How to create a file in Android?

I used the following code to create a temporary file for writing bytes. And its working fine.

File file = new File(Environment.getExternalStorageDirectory() + "/" + File.separator + "test.txt"); file.createNewFile(); byte[] data1={1,1,0,0}; //write the bytes in file if(file.exists()) { OutputStream fo = new FileOutputStream(file); fo.write(data1); fo.close(); System.out.println("file created: "+file); } //deleting the file file.delete(); System.out.println("file deleted"); 

From here: http://www.anddev.org/working_with_files-t115.html

//Writing a file... try { // catches IOException below final String TESTSTRING = new String("Hello Android"); /* We have to use the openFileOutput()-method * the ActivityContext provides, to * protect your file from others and * This is done for security-reasons. * We chose MODE_WORLD_READABLE, because * we have nothing to hide in our file */ FileOutputStream fOut = openFileOutput("samplefile.txt", MODE_PRIVATE); OutputStreamWriter osw = new OutputStreamWriter(fOut); // Write the string to the file osw.write(TESTSTRING); /* ensure that everything is * really written out and close */ osw.flush(); osw.close(); //Reading the file back... /* We have to use the openFileInput()-method * the ActivityContext provides. * Again for security reasons with * openFileInput(...) */ FileInputStream fIn = openFileInput("samplefile.txt"); InputStreamReader isr = new InputStreamReader(fIn); /* Prepare a char-Array that will * hold the chars we read back in. */ char[] inputBuffer = new char[TESTSTRING.length()]; // Fill the Buffer with data from the file isr.read(inputBuffer); // Transform the chars to a String String readString = new String(inputBuffer); // Check if we read back the same chars that we had written out boolean isTheSame = TESTSTRING.equals(readString); Log.i("File Reading stuff", "success = " + isTheSame); } catch (IOException ioe) {ioe.printStackTrace();} 

I decided to write a class from this thread that may be helpful to others. Note that this is currently intended to write in the "files" directory only (e.g. does not write to "sdcard" paths).

import java.io.BufferedReader; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStreamReader; import java.io.OutputStreamWriter; import android.content.Context; public class AndroidFileFunctions { public static String getFileValue(String fileName, Context context) { try { StringBuffer outStringBuf = new StringBuffer(); String inputLine = ""; /* * We have to use the openFileInput()-method the ActivityContext * provides. Again for security reasons with openFileInput(...) */ FileInputStream fIn = context.openFileInput(fileName); InputStreamReader isr = new InputStreamReader(fIn); BufferedReader inBuff = new BufferedReader(isr); while ((inputLine = inBuff.readLine()) != null) { outStringBuf.append(inputLine); outStringBuf.append("\n"); } inBuff.close(); return outStringBuf.toString(); } catch (IOException e) { return null; } } public static boolean appendFileValue(String fileName, String value, Context context) { return writeToFile(fileName, value, context, Context.MODE_APPEND); } public static boolean setFileValue(String fileName, String value, Context context) { return writeToFile(fileName, value, context, Context.MODE_WORLD_READABLE); } public static boolean writeToFile(String fileName, String value, Context context, int writeOrAppendMode) { // just make sure it's one of the modes we support if (writeOrAppendMode != Context.MODE_WORLD_READABLE && writeOrAppendMode != Context.MODE_WORLD_WRITEABLE && writeOrAppendMode != Context.MODE_APPEND) { return false; } try { /* * We have to use the openFileOutput()-method the ActivityContext * provides, to protect your file from others and This is done for * security-reasons. We chose MODE_WORLD_READABLE, because we have * nothing to hide in our file */ FileOutputStream fOut = context.openFileOutput(fileName, writeOrAppendMode); OutputStreamWriter osw = new OutputStreamWriter(fOut); // Write the string to the file osw.write(value); // save and close osw.flush(); osw.close(); } catch (IOException e) { return false; } return true; } public static void deleteFile(String fileName, Context context) { context.deleteFile(fileName); } } 

Write to a file test.txt:

String filepath ="/mnt/sdcard/test.txt"; FileOutputStream fos = null; try { fos = new FileOutputStream(filepath); byte[] buffer = "This will be writtent in test.txt".getBytes(); fos.write(buffer, 0, buffer.length); fos.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); }finally{ if(fos != null) fos.close(); } 

Read from file test.txt:

String filepath ="/mnt/sdcard/test.txt"; FileInputStream fis = null; try { fis = new FileInputStream(filepath); int length = (int) new File(filepath).length(); byte[] buffer = new byte[length]; fis.read(buffer, 0, length); fis.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); }finally{ if(fis != null) fis.close(); } 

Note: don't forget to add these two permission in AndroidManifest.xml

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />