I want to create/write new files on the device.
I am able to create file on sd card of the android device.
But in case if device is not having sd card then where should i create file which can be accessible from the ddms.
I tried to create it in /data/data/com.abc.app/files/ directory, But i don't have permissions to access this directory from the ddms to save the file on pc.
Which is the best location create new file on the device which can be access from ddms and application.
Try use cache dir local and external.
Here is a part of my code
File dir = context.getExternalCacheDir() != null ?
context.getExternalCacheDir() : context.getCacheDir();
File file = new File(dir, ".cachefile");//hidden
if (file.exists())
file.delete();
FileOutputStream out = new FileOutputStream(file);
//..
out.flush();
out.close();
Don't forget to have permissions read/write;
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
you have the permission to write/read in/from that folder through your applicatin. You have to use the pair openFileInput/openFileOutput
here the doc per openFileInput/openFileOutput
Related
I want to write to the physical SD card in my Android phone.
This is my code:
File sdCard = Environment.getExternalStorageDirectory();
String state = Environment.getExternalStorageState(); //shows mounted
boolean removable = Environment.isExternalStorageRemovable(); //shows false
I know that the external in getExternalStorageDirectory() not necessarily means the SD card. When I write a file to sdCard object it ends up in the internal (means build in) storage and not on the sdCard.
On my mobile I have multiple apps which write data to the sdCard, e.g. file explorer. How do they do it? I want to force to write to sdCard regardless what the manufacturer thinks is internal/external.
File sdCard = Environment.getExternalStorageDirectory();
File dir = new File (sdCard.getAbsolutePath() + "/dir1/dir2");
dir.mkdirs();
File file = new File(dir, "filename");
FileOutputStream f = new FileOutputStream(file);
...
Caution: Files on external storage are not always accessible, because users can mount the external storage to a computer for use as a storage device. So if you need to store files that are critical to your app's functionality, you should instead store them on internal storage.
Request external storage permissions
To write to the public external storage, you must request the WRITE_EXTERNAL_STORAGE permission in your manifest file:
<manifest ...>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
...
</manifest>
Note: If your app uses the WRITE_EXTERNAL_STORAGE permission, then it implicitly has permission to read the external storage as well.
If your app only needs to read the external storage (but not write to it), then you need to declare the READ_EXTERNAL_STORAGE permission:
<manifest ...>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
...
</manifest>
https://developer.android.com/training/data-storage/files.html
Now, let's say that for example you want to record a text file in your SD ...
// get the path to sdcard
File sdcard = Environment.getExternalStorageDirectory();
// to this path add a new directory path
File dir = new File(sdcard.getAbsolutePath() + "/your-dir-name/");
// create this directory if not already created
dir.mkdir();
// create the file in which we will write the contents
File file = new File(dir, "My-File-Name.txt");
FileOutputStream os = outStream = new FileOutputStream(file);
String data = "This is the content of my file";
os.write(data.getBytes());
os.close();
I have created an android app that needs to create a folder and write text files on my external SD card(extSdCard). I am using the Galaxy S4 device and have written the following codes for that. I already know the path of /mnt/.. file and have created a string for it. The android manifest.xml file uses the permission.i have checked the codes in "adb logcat" in Cmd prompt and it does not give any error but doesn't create any folder. The device has also been checked unconnected with the PC. Would appreciate if you help me. Here is the code.
String externalFilePath="/mnt/extSdCard/tmp";
Log.d(TAG, "externalFilePath is: "+externalFilePath);
File myfile = new File(externalFilePath, "Hello");
First of all make sure that you have this line inside your manifest,xml, somewhere outside application tag.
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
Then you can write a File doing this :
File sdcard = Environment.getExternalStorageDirectory();
File dir = new File(sdcard.getAbsolutePath() + "/tmp/");
// creates if doesn't exists
dir.mkdir();
// create a File
File file = new File(dir, "Example.txt");
FileOutputStream os = outStream = new FileOutputStream(file);
//this is the text that will be inside of the Example.txt
String data = "Hello world";
os.write(data.getBytes());
os.close();
Hope it helps :)
try this code to generate files under your application package
File path = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
// Replace DIRECTORY_PICTURES with your needs
File file = new File(path, "Hello");
Also make sure you have added the permissions
I am trying to create a file and store it in SD Card to be used as an input for some processing for an apps.
After searching for a while, I got this code which can create a file in SD card.But after running this,I couldn't see any file created in my SD card. Can anyone please help me what I am missing here.
BufferedWriter out = new BufferedWriter(new FileWriter(FileDescriptor.err));
try {
File root = Environment.getExternalStorageDirectory();
if (root.canWrite()) {
File perffile = new File(root, "samplefile.txt");
FileWriter perfwriter = new FileWriter(perffile, true);
out = new BufferedWriter(perfwriter);
}
} catch (IOException e) {
Log.e(TAG, "-Could not write file " + e.getMessage());
return;
}
If you want to add a file or folder or move application into your SD Card just do the following:
steps:
1) Open your Android application's source code file with a text or programming editor.
