I have been working on this for a few weeks now a little bit at a time. This is an android app i am developing for multiple versions of Samsung tablets. I need to create a file and add text to it. I cannot do either. I have 2 different methods to add text using different text writers to add text to a file. Here is my code:
public void addTextToFile(String text) {
File logFile = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PODCASTS), "MyFile.csv");
if (!logFile.exists()) {
try {
logFile.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
try {
BufferedWriter buf = new BufferedWriter(new FileWriter(logFile, true));
buf.append(text);
buf.newLine();
buf.close();
} catch (IOException e) {
e.printStackTrace();
}
}
public void write(String data){
OutputStream os;
OutputStreamWriter osw;
data += "\n";
try {
os = new FileOutputStream(file, true);
osw = new OutputStreamWriter(os);
osw.write(data);
osw.flush();
osw.close();
} catch (Exception e) {
e.printStackTrace();
}
}
Found my error, I did research at the beginning and thought i did not need permission to create a publicly view-able file, I gave myself permission in the android manifest like so:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
Related
I've found a bunch of similiar questions there, but all the proposed solutions already exist in my code, so...
I have the following routine being called from different places in my app:
static private void writeToFile(String data) {
File file = new File("sdcard/output.txt");
if (!file.exists()) {
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
BufferedWriter bw = null;
try {
FileWriter fw = new FileWriter(file, true);
bw = new BufferedWriter(fw);
bw.append(new Date().toString() + " " + data);
bw.newLine();
}
catch (IOException e) {
e.printStackTrace();
}
finally {
try {
if(bw != null) {
bw.close();
}
} catch(Exception e) {
e.printStackTrace();
}
}
}
Sometimes after a while strings stop to be added to a file. I've presumed it's something about syncronization - but once I've succeeded to catch it in debug mode and stepped all over the routine - every statement is executed without any exceptions.
Can you, please, tell what's wrong with my code?
in one of the activities when a button is pressed i want to create a file on the extran storage. so i wrote
the below code to do so.
but in the end the file is created but empty..why?
code:
public void tx(byte[] data) {
Log.w(TAG, CSubTag.bullet("tx"));
File file = new File(Environment.getExternalStorageDirectory() + File.separator + "test.txt");
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
try {
OutputStream os = new FileOutputStream(file);
BufferedOutputStream bos = new BufferedOutputStream(os);
try {
bos.write("data_stream".getBytes());
} catch (IOException e) {
e.printStackTrace();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
Please close the OutputStream and BufferedOutputStream inside finally block. Otherwise, the data will not be written.
Currently I'm developing an android app where the user has to click on a button this adds +1 to a count. After 100 there is another button which causes a reset of the count and increase the level and difficulty which is stored in another 2 "ints". Well its all working but I seriously have big problems with creating a save file.
-I gave me the permission via AndroidManifest.xml
-Tryed 3 other code examples
I did import everything that is necessary and the rest of the code is working
There has to be a mistake in this part of my code:
(my part for the Saving the "Stats")
save.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
try {
FileOutputStream savelvl = openFileOutput("savelvl.data", Context.MODE_PRIVATE);
savelvl.write(level);
savelvl.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
});
can anyone suggest an improvement to the code or tell me the mistake in saving the file to the internal storage?
I've had success with using a BufferedWriter instead of FileOutputStream, although I'm sure it could given a different setup. Below is some code with "FileOutputStream out", which I was trying to use initially, commented out.
BufferedWriter writer = null;
try {
writer = new BufferedWriter(new FileWriter(file,true));
//out = new FileOutputStream(file);
Log.i("file","file opened");
writer.write(someString);
//out.write(someString.getBytes());
Log.i("file","file written");
} catch (Exception e) {
Log.e("fileNotFound","file not found exception");
e.printStackTrace();
}/*
try {
out.write(someString.getBytes());
Log.i("file","file written");
Log.i("str2File",someString.getBytes().toString());
} catch (IOException e) {
Log.e("fileWrite","file write error");
e.printStackTrace();
}*/ finally {
try {
//out.getFD().sync();
//out.close();
writer.close();
Log.i("file","file closed");
} catch (Exception e) {
Log.e("closeError","error closing file");
e.printStackTrace();
}
}
You cannot flush your data. When you use writer you must call flush method after write method.
