I am trying to download a file using the Box android SDK. The problem seems to be with the destinationFile parameter. The box.com call is checking whether the destinationFile exists - but why? I get java.io.FileNotFoundException.
destinationFile = new File(getFilesDir(), "myfile.crs");
// destinationFile = new File(getFilesDir(),"/");
try {
BoxDownload fileDownload = mFileApi.getDownloadRequest(destinationFile, fileID)
// Optional: Set a listener to track download progress.
.setProgressListener(new ProgressListener() {
#Override
public void onProgressChanged(long numBytes, long totalBytes) {
// Update a progress bar, etc.
}
})
.send();
} catch (BoxException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
To do All the checks
Log.i(getClass().getName(),"Does File exists:"+(destinationFile.exists()?"Yes":"No"));
Log.i(getClass().getName(),"Is it A file:"+(destinationFile.isFile()?"Yes":"No"));
Log.i(getClass().getName(),"Is it Writable:"+(destinationFile.canWrite()?"Yes":"No"));
Log.i(getClass().getName(),"Is it A Readable:"+(destinationFile.canRead()?"Yes":"No"));
Log.i(getClass().getName(),"Path:"+destinationFile.getAbsolutePath());
you are most likely to found file does not exists then do this before using it.
if(!destinationFile.exists()){
try {
destinationFile.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
The answer was to create a new File. Then call .createNewFile() on the File instance. Then call all of the code I posted except to put run it in the background. That's why I was asking here - I was wondering if I was doing something incorrect for Android and I was. Box networking operations need to be done on a thread.
Too bad they never show this for downloading a file. Too bad there's not one example of downloading a file with the Android DSK on the web.
Related
after I run any application on my phone, using free version of AIDE -IDE Android, everytime I view LogCat, I get the same message : " run the app to see the log output ".!
Here is the following screenshot :(https://i.stack.imgur.com/uLORU.png)
Is LogCat free on AIDE-IDE Google play app ?
Thank you for your attention.
It's free as far as i know, but you need root access in order for log to work.
Besides: it doesn't work from time to time with root either.
Another option: use following function to log to local file:
public void appendLog(String text)
// https://stackoverflow.com/a/6209739
{
File logFile = new File("sdcard/log.file");
if (!logFile.exists())
{
try
{
logFile.createNewFile();
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
try
{
//BufferedWriter for performance, true to set append to file flag
BufferedWriter buf = new BufferedWriter(new FileWriter(logFile, true));
buf.append(text);
buf.newLine();
buf.flush();
buf.close();
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
Use it like this:
try{
// your code goes here
}catch (Exception e){
appendLog(e.getMessage());
}
You need to add permission for writing_external_storage in Manifest.
There is no problem with your code. However the problem is with AIDE version your using. Am using the Pro and Logcat is working fine for me
I found this way, as shown below, using Log.getStackTraceString(Exception e), to solve my LogCat View trouble on AIDE-IDE Android. The only remaining question is why there is no display of Log.e (TAG,"Exception ",e) ?
Thank you for your attention.
Code of MainActivity (https://i.stack.imgur.com/Dqfc5.png)
Hi Iam having serious issues try to persist some serializable objects to a file on the local android file system. Iam getting a Bad file descriptor error and I think it is to do with my methods for creating the file. the file and checking if the file exists. i create a private file object in the class. Then, on write or read. I check file existance with the following code.
#Override
public boolean fileExists() {
File file = context.getFileStreamPath(filename);
return file.exists();
}
this doesnt instantiate my file object called "objectfile"!! but does check the "filename" exists.
to create the file I call this method if "filename" doesnt exist.
public void createFile()
{
objectfile = new File(context.getFilesDir(), filename);
objectfile.setReadable(true);
objectfile.setWritable(true);
}
Iam not sure if this will give me back my previously created file which would be ideally what I want to do. Is there a way i can just get the old file or create a new one and pass it to "objectfile" variable in the constructor??
Iam also wondering what the best way to do this is??