2) Browse to the location in the source code where you wish to call the function that writes a file to the device's external storage.
3) Insert this single line of code to check for the SD card:
File sdCard = Environment.getExternalStorageDirectory();
4) Insert these lines of code to set the directory and file name:
File dir = new File (sdcard.getAbsolutePath() + "/folder1/folder2");
dir.mkdirs();
File file = new File(dir, "example_file");
// The mkdirs funtion will create the directory folder for you, use it only you want to create a new one.
5) Replace "/folder1/folder2" in the above code with the actual path where you intend to save the file. This should be a location in which you normally save your application files. Also, change the "example_file" value to the actual file name you wish to use.
6) Insert the following line of code to output the file to the SD card:
FileOutputStream f = new FileOutputStream(file);
Finally step 7:
Save the file, then compile it and test the application using the Android emulator software or the device.
This will works!!! ;-)
Im trying to save data to sdCard first i tried to saave it privately within app directory on externalStorage using getExternalFilesDir but gives me nullPointerException so i tried the other way given below it worked but when i want to store files into a custom directory that i want to named myself it give me error:
FileOutputStream os;
dirName = "/mydirectory/";
try {
if (android.os.Environment.getExternalStorageState().equals(
android.os.Environment.MEDIA_MOUNTED)){
File sdCard = Environment.getExternalStorageDirectory();
File dir = new File (sdCard.getAbsolutePath() + dirName);
dir.mkdirs();
//File file = new File(this.getExternalFilesDir(null), this.dirName+fileName); //this function give null pointer exception so im using other one
File file = new File(dir, dirName+fileName);
os = new FileOutputStream(file);
}else{
os = context.openFileOutput(fileName, MODE_PRIVATE);
}
resizedBitmap.compress(CompressFormat.PNG, 100, os);
os.flush();
os.close();
}catch(Exception e){
}
ErrorLog:
java.io.FileNotFoundException: /mnt/sdcard/mvc/mvc/myfile2.png (No such file or directory)
Your directory "/mnt/sdcard/mvc/mvc" may not exist. What about changing your path to store the image in the Environment.getExternalStorageDirectory() path and then working from there?
Also, as Robert pointed out, make sure you have write permission to external storage in your manifest.
Edit - to create directories:
String root = Environment.getExternalStorageDirectory().toString();
new File(root + "/mvc/mvc").mkdirs();
Then you can save a file to root + "/mvc/mvc/foo.png".
Have you requested permission to write onto SD card? Add the following string to you app manifest:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
You should check if you have added the required permission android.permission-group.STORAGE to your app. Without that permission you won't be able to access anything on the SD-Card.
BTW: On the Android system I know the SD-card is mounted on /sdcard not /mnt/sdcard
I found this book to be very helpful: "Pro Android Media: Developing Graphics, Music, Video, and Rich Media Apps for Smartphones and Tablets". I noticed a part that allows saving images and stuff to the SD card.
I m using Android 1.5 my data directory doesn't have the read/write permissions
System.out.println("DAta can write??--->"+Environment.getDataDirectory().canWrite());
System.out.println("DAta can read??--->"+Environment.getDataDirectory().canRead());
So please suggest me how to provide permissions for the data directory.
What I'm trying to do is to create a file and add some content to it in the Data storage of the emulator like as below
private void writeToSDCard() {
try {
File lroot = Environment.getDataDirectory();
if (lroot.canWrite()){
File lfile = new File(lroot, "samplefile.txt");
FileWriter lfilewriter = new FileWriter(lfile);
BufferedWriter lout = new BufferedWriter(lfilewriter);
lout.write("XXXXXXXXXXXXXXXXXX");
lout.close();
}
} catch (IOException e) {
Log.e(m_cTAG, "Could not write file " + e.getMessage());
}
}
You shouldn't be looking at the Data Directory. This is a system directory in the phone's storage - usually /data - and your application will never have permission to write to it.
The directory your application should write files to is returned by the Context.getFilesDir() method. It will be something like /data/data/com.yourdomain.YourApp/files.
If you want to write to a file in the phone's storage use the Context.openFileOutput() method.
If you want the path to the SDCard then use Environment.getExternalStorageDirectory() method. To write to the SDCard you'll need to give your application the appropriate permissions by adding the following to your Manifest:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
If you're going to write to the SDCard you'll also need to check its state with the getExternalStorageState() method.
If you're storing small files to do with your application then these can go into the phone's storage and not the SD Card, so use the Context.openFileOutput() and Context.openFileInput() methods.
So in your code consider something like:
OutputStream os = openFileOutput("samplefile.txt", MODE_PRIVATE);
BufferedWriter lout = new BufferedWriter(new OutputStreamWriter(os));
you need to locate your save build location, sometimes its automatically located in the read-only area on your pc