When the user clicks the save button a text file should be created and the contents should be stored in the file, but my application just crashes when I do so.
public class newfile extends Activity {
public EditText textBox,textbox2;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.newfile);
Button save = (Button) findViewById(R.id.btnSave);
save.setOnClickListener(new View.OnClickListener(){
public void onClick(View v) {
textBox = (EditText) findViewById(R.id.txtText1);
textbox2 = (EditText) findViewById(R.id.fname);
String FILENAME = textbox2.getText().toString();
String value = textBox.getText().toString();
File("R.raw",value);
FileOutputStream fos=null ;
fos = openFileOutput(FILENAME, Context.MODE_PRIVATE);
try {
fos.write(((String) value).getBytes());
fos.flush();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
fos.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private void File(String string, String value) {
// TODO Auto-generated method stub
}
private FileOutputStream openFileOutput(String fILENAME,
int modePrivate) {
// TODO Auto-generated method stub
return null;
}
});
}
}
openFileOutput returns null? Mayby thats why your app chrashes?
Delete this line...
File("R.raw",value);
Delete these methods...
private void File(String string, String value) {
// TODO Auto-generated method stub
}
private FileOutputStream openFileOutput(String fILENAME,
int modePrivate) {
// TODO Auto-generated method stub
return null;
}
Surround this line...
fos = openFileOutput(FILENAME, Context.MODE_PRIVATE);
...with a try/catch block like so...
try {
fos = openFileOutput(FILENAME, Context.MODE_PRIVATE);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
Use getFilesDir() to get the absolute path of your application and use it to create a file in your application folder.
Otherwise, you don't have the right to create files everywhere.
http://developer.android.com/reference/android/content/Context.html#getFilesDir()
Related
I'm currently learning about IO and Async but am having issues. I'm following a guide, and according to the guide this is supposed to work. I have created an activity with a simple EditText, TextView, and 2 Buttons(save and load). I am trying to have the save button take the text in the EditText and save to internal storage, and the load button take whatever is saved and set the TextView as that. Everything works flawlessly when I put all the code to run in the UI thread, but if I change the code to have the UI thread call the Async class for the loading, nothing seems to happen.
**Packages and imports have been removed to save space.
public class InternalData extends Activity implements OnClickListener {
EditText etSharedData;
TextView tvDataResults;
FileOutputStream fos;
String FILENAME = "InternalString";
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.sharedpreferences);
setupVariables();
}
private void setupVariables() {
Button bSave = (Button) findViewById(R.id.bSave);
Button bLoad = (Button) findViewById(R.id.bLoad);
etSharedData = (EditText) findViewById(R.id.etSharedPrefs);
tvDataResults = (TextView) findViewById(R.id.tvLoadSharedPrefs);
bSave.setOnClickListener(this);
bLoad.setOnClickListener(this);
try {
fos = openFileOutput(FILENAME, Context.MODE_PRIVATE);
fos.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
switch (v.getId()) {
case R.id.bSave:
String sData = etSharedData.getText().toString();
try {
fos = openFileOutput(FILENAME, Context.MODE_PRIVATE);
fos.write(sData.getBytes());
fos.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
break;
case R.id.bLoad:
String sCollected = null;
FileInputStream fis = null;
try {
fis = openFileInput(FILENAME);
byte[] dataArray = new byte[fis.available()];
while(fis.read(dataArray) != -1){
sCollected = 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();
tvDataResults.setText(sCollected);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
break;
}
}
The previous code makes everything work, but the UI lags a bit when trying to load large strings. When I try to have an LoadSomeStuff(Async) class do the loading, it does absolutely nothing when I hit Load on my phone. Within the LoadSomeStuff class it has the doInBackground method open the file and read the data into a string then return that string, and the onPostExecute method set the TextView's text to the returned String. Here's the code:
The onClick method for load button has:
new LoadSomeStuff().execute(FILENAME);
LoadSomeStuff Class *Note: This class is declared within the InternalData class.
public class LoadSomeStuff extends AsyncTask<String, Integer, String>{
#Override
protected String doInBackground(String... arg0) {
// TODO Auto-generated method stub
String sCollected = null;
FileInputStream fis = null;
try {
fis = openFileInput(FILENAME);
byte[] dataArray = new byte[fis.available()];
while(fis.read(dataArray) != -1){
sCollected = 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();
return sCollected;
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return null;
}
protected void onPostExecute(String result){
tvDataResults.setText(result);
}
}
}
Any help is greatly appreciated, thanks!
It actually looks like I had an extra method or two(like onPreExecute) with no code in them and when I deleted them it starting working.
I'm trying to save and load a String to/from the internal storage in a way that allows the user to exit the app, even shut down the phone, but still access this String whenever the app is used.
