i have problem with file writing. I want to create OnClick method of button that add line to file on sdcard but instead it delete previous line and put all content in place of current one. In result i got only the Text i put at the last click of Button, here is my code:
if (txtFile.createNewFile() || txtFile.isFile()) {
FileOutputStream fOut = null;
try {
fOut = new FileOutputStream(txtFile);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
OutputStreamWriter myOutWriter = new OutputStreamWriter(fOut);
BufferedWriter bwriter = new BufferedWriter(myOutWriter);
EditText desc__ = (EditText)findViewById(R.id.descriptionEditTExt);
try {
bwriter.newLine();
bwriter.write(lat+"|"+lng+"|"+desc__.getText().toString()+"|"+f+"|"+position);
bwriter.close();
myOutWriter.close();
fOut.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} else {
/* handle directory here */
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Please rewrite your FileOutputStream constructor as
FileOutputStream fos = new FileOutputStream(file, true);
here is suggests that your file will be opened in the append mode which will solve your first problem..
secondly if you want to add new line to the file use "\r\n" string
e.g. fos.write("\r\n".getBytes());
Hope this helps..
Related
Honestly, I've searched a lot do this task so I ended up trying various methods but nothing worked until I ended up on this code. It works for me perfectly like it should, so I do not want to change my code.
The help I need is to put this code in a such a way that it begins to read a file, but if it the file doesn't exist then it will create a new file.
Code for saving data:
String data = sharedData.getText().toString();
try {
fos = openFileOutput(FILENAME, MODE_PRIVATE);
fos.write(data.getBytes());
fos.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Code for loading data:
FileInputStream fis = null;
String collected = null;
try {
fis = openFileInput(FILENAME);
byte[] dataArray = new byte [fis.available()];
while (fis.read(dataArray) != -1){
collected = new String(dataArray);
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
try {
fis.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
So If I add the saving data code in to the "FileNotFoundException" catch of the loading data part then could I achieve what I want?
Add
File file = new File(FILENAME);
if(!file.exists())
{
file.createNewFile()
// write code for saving data to the file
}
above
fis = openFileInput(FILENAME);
This will check if there exists a File for the given FILENAME and if it doesn't it will create a new one.
If you're working on Android, why don't you use the API's solution for saving files?
Quoting:
String filename = "myfile";
String string = "Hello world!";
FileOutputStream outputStream;
try {
outputStream = openFileOutput(filename, Context.MODE_PRIVATE);
outputStream.write(string.getBytes());
outputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
You should really read the whole document, they explain pretty well the basic ways of creating or accessing files, you can also check the different ways of storing data.
But regarding your original question:
So If I add the saving data code in to the "FileNotFoundException"
catch of the loading data part then could I achieve what I want?
Yes, you could achieve it.
Try this one:
public static void readData() throws IOException
{
File file = new File(path, filename);
if (!file.isFile() && !file.createNewFile()){
throw new IOException("Error creating new file: " + file.getAbsolutePath());
}
BufferedReader r = new BufferedReader(new FileReader(file));
try {
// ...
// read data
// ...
}finally{
r.close();
}
}
Ref: Java read a file, if it doesn't exist create it
I am just a beginner in learning Android.I want to learn how to write a piece of text to a file in Android.
My code to write, on clicking a button looks like this:
write.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
FileOutputStream fos;
try {
fos = openFileOutput("filename", Context.MODE_PRIVATE);
fos.write(data.getBytes());
fos.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
tv.setText("Values saved");
}
});
When I execute this the FileNotFoundException is thrown in logcat. As far as I know a new file will be created if no file with such name exists.
The logcat message is:
> 05-14 08:37:55.085: W/System.err(281): java.io.FileNotFoundException: /data/data/com.example.myproject11/files/test (No such file or directory)
First we should check, file is exists or not. Better you try:
File fileDir = new File("filepath");
if (!fileDir.exists())
fileDir.mkdirs();
try {
File file = new File(fileDir, "filename");
FileOutputStream outputStream = new FileOutputStream(file);
outputStream.write(data.getBytes());
outputStream.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
tv.setText("Values saved");
I am able to write and then read a text file in the SAME activity, but I am unable to read a text file after writing to it from another Activity.
Ex: Activity A creates and writes to a text file. Activity B reads that text file.