OutputStrem stream = ... // I cannot create new reference because "OutStream" class is abstract
stream.write(data, offset, length);
stream.flush();
stream.close();
I have this method supposed to read a file:
/* Read file's content */
private ArrayList<String> readFromFile() {
File file = new File("jokesBody1.bjk");
ArrayList<String> list = new ArrayList<String>();
try {
file.createNewFile();
ObjectInputStream ois = new ObjectInputStream( new FileInputStream( file ) );
try {
list = (ArrayList)ois.readObject();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
ois.close();
} catch (IOException e) {
Log.e("log activity", "Can not read file: " + e.toString());
}
return list;
}
When I call it, it returns:
02-16 06:15:32.686: E/log activity(1380): Can not read file: java.io.IOException: open failed: EROFS (Read-only file system)
Even, if the file is read only, why I can't read it? I really can't understand what is wroong. I have this premission in my manifest:
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
Can someone give me a clue? I know that I'm missing something small, but I really can't spot it.
Here is how I write the file:
/* Write content to a file */
private void writeToFile(ArrayList<String> list, Context cont) {
File file = new File("jokesBody1.bjk");
FileOutputStream fos;
if(list != null){
try {
fos = cont.openFileOutput("jokesBody1.bjk", Context.MODE_PRIVATE);
ObjectOutputStream out = new ObjectOutputStream(fos);
out.writeObject(list);
out.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}else{
try {
file.createNewFile();
fos = openFileOutput("jokesBody1.bjk",Context.MODE_PRIVATE);
ObjectOutputStream out = new ObjectOutputStream(fos);
out.writeObject("");
out.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
You are trying to create the file, which of course fails on a read-only file.
Remove this line:
file.createNewFile();
This is usually used to create a new empty file before writing to it. You really don't need it if you just want to read a file that already exists.
EDIT:
Just use this:
ObjectInputStream ois = new ObjectInputStream( context.openFileInput("jokesBody1.bjk"));
Of course, you'll also have to pass a Context to the function.
You can only use File with a full path. For accessing your private files, use Context, just as you do when saving the file.
Your full function should look like:
private ArrayList<String> readFromFile(Context context) {
ArrayList<String> list = new ArrayList<String>();
try {
ObjectInputStream ois = new ObjectInputStream( context.openFileInput("jokesBody1.bjk"));
try {
list = (ArrayList)ois.readObject();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
ois.close();
} catch (IOException e) {
Log.e("log activity", "Can not read file: " + e.toString());
}
return list;
}
You aren't specifying any path:
File file = new File("jokesBody1.bjk");
So, you are not saying the app WHERE to look for the file.
Maybe, you want to search it here?
Environment.getExternalStorageDirectory()
I am using the following method to read from the internal storage:
private void deserialize(ArrayList<Alias>arrayList) {
try {
FileInputStream fis = openFileInput(filename);
ObjectInputStream ois = new ObjectInputStream(fis);
arrayList = (ArrayList<Alias>)ois.readObject();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
It reads the content of the file "filename" to the "arrayList".
The "serialize" method is as follows:
void serialize(ArrayList<Alias>arrayList) {
FileOutputStream fos;
try {
fos = openFileOutput(filename, Context.MODE_PRIVATE);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(arrayList);
oos.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
The problem is that I whenever I run my program again, the "arrayList" is empty. So I guess I am opening the file in wrong input mode.
My aim is to first get the array from the file, then modify it within the app, and then write the modified array back to the file.
Can someone please help me with my problem?
Thanks!
Can you post your pice of your source code? I think the way which you used to parse file content get issue.
Read here:
Android ObjectInputStream docs
I read that the method readObject() read the next object...i this that you must iterate with something like this:
MediaLibrary obj = null;
while ((obj = (MediaLibrary)objIn.readObject()) != null) {
libraryFromDisk.add(obj);
}