Writing-to and Reading-from a file in Android

I’m  lazy to redo work..So, presenting working code right infront of you :-).I think comments are sufficient to explain how the things are working....

package org.sample.example.download;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStreamReader;

import android.content.Context;

public class ReadWriteFileManager {

     

     

       public String readFromFile(Context context,String sourceFileName)

       {

             /*

              * Reading will be file type specific..

              * Here I'm considering text file alone..

              *

              */

            FileInputStream fis=null;

            InputStreamReader isr = null;

           

            char[] inputBuffer=null;

            String file_content = null;

           

            try

            {   

                  //As this requires full path of the file...

                  //i.e data/data/package_name/files/your_file_name

                  File sourceFile=

newFile(context.getFilesDir().getPath()

+File.separator+sourceFileName);

                  if(sourceFile.exists())

                  {                      

                        //Probably you will get an exception if its

//a huge content file..

                        //I suggest you to handle content here

//itself, instead of

                        //returning it as return value..

                        inputBuffer=new char[(int) sourceFile.length()];

                 

                        fis=context.openFileInput(sourceFileName);                 

                       

                        isr = new InputStreamReader(fis);                    

                        isr.read(inputBuffer);

                       

                        file_content = new String(inputBuffer);                    

                                                           

                        try

                        {    

                              isr.close();

                              fis.close();

                        }

                        catch (IOException e)

                        {    

                              e.printStackTrace();

                        }

                  }

                 

            }

            catch (Exception e)

            {    

                  e.printStackTrace();

                  file_content=null;

            }

                 

            return file_content;

          }

         

         

public boolean writeToFile(Context context,

byte [] contentToWrite,String destinationFileName)

      {

            FileOutputStream fos=null;

            boolean retValue=false;

            try

            {

                  //Note that your file will be created and stored

                  //under the path: data/data/your_app_package_name/files/

fos=context.openFileOutput(destinationFileName, Context.MODE_PRIVATE);

                 

                  //Note that we are not buffering of contents to write..

                  //So, this will work best for files with less content....

                  fos.write(contentToWrite);

                  //Successfully completed writing..

                  retValue=true;   

                  try

                  {

                        fos.flush();

                        fos.close();

                  }

                  catch (IOException e)

                  {                      

                        e.printStackTrace();

                  }

            }

            catch (Exception e)

            {    

                  //You can catch exceptions specifically for low mem,

                  //file cant be created, and so on..

                  e.printStackTrace();

                  //Failed to write..

                  retValue=false;

            }

                 

            return retValue;       

      }

}

Sample code snippets of how you may use above class is as shown below:

final String TEMP_FILE_NAME="temp.txt";

String contentToWrite="THIS IS THE CONTENT TO WRITE!";

Log.d("DEBUG","Instantiating ReadWriteManager..");

ReadWriteFileManager readWriteFileManager=new ReadWriteFileManager();   

      Log.d("DEBUG","Writing to file..."); 

readWriteFileManager.writeToFile(this,contentToWrite.getBytes(),

TEMP_FILE_NAME );

      Log.d("DEBUG","Reading from file..");

String contentRead= readWriteFileManager.readFromFile(this, TEMP_FILE_NAME);

      Log.d("DEBUG","Content read: "+contentRead);

Once done, you may find your file under DDMS>File Explorer>data/data/package_name/files/

Happy coding :-)

.