I use this code to write to the text file in Activity A:
FileOutputStream fos = null;
OutputStreamWriter osw = null;
try
{
fos = openFileOutput("user_info.txt", Context.MODE_WORLD_WRITEABLE);
osw = new OutputStreamWriter(fos);
osw.write("text here");
osw.close();
fos.close();
}
catch (FileNotFoundException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
And then I use this code to try and read the same text file created by Activity A, but I get a FileNotFoundException:
try
{
FileInputStream fis = openFileInput("user_info.txt");
InputStreamReader isr = new InputStreamReader(fis);
BufferedReader buff = new BufferedReader(isr);
String line;
while((line = buff.readLine()) != null)
{
Toast.makeText(this, line, Toast.LENGTH_LONG).show();
}
}
catch (FileNotFoundException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
Does anyone know why I am getting the FileNotFoundException?
Is it a path issue?
Don't really know how is built your application, but, the error you get does seem like a path issue, are you sure both Activities are in the same folder ?
If not, you'll need to set either an abolute path (like : "/home/user/text.txt") for the text file or a relative path (like : "../text.txt").
If you're not sure, try to print the current path for the Activity using some command like
new File(".").getAbsolutePath();
And, although I can't say I'm expert with Android, are you sure you need the Context.MODE_WORLD_WRITEABLE for your file ? If no other application than yours is reading or writing from/to it, it should not be necessary, right ?
it is surealy a path issue.
you can write like this
fpath=Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+"yourdirectory";
File custdir=new File(fpath);
if(!custdir.exists())
{
custdir.mkdirs();
}
File savedir=new File(custdir.getAbsolutePath());
File file = new File(savedir, filename);
if(file.exists())
{
file.delete();
}
FileOutputStream fos;
byte[] data = texttosave.getBytes();
try {
fos = new FileOutputStream(file);
fos.write(data);
fos.flush();
fos.close();
Toast.makeText(getBaseContext(), "File Saved", Toast.LENGTH_LONG).show();
finish();
} catch (FileNotFoundException e) {
Toast.makeText(getBaseContext(), "Error File Not Found", Toast.LENGTH_LONG).show();
Log.e("fnf", ""+e.getMessage());
// handle exception
} catch (IOException e) {
// handle exception
Toast.makeText(getBaseContext(), "Error IO Exception", Toast.LENGTH_LONG).show();
}
and you can read like
String locatefile=Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+"yourdirectory"+"/filename";
try {
br=new BufferedReader(new FileReader(locatefile));
while((text=br.readLine())!=null)
{
body.append(text);
body.append("\n");
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
I'm so confused. After reading this thread, I'm trying to write a List to internal storage onPause(), then read the List onResume(). Just for testing purposes, I'm trying to write a simple string as the example showed. I've got this to write with:
String FILENAME = "hello_file";
String string = "hello world!";
FileOutputStream fos = null;
try {
fos = openFileOutput(FILENAME, Context. MODE_WORLD_READABLE);
} catch (FileNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {
fos.write(string.getBytes());
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {
fos.close();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
And I'm trying to read it in onResume() by calling:
try {
resultText01.setText(readFile("hello_file"));
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
resultText01.setText("exception, what went wrong? why doesn't this text say hello world!?");
}
Which of course uses this:
private static String readFile(String path) throws IOException {
FileInputStream stream = new FileInputStream(new File(path));
try {
FileChannel fc = stream.getChannel();
MappedByteBuffer bb = fc.map(FileChannel.MapMode.READ_ONLY, 0, fc.size());
/* Instead of using default, pass in a decoder. */
return Charset.defaultCharset().decode(bb).toString();
}
finally {
stream.close();
}
}
For some reason, resultText01.setText(...) isn't being set to "hello world!", and is instead calling the catch exception. I'm sorry if my lingo isn't correct, I'm new to this. Thanks for any pointers.
Instead of the following in your readFile(...) method...
FileInputStream stream = new FileInputStream(new File(path));
Try...
FileInputStream stream = openFileInput(path);
with the below piece of code, I'm able to create a new file called output.txt and i'm able to write data. Problem is this file gets recreated once i close my app and then open my app again. As because i create this in onCreate().
But i would like to have the file created only once and then i would like to append the data there after.
private File outputFile = null;
FileOutputStream fOut = null;
OutputStreamWriter osw = null;
#Override
public void onCreate(Bundle savedInstanceState) {
....
if(outputFile == null)
outputFile = new File("/storage/new/output.txt");
if(osr==null){
try {
osr = new FileOutputStream(outputFile);
out = new DataOutputStream(osr);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
.....
try {
out.writeBytes(data);
out.flush();
//out.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Try setting the append flag to true when constructing your FileOutputStream
osr = new FileOutputStream(outputFile, true);
Try,
FileOutputStream fileOut = openFileOutput(outputFile, MODE_APPEND);
OutputStreamWriter osw = new OutputStreamWriter(fileOut);
osw.writeBytes(data);
osw.flush();