When I exit the app it and re-enter, it will not load the String I stored previously. I need it to load the previous String even if I reboot the phone. Here is what I have so far:
EditText sharedData;
TextView dataResults;
FileOutputStream fos;
String FILENAME = "InternalString";
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.sharedpreferences);
setupVariables();
}
private void setupVariables() {
// TODO Auto-generated method stub
sharedData = (EditText) findViewById(R.id.editText_SharedPrefs);
dataResults = (TextView) findViewById(R.id.textView_LoadSharedPrefs);
Button save = (Button) findViewById(R.id.button_save);
Button load = (Button) findViewById(R.id.button_load);
save.setOnClickListener(this);
load.setOnClickListener(this);
try {
fos = openFileOutput(FILENAME, Context.MODE_PRIVATE);
fos.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
switch (v.getId()) {
case R.id.button_save:
String data = sharedData.getText().toString();
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();
}
break;
case R.id.button_load:
String collected = null;
FileInputStream fis = null;
try {
fis = openFileInput(FILENAME);
byte[] dataArray = new byte[fis.available()];
while(fis.read(dataArray) != -1){
collected = new String(dataArray);
}
dataResults.setText(collected);
} 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();
}
}
break;
}
}
Depending on what sort of "string" you're using you should use SharedPreferences rather than write files... unless it's a lot of data.
getSharedPreferences(getPackageName() , MODE_PRIVATE).edit().putString("myString").commit();
That will persist through phone powercycles. It will get lost if you uninstall the app however (which is probably a good thing).
Here's the Android doc for all the various data saving possibilities open to you...
Saving Stuff On Android
I need to save the barcode with timestamp and save that in a .csv file and send it to another device via Bluetooth. I am taking the barcode through SerialMagic Gear Keyboard option which take the barcode as an input
Problem: When the application run and i enter data, when the file is received by another device the file only contains the last entry.
I am sure that I am making some mistake in the structure of the program. If so kindly indicate where.
And sorry for the long code.
package com.android.app;
public class MainActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Timestamp for file name e.g. Data_7-19-2012
SimpleDateFormat s1 = new SimpleDateFormat("MM-dd-yyyy_hh:mm:ss");
final String format1 = s1.format(new Date());
//Creating file name
final String FileName = "Data_"+format1+".csv";
final EditText addbarcode = (EditText) findViewById(R.id.editText1);
//getting file directory
final File dir = getFilesDir();
final File shareFile = new File(dir, FileName);
addbarcode.setOnKeyListener(new OnKeyListener()
{
public boolean onKey(View v, int keyCode, KeyEvent event)
{
if (event.getAction() == KeyEvent.ACTION_DOWN)
{
switch (keyCode)
{
//case KeyEvent.KEYCODE_DPAD_CENTER:
case KeyEvent.KEYCODE_ENTER:
//to get Timestamp
SimpleDateFormat s = new SimpleDateFormat("MM-dd-yyyy hh:mm:ss");
String format = s.format(new Date());
//get barcode in a variable
Editable barcode = addbarcode.getText();
final String DATASTRING = new String(""+barcode+","+format+"\n");
FileOutputStream fOut = null;
try {
fOut = openFileOutput(FileName , MODE_WORLD_READABLE);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
OutputStreamWriter osw = new OutputStreamWriter(fOut);
// Write the string to the file
try {
osw.write(DATASTRING);
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {
osw.flush();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
osw.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
/* ensure that everything is
* really written out and close */
//For showing data recived on screen
FileInputStream fIn = null;
try {
fIn = openFileInput(FileName);
} catch (FileNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
InputStreamReader isr = new InputStreamReader(fIn);
//Prepare a char-Array that will
//* hold the chars we read back in.
char[] inputBuffer = new char[DATASTRING.length()];
// Fill the Buffer with data from the file
try {
isr.read(inputBuffer);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// Transform the chars to a String
String readString = new String(inputBuffer);
TextView etData= (TextView)findViewById(R.id.textView3);
etData.setText(readString);
//Clear the editview for new entries
addbarcode.setText("");
return true;
default:
break;
}
}
return false;
}
});
final Button button = (Button) findViewById(R.id.button1);
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Uri u1 = null;
u1 = Uri.fromFile(shareFile);
Intent sendIntent = new Intent(Intent.ACTION_SEND);
sendIntent.putExtra(Intent.EXTRA_SUBJECT, "Person Details");
sendIntent.putExtra(Intent.EXTRA_STREAM, u1);
sendIntent.setType("text/csv");
startActivity(sendIntent);
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
You need to use the MODE_APPEND flag in openFileOutput, otherwise the old file contents gets overwritten by default.
