession$Stub$Proxy@413a2678 com.google.android.inputmethod.latin/com.android.inputmethod.latin.LatinIME #16
05-15 14:03:36.076: D/OpenGLRenderer(2942): Flushing caches (mode 0)
05-15 14:03:36.174: D/OpenGLRenderer(2942): Flushing caches (mode 0)
05-15 14:03:36.178: D/OpenGLRenderer(2942): Flushing caches (mode 1)
05-15 14:03:36.183: D/OpenGLRenderer(2942): Flushing caches (mode 0)
05-15 14:03:38.085: I/Process(2942): Sending signal. PID: 2942 SIG: 9
谁能告诉我为什么会这样？感谢您不抨击我，因为我是新手。
【问题讨论】：
可能是您的 FOLDER_PATH 相关问题。 System.out.println("解析：" + 路径);这是什么输出？这很可能是 null 代码中的哪一行是第 152 行？ 哦，等等，谢谢，我会检查的。谢谢 您是否设置了写入外部存储的权限？ 【参考方案1】：也许你需要在新设备上创建文件夹
private static final String FOLDER_PATH = Environment.getExternalStorageDirectory() + "/Gps/";
文件目录 = 新文件 (FOLDER_PATH);
private class LoadGpsTask extends AsyncTask<String, Void, List<Gps>>
@Override
protected List<Gps> doInBackground(String... args)
//create folder if not exist
boolean success = true;
if (!dir.exists())
success = dir.mkdir();
if (!success)
// Do something else on failure
// CALL XMLPULLPARSER & RETURN A LIST
String files[] = dir.list(xmlFilter);
【讨论】：
【参考方案2】：在不同的设备和 Android 版本上存在许多问题，无法找到外部存储的真实路径（如果可用）看起来您遇到了其中一个问题，请查看此question，希望它能帮助您找到解决方法完成你的任务。
【讨论】：
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