Or should i just use the mysqlite db? using object file persistance doesn't seem to be working out for me right now and iam working to a deadline. Also this method is mention in the gooogle docs so I thought it would be legit was to do it.
http://developer.android.com/training/basics/data-storage/files.html
here is my method for reading the serializable objects
public synchronized ArrayList<RoomItem> readObjects() {
final ArrayList<RoomItem> readlist = new ArrayList<>();
if(!fileExists())
return readlist;
if(objectfile == null)
createFile();
try {
finputstream = new FileInputStream(objectfile);
instream = new ObjectInputStream(finputstream);
readwritethread = new Thread(new Runnable() {
#Override
public void run() {
try {
final ArrayList<RoomItem> readitems = (ArrayList<RoomItem>) instream.readObject();
instream.close();
finputstream.close();
handler.post(new Runnable() {
#Override
public void run() {
listener.updateList(readitems);
}
});
} catch(IOException e)
{
e.printStackTrace();
}
catch(ClassNotFoundException e)
{
e.printStackTrace();
Log.d("read failed", "file read failed");
}
}
});
}
catch(Exception e)
{
e.printStackTrace();
}
timeOutReadWrite(readwritethread);
readwritethread.start();
try {
readwritethread.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
Log.d("read from file", "file read");
return readlist;
if anyone could suggest any improvements id really appreciate it. I use a handler to pass back to my activity and implement a listener interface on my activity thats call the activity when all the obj are read. Thanks again!
1#: Yes, it will return the original file you created.
2#: Depends on the thing you want to store, seems File is more flex from description
hope helpful.
We have used
FileOutputStream fos = context.openFileOutput("file.ser", Context.MODE_PRIVATE);
to write our serialized files.This will carete files in /data/data/app.package.name/files/. In fact, this path is returned by getFilesDir().
And while deserializing, use
//make sure you pass the same file that was passed to openFileOutput()..
FileInputStream fis = context.openFileInput("file.ser");
Also, to avoid confusing between file names you can use name of class that is being serialized.
Ex:
public static <T> void serialize(final Context context, final T objectToSerialize) {
....
....
Strin fileName = objectToSerialize.getClass().getSimpleName();
...
}
Do this and keep the method in util so it can be used for any type of objects (T type) to serialize.
I'm trying to build a plugin-System, where DexClassLoader is fetching code from other installed apks containing fragments(my plugins), and showing them in my host. This is working quite nice.
I also like to make the plugins hotswappable, this means I can change the code from a plugin, install it new and the host will notice and will load the new code. This also works, if I'm changing the code for the first time. (Although I thought it shouldn't, it seems I've got a wrong understanding of this code:
try {
requiredClass = Class.forName(fullName);
} catch(ClassNotFoundException e) {
isLoaded = false;
}
)
If i'm trying it a second time with the same plugin, the host shuts down at requiredClass = classLoader.loadClass(fullName); with something like
libc Fatal signal 7 (SIGBUS) at 0x596ed4d6 (code=2), thread 28814
(ctivityapp.host)
Does anybody has a deeper insight in the functionality of DexClassLoader and may tell me, what is happening here? I'm quite stuck at this.
Heres the full code of the method loading the foreign code:
/**
* takes the name of a package as String, and tries to load the code from the corresponding akp using DexclassLaoder.
* Checking if a package is a valid plugin must be done before calling this.
* The Plugin must contain a public class UI that extends Fragment and implements plugin as a starting point for loading
* #param packageName The full name of the package, as String
* #return the plugins object if loaded, null otherwise
*/
private Plugin attachPluginToHost(String packageName) {
try {
Class<?> requiredClass = null;
final ApplicationInfo info = context.getPackageManager().getApplicationInfo(packageName,0);
final String apkPath = info.sourceDir;
final File dexTemp = context.getDir("temp_folder", 0);
final String fullName = packageName + ".UI";
boolean isLoaded = true;
// Check if class loaded
try {
requiredClass = Class.forName(fullName);
} catch(ClassNotFoundException e) {
isLoaded = false;
}
if (!isLoaded) {
final DexClassLoader classLoader = new DexClassLoader(apkPath, dexTemp.getAbsolutePath(), null, context.getApplicationContext().getClassLoader());
requiredClass = classLoader.loadClass(fullName);
}
if (null != requiredClass) {
// Try to cast to required interface to ensure that it's can be cast
final Plugin plugin = Plugin.class.cast(requiredClass.newInstance());
installedPlugins.put(plugin.getName(), plugin);
return plugin;
}
} catch (PackageManager.NameNotFoundException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
return null;
}
Many thanks in advance!
Not that it really matters (As nobody is actually viewing this), or that I even understand what's going on, but deleting the corresponding file of the plugin in dexTemp.getAbsolutePath() before reloading it solves the problem.
