Android : Reading File

Question

I am trying to get last 10 rows from file but not able to fetch.

i have two activities: in the first, i want to write text from an EditText to a file. in the second activity i try to read the stored data and write it to a textView

public class Date_Location extends Activity {

ImageView imageView;
EditText editTextDate, editTextLocation, editTextEdit;

private static final String TAG = Date_Location.class.getName();
private static final String FILENAME = "myFile.txt";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    this.requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.date_location);

    editTextDate = (EditText) findViewById(R.id.editText1);
    editTextLocation = (EditText) findViewById(R.id.editText2);
    editTextEdit = (EditText) findViewById(R.id.editText3);
    imageView = (ImageView) findViewById(R.id.next);
}

public void goNext(View view) {
    String Date = editTextDate.getText().toString();
    String Location = editTextLocation.getText().toString();
    String Comment = editTextEdit.getText().toString();

    writeToFile(Date);
    writeToFile(Location);
    writeToFile(Comment);

    Intent intent = new Intent(this, Detail_Data.class);
    startActivity(intent);
    Date_Location.this.finish();
}

private void writeToFile(String data) {
    String newline = "\r\n";
    try {

        OutputStreamWriter oswName = new OutputStreamWriter(openFileOutput(
                FILENAME, Context.MODE_APPEND));
        oswName.write(newline);
        oswName.write(data);
        oswName.close();
    } catch (IOException e) {
        Log.e(TAG, "File write failed: " + e.toString());
    }
}
}

And my second Activity is below

public class Detail_Data extends Activity {

TextView textView1;
ImageView imageView;
private static final String FILENAME = "myFile.txt";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.detail_data);

    textView1 = (TextView) findViewById(R.id.textView1);
    imageView = (ImageView) findViewById(R.id.imageView2);

    String date = readFromFile();
    textView1.setText(date);

}

private String readFromFile() {
    String ret = "";

    try {
        InputStream inputStream = openFileInput(FILENAME);
        ArrayList<String> bandWidth = new ArrayList<String>();

        if (inputStream != null) {
            InputStreamReader inputStreamReader = new InputStreamReader(
                    inputStream);
            BufferedReader bufferedReader = new BufferedReader(
                    inputStreamReader);
            String receiveString = "";
            StringBuilder stringBuilder = new StringBuilder();

            while ((receiveString = bufferedReader.readLine()) != null) {
                 stringBuilder.append(receiveString+'\n');
                 bandWidth.add(receiveString);
                 if (bandWidth.size() == 10)
                  bandWidth.remove(0);
                }
            ret = stringBuilder.toString();
            inputStream.close();
        }
    } catch (FileNotFoundException e) {
        Log.i("File not found", e.toString());
    } catch (IOException e) {
        Log.i("Can not read file:", e.toString());
    }
    return ret;
}

public void goNext(View view) {
    imageView.setColorFilter(0xFFFF3D60, PorterDuff.Mode.MULTIPLY);

    Intent intent = new Intent(this, Agreement.class);
    startActivity(intent);
    Detail_Data.this.finish();
}
}

please if any one have any idea then help me. I have tried with other solution too but then also i am not getting last 10 records. Instead of last 10 data i am getting all the records which is written in file.

gokaka · Answer 1 · 2013-10-17T11:46:40.660

Firstly, If you are writing file on SDcard, be sure that you have added the uses-permission tag in AndroidManifest.xml

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

Secondly, don't forget flush()

oswName.write(data);
oswName.flush();
oswName.close();

