Writing arrayList <class> to file [duplicate] - java

This question already has answers here:
Unfortunately MyApp has stopped. How can I solve this?
(23 answers)
Closed 8 years ago.
I am new to android app development and I tried to write an arrayList to a file, but I've been getting problems when attempting to do that in my code:
public class AddActivity extends Activity implements Serializable {
/**
*
*/
private static final long serialVersionUID = 1L;
public transient Context ctx;
private final String filename = "Accounts";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add);
final EditText name = (EditText) findViewById(R.id.name);
final EditText username = (EditText) findViewById(R.id.username);
final EditText password = (EditText) findViewById(R.id.password);
final EditText type = (EditText) findViewById(R.id.type);
Button add = (Button) findViewById(R.id.add);
add.setOnClickListener(new View.OnClickListener() {
#SuppressWarnings("unchecked")
public void onClick(View arg0) {
String n = name.getText().toString();
String u = username.getText().toString();
String p = password.getText().toString();
String t = type.getText().toString();
Account newAccount = new Account (n, u , p, t);
ArrayList<Account> accounts;
String filePath = getFilesDir().getPath().toString() + "/" + filename;
File fl = new File(filePath);
try {
if (fl.exists()){
FileInputStream fis = ctx.openFileInput(filename);
ObjectInputStream oi = new ObjectInputStream(fis);
accounts = (ArrayList<Account>) oi.readObject();
accounts.add(newAccount);
oi.close();
fis.close();
fl.delete();
}else{
accounts = new ArrayList<Account>();
accounts.add(newAccount);
}
fl.createNewFile();
FileOutputStream fos = (openFileOutput(filename, Context.MODE_PRIVATE));
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(accounts);
oos.flush();
oos.close();
fos.close();
} catch (IOException e) {
Log.e("InternalStorage", e.getMessage());
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
});
}
}
My logCat says this:
05-20 18:56:23.782: E/AndroidRuntime(2242): FATAL EXCEPTION: main
05-20 18:56:23.782: E/AndroidRuntime(2242): Process: com.chenw15.accountmanager, PID: 2242
05-20 18:56:23.782: E/AndroidRuntime(2242): java.lang.NullPointerException
05-20 18:56:23.782: E/AndroidRuntime(2242): at com.chenw15.accountmanager.AddActivity$1.onClick(AddActivity.java:56)
05-20 18:56:23.782: E/AndroidRuntime(2242): at android.view.View.performClick(View.java:4438)
05-20 18:56:23.782: E/AndroidRuntime(2242): at android.view.View$PerformClick.run(View.java:18422)
05-20 18:56:23.782: E/AndroidRuntime(2242): at android.os.Handler.handleCallback(Handler.java:733)
05-20 18:56:23.782: E/AndroidRuntime(2242): at android.os.Handler.dispatchMessage(Handler.java:95)
05-20 18:56:23.782: E/AndroidRuntime(2242): at android.os.Looper.loop(Looper.java:136)
05-20 18:56:23.782: E/AndroidRuntime(2242): at android.app.ActivityThread.main(ActivityThread.java:5017)
05-20 18:56:23.782: E/AndroidRuntime(2242): at java.lang.reflect.Method.invokeNative(Native Method)
05-20 18:56:23.782: E/AndroidRuntime(2242): at java.lang.reflect.Method.invoke(Method.java:515)
05-20 18:56:23.782: E/AndroidRuntime(2242): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
05-20 18:56:23.782: E/AndroidRuntime(2242): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
05-20 18:56:23.782: E/AndroidRuntime(2242): at dalvik.system.NativeStart.main(Native Method)
Every time I click my add button, I get an error that says "Unfortunately, (App name) has stopped". Please help. Thanks.

I think you can also try below code for writing the list in file:
File myfile = getFileStreamPath(FileName);
try {
if (myfile.exists() || myfile.createNewFile()) {
FileOutputStream fos = openFileOutput(FileName, MODE_PRIVATE);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(masterlistrev);
fos.close();
}
} catch (Exception e) {
e.printStackTrace();
}

Related

How to rectify this error iin Recyclerview with database

When i am trying to display the contacts in card view when i click on Button it shows fatal exception error it doesnot display cardview anyone can solve this programming with brillliance and another error is it show only one cardview when i click on again the app will be strucked?
Showcontacts.java
public class ShowContacts extends Activity
{
private SQLiteDatabase db;
DbOperations doo;
private List<Contacts> contactsList;
private RecyclerView rv;
private Cursor c;
String names,email,address;
int phone;
String read_query = "select * from"+ ContactsTask.ContactsEntry.TABLE_NAME;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.recycle_layout);
doo = new DbOperations(this);
openDatabase();
rv = (RecyclerView)findViewById(R.id.recyclerview);
initializeData();
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
rv.setLayoutManager(linearLayoutManager);
rv.setHasFixedSize(true);
ContactAdapter cc = new ContactAdapter(contactsList);
rv.setAdapter(cc);
}
public void initializeData() {
contactsList = new ArrayList<>();
c = db.rawQuery(read_query,null);
c.moveToFirst();
while (!c.isLast())
{
names = c.getString(0);
phone = c.getInt(1);
email = c.getString(2);
address = c.getString(3);
contactsList.add(new Contacts(names,phone,email,address));
}
c.isLast();
names = c.getString(0);
phone = c.getInt(1);
email = c.getString(2);
address = c.getString(3);
contactsList.add(new Contacts(names,phone,email,address));
}
private void openDatabase() {
db = openOrCreateDatabase("contactDB", Context.MODE_PRIVATE,null);
}
}
Logacat error
06-28 08:57:43.107 568-568/com.example.anilkumar.contactstask E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.anilkumar.contactstask/com.example.anilkumar.contactstask.ShowContacts}: android.database.sqlite.SQLiteException: near "fromcontacts": syntax error: , while compiling: select * fromcontacts
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
at android.app.ActivityThread.access$600(ActivityThread.java:123)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4424)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.database.sqlite.SQLiteException: near "fromcontacts": syntax error: , while compiling: select * fromcontacts
at android.database.sqlite.SQLiteCompiledSql.native_compile(Native Method)
at android.database.sqlite.SQLiteCompiledSql.<init>(SQLiteCompiledSql.java:68)
at android.database.sqlite.SQLiteProgram.compileSql(SQLiteProgram.java:143)
at android.database.sqlite.SQLiteProgram.compileAndbindAllArgs(SQLiteProgram.java:361)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:127)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:94)
at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:53)
at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:47)
at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1564)
at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1538)
at com.example.anilkumar.contactstask.ShowContacts.initializeData(ShowContacts.java:44)
at com.example.anilkumar.contactstask.ShowContacts.onCreate(ShowContacts.java:34)
at android.app.Activity.performCreate(Activity.java:4466)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981) 
at android.app.ActivityThread.access$600(ActivityThread.java:123) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147) 
at android.os.Handler.dispatchMessage(Handler.java:99) 
at android.os.Looper.loop(Looper.java:137) 
at android.app.ActivityThread.main(ActivityThread.java:4424) 
at java.lang.reflect.Method.invokeNative(Native Method) 
Another logact error
06-28 13:14:40.552 11252-11261/com.example.anilkumar.contactstask E/SQLiteDatabase: close() was never explicitly called on database '/data/data/com.example.anilkumar.contactstask/databases/contactDB'
android.database.sqlite.DatabaseObjectNotClosedException: Application did not close the cursor or database object that was opened here
at android.database.sqlite.SQLiteDatabase.<init>(SQLiteDatabase.java:1943)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:1007)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:986)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:962)
at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:1043)
at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:1036)
at android.app.ContextImpl.openOrCreateDatabase(ContextImpl.java:761)
at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:215)
at com.example.anilkumar.contactstask.ShowContacts.openDatabase(ShowContacts.java:66)
at com.example.anilkumar.contactstask.ShowContacts.onCreate(ShowContacts.java:33)
at android.app.Activity.performCreate(Activity.java:4466)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
at android.app.ActivityThread.access$600(ActivityThread.java:123)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4424)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
Just update
String read_query = "select * from"+ ContactsTask.ContactsEntry.TABLE_NAME;
to
String read_query = "select * from "+ ContactsTask.ContactsEntry.TABLE_NAME;
Always close cursor. update your initializeData method
public void initializeData() {
try {
contactsList = new ArrayList<>();
try{
c = db.rawQuery(read_query,null);
c.moveToFirst();
while (!c.isLast())
{
names = c.getString(0);
phone = c.getInt(1);
email = c.getString(2);
address = c.getString(3);
contactsList.add(new Contacts(names,phone,email,address));
}
c.isLast();
names = c.getString(0);
phone = c.getInt(1);
email = c.getString(2);
address = c.getString(3);
contactsList.add(new Contacts(names,phone,email,address));
} catch (Exception e) {
// exception handling
} finally {
if(c != null){
c.close();
}
}
}

Cannot save files to SDcard android app

Im having a problem saving/ creating a file on my sdcard to save text to, i am trying to check if the file is created and if not create it, then write certain data to it on button click. Here is my code and error output:
This is the error output:
java.lang.RuntimeException: Unable to start activity ComponentInfo{ibettergetagoodgradeforthisorillbepissed.sciencefair.beta.mmmeds.com.mmmeds/ibettergetagoodgradeforthisorillbepissed.sciencefair.beta.mmmeds.com.mmmeds.MainActivity}: java.lang.IllegalArgumentException: File /sdcard/output.txt contains a path separator
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2187)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2236)
at android.app.ActivityThread.access$800(ActivityThread.java:138)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1199)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5034)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1270)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1086)
at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:132)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.IllegalArgumentException: File /sdcard/output.txt contains a path separator
at android.app.ContextImpl.makeFilename(ContextImpl.java:2165)
at android.app.ContextImpl.getFileStreamPath(ContextImpl.java:964)
at android.content.ContextWrapper.getFileStreamPath(ContextWrapper.java:195)
at ibettergetagoodgradeforthisorillbepissed.sciencefair.beta.mmmeds.com.mmmeds.MainActivity.onCreate(MainActivity.java:207)
at android.app.Activity.performCreate(Activity.java:5231)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2151)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2236)
            at android.app.ActivityThread.