PS: Tumbleweed-Badge, YAY!
I am currently writing an android app that logs the accelerometer. (its a test app at the moment so i can prototype an algorithm.
To write out a list of SensorEventStore's (which is just a way of storing the data from a SensorEvent) to the SD card from a 30 minute recording, locks up the GUI for about 20 - 30 seconds while writing the file.
I am using the following code to write out the file to the SD card.
#Override
public void onMessage(Messages message, Object param[]) {
if(message == IDigest.Messages.SaveData) {
File folder = (File) param[0];
File accFileAll = new File(folder, startTime + "_all.acc");
FileWriter accFileWriterAll;
try {
accFileWriterAll = new FileWriter(accFileAll);
} catch (IOException e) {
accFileWriterAll = null;
}
for(Iterator<SensorEventStore> i=eventList.iterator(); i.hasNext();) {
SensorEventStore e = i.next();
if(accFileWriterAll != null) {
try {
accFileWriterAll.write(
String.format(
"%d,%d,%f,%f,%f\r\n",
e.timestamp,
e.accuracy,
e.values[0],
e.values[1],
e.values[2]
)
);
accFileWriterAll.flush();
} catch (IOException ex) {
}
}
}
new SingleMediaScanner(RunBuddyApplication.Context, accFileAll);
}
}
Can anyone give me any pointers to make this not lock up the UI, or not have to take the amount of time it currently takes to write out the file.
Firstly you should try to do this in the background. The AsyncTask is fairly well suited for the task.
Other than that, you should remove the flush() statement, and probperly close() your file writer. The flush causes the data to be written to disk in rather small portions, which is really slow. If you leave the filewriter to its own flushing, it will determine a buffer size on its own. When you properly close the FileWriter, the remaining data should be written to disk as well.
Also, you could take a look at "Try with resources" for your filewriter, but that is optional.
I'm using usb-serial-for-android library and I am getting some strange results. After 2.5 hours of continuous communicating with the serial port and reading and writing successfully, I get this exception:
exception in UsbManager.openDevice
android.os.TransactionTooLargeException
at android.os.BinderProxy.transact(Native Method)
at android.hardware.usb.IUsbManager$Stub$Proxy.openDevice(IUsbManager.java:339)
at android.hardware.usb.UsbManager.openDevice(UsbManager.java:255)
at com.hoho.android.usbserial.driver.UsbSerialProber$1.probe(UsbSerialProber.java:63)
at com.hoho.android.usbserial.driver.UsbSerialProber.probeSingleDevice(UsbSerialProber.java:174)
But when i force close my app and then restart it, everything is fine and my app can communicate with the port again.
It maybe useful to mention that before the exception , I get this exception:
java.io.FileNotFoundException: /sdcard/log.txt: open failed: EMFILE (Too many open files)
at libcore.io.IoBridge.open(IoBridge.java:406)
at java.io.FileOutputStream.<init>(FileOutputStream.java:88)
at java.io.FileWriter.<init>(FileWriter.java:58)
at org.example.myapp.util.L.log(L.java:32)
I use class L for logging purposes:
public class L {
public synchronized void log(String message){
File logFile = new File("sdcard/log.txt");
if (!logFile.exists())
{
try
{
logFile.createNewFile();
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
try
{
//BufferedWriter for performance, true to set append to file flag
BufferedWriter buf = new BufferedWriter(new FileWriter(logFile, true));
buf.append(new Date(DateProvider.getInstance().getCurrentDateAsMillisecs()).toString()+": "+message);
buf.newLine();
buf.close();
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
It seems that some kind of buffer or cache is getting filled and prevents communicating with the device.
How can I get rid of the exception?
Update:
Writing to log file never fails even though I'm getting the exception. It only affects communicating with usb device.
You are opening too many files.
Problems I have found:
- You never close logFile
- You open the file in the log function, a static File would be better and could be initialized in a log_init(); function.
Or, make logFile an object variable and initialize it in the constructor.
I think solving these will solve your problem.
Can you not use getFilesDir() to pass the directory path while creating file
public class L {
public static File logFile = new File("sdcard/log.txt");
public synchronized void log(String message){
....
Everytime you call new File you request a file resource from the system. As you keep doing it the system will complain that you opened too many files. To avoid this, request the file only once.