Then, there is something wrong with your readFromFile() method, remove this line from while loop

stringBuilder.append(receiveString+'\n');

and add this right after the while loop

for(String str : bandWidth)
    stringBuilder.append(str + "\n");

readFromFile() should be like following

private String readFromFile() {
    String ret = "";

    try {
        InputStream inputStream = openFileInput(FILENAME);
        ArrayList<String> bandWidth = new ArrayList<String>();

        if (inputStream != null) {
            InputStreamReader inputStreamReader = new InputStreamReader(
                    inputStream);
            BufferedReader bufferedReader = new BufferedReader(
                    inputStreamReader);
            String receiveString = "";
            StringBuilder stringBuilder = new StringBuilder();

            while ((receiveString = bufferedReader.readLine()) != null) {
                 bandWidth.add(receiveString);
                 if (bandWidth.size() == 10)
                  bandWidth.remove(0);
                }

            for(String str : bandWidth)
                stringBuilder.append(str + "\n");

            ret = stringBuilder.toString();
            inputStream.close();
        }
    } catch (FileNotFoundException e) {
        Log.i("File not found", e.toString());
    } catch (IOException e) {
        Log.i("Can not read file:", e.toString());
    }
    return ret;
}

Hey Ed_W your given solution is working for me but the problem is, instead of Last 10 records it is showing only last 3 records. Any idea why?? — InnocentKiller, Oct 21 '13 at 05:48

Didac Perez Parera · Answer 2 · 2013-10-17T11:03:05.637

0

After opening the input/output stream, use that methods:

import java.io.FileInputStream;
import java.io.FileOutputStream;

public class Files {

    public static String readStringFile(FileInputStream fis) throws java.io.IOException {
        StringBuffer fileContent = new StringBuffer("");

        byte[] buffer = new byte[1024];

        while (fis.read(buffer) != -1) {
            fileContent.append(new String(buffer));
        }

        return fileContent.toString();
    }

    public static void writeStringFile(FileOutputStream fos, String text) throws java.io.IOException {
        fos.write(text.getBytes());
    }
}

First, create the FileInputStream or FileOutputStream with your desired file name and then call the methods above. Please notice that the methods only work for reading and writing strings.

edited Oct 17 '13 at 11:03

answered Oct 17 '13 at 10:56

Didac Perez Parera

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Hey Didac Thanks for your quick reply, but i didn't get you. where should i use this code. – InnocentKiller Oct 17 '13 at 11:00
:) you are welcome. You may put that code in a class, ie. Files.java, so you can use that two methods whenever you want. – Didac Perez Parera Oct 17 '13 at 11:02
Ok After creating Files.java class how do i call this both method, i know i have to call one method in writing file class and one in reading file class but where and when?? – InnocentKiller Oct 17 '13 at 11:26
For reading, as an example, create a FileInputStream and then pass it to readStringFile. – Didac Perez Parera Oct 17 '13 at 11:33

Maxim Shoustin · Answer 3 · 2013-10-17T11:25:45.347

You store each line to list and remove 0 position only if list size = 10

So as 1st step store all file in list:

Instead

while ((receiveString = bufferedReader.readLine()) != null) {
             stringBuilder.append(receiveString+'\n');
             bandWidth.add(receiveString);
             if (bandWidth.size() == 10)
              bandWidth.remove(0);
            }

Write

while ((receiveString = bufferedReader.readLine()) != null) {
             stringBuilder.append(receiveString+'\n');
             bandWidth.add(receiveString);                
            }

After copy last 10 lines to new list.

For example if you have :

List<String> bandWidth = new ArrayList<String>(Arrays.asList("a1", "a2", "a3","a4", "a5", "a6","a7", "a8", "a9","a10", "a11", "a12"));

Than with subList:

List<String> bandWidth10rows= bandWidth.subList(bandWidth.size()-10, bandWidth.size());

It will copy last 10 list items to new list.

Totally it should be something like:

while ((receiveString = bufferedReader.readLine()) != null) {
             stringBuilder.append(receiveString+'\n');
             bandWidth.add(receiveString);                
            }
List<String> bandWidthLastTenRows= bandWidth.subList(bandWidth.size()-10, bandWidth.size());

Hello Maxim, I have tried your solution but it's not working correctly. Can you please tell me exactly how and what piece of code i need to replace and where?? — InnocentKiller, Oct 17 '13 at 11:22

Android : Reading File

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