The code creates a text file in local memory, but how do I get all files created by my application in a list view:
public class newfile extends Activity {
public EditText textBox,textbox2;
FileOutputStream fos=null;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.newfile);
Button save = (Button) findViewById(R.id.btnSave);
save.setOnClickListener(new View.OnClickListener(){
public void onClick(View v) {
textBox = (EditText) findViewById(R.id.txtText1);
textbox2 = (EditText) findViewById(R.id.fname);
String FILENAME = textbox2.getText().toString();
String value = textBox.getText().toString();
try{
fos = openFileOutput(FILENAME,MODE_WORLD_WRITEABLE);
}
catch(IOException e)
{
e.printStackTrace();
}
byte[] buffer = value.getBytes();
try {
fos.write(buffer);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
fos.flush();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
fos.close();
Toast.makeText(getBaseContext(), "File saved successfully!", Toast.LENGTH_LONG).show();
finish();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
}
}
You can get a list all application files using Context.fileList. Then use ArrayAdapter to populate your list view
I am an amateur programmer developing for android. I am just trying get the basics down right now, but I am having an error and I don't know why.
I am creating a activity that has a save and a load button, which using the fileOutputStream and fileInputStream to achieve this task.
The problem I am having is if I hit the load button the first time I use the activity, my application crashes. Can anyone help me with how to skip the load section if the file hasn't been created yet? What should I use within my if statement.
Thanks a ton, here is my code:
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class InternalData extends Activity implements OnClickListener {
String FILENAME = "InternalString";
EditText sharedData;
TextView dataResults;
FileOutputStream fos;
String d;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.sharedpreferences);
Button save = (Button) findViewById(R.id.bSave);
Button load = (Button) findViewById(R.id.bLoad);
sharedData = (EditText) findViewById(R.id.etSharedPrefs);
dataResults = (TextView) findViewById(R.id.tvLoadSharedPrefs);
save.setOnClickListener(this);
load.setOnClickListener(this);
try {
fos = openFileOutput(FILENAME, Context.MODE_PRIVATE);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void onClick(View v) {
// TODO Auto-generated method stub
switch (v.getId()) {
case R.id.bSave:
d = sharedData.getText().toString();
try {
fos.write(d.getBytes());
fos.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
break;
case R.id.bLoad:
FileInputStream fis = null;
try {
if (openFileInput(FILENAME) != null){
fis = openFileInput(FILENAME);
byte[] data = new byte[fis.available()];
while(fis.read(data) != -1){
String readData = new String(data);
dataResults.setText(readData);
}}
} 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();
}
}
break;
}
}
}
Thanks for the help Lukas, I have updated my code, and I was wondering if you could look it over to make sure I am using the AsyncTask properly. Thanks again!
public class InternalData extends Activity implements OnClickListener {
String FILENAME = "InternalString";
EditText sharedData;
TextView dataResults;
FileOutputStream fos;
String d;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.sharedpreferences);
Button save = (Button) findViewById(R.id.bSave);
Button load = (Button) findViewById(R.id.bLoad);
sharedData = (EditText) findViewById(R.id.etSharedPrefs);
dataResults = (TextView) findViewById(R.id.tvLoadSharedPrefs);
save.setOnClickListener(this);
load.setOnClickListener(this);
}
public void onClick(View v) {
// TODO Auto-generated method stub
switch (v.getId()) {
case R.id.bSave:
d = sharedData.getText().toString();
try {
fos = openFileOutput(FILENAME, Context.MODE_PRIVATE);
fos.write(d.getBytes());
fos.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
break;
case R.id.bLoad:
AsyncTask<String, Integer, String> dat = new loadInternalData().execute(FILENAME);
break;
}
}
public class loadInternalData extends AsyncTask<String, Integer, String> {
#Override
protected String doInBackground(String... params) {
// TODO Auto-generated method stub
FileInputStream fis = null;
String collected = null;
try {
fis = openFileInput(FILENAME);
byte[] data = new byte[fis.available()];
while (fis.read(data) != -1){
collected = new String(data);
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
try {
fis.close();
return collected;
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return collected;
}
#Override
protected void onPostExecute( String result )
{
super.onPostExecute(result);
Log.i( "InteralStorage", "onPostExecute(): " + result );
dataResults.setText( result );
}
}
}
You are calling openFileInput twice. Just call it once.
Instead of this
if (openFileInput(FILENAME) != null){
fis = openFileInput(FILENAME);
}
Do this:
fis = openFileInput(FILENAME);
if (fis != null) {
// Read file
}
If you execute something on the UI-Thread, it shouldn't take longer then 5 seconds or an ANR will be triggered.
If you want to do something that might take longer then those 5 seconds, you'll want to do it in a Service or an AsyncTask.
Also, if your App gets force closed and you don't know why, you should always have a look at the LogCat output which can be shown in Eclipse. Also, you should include it with every question you ask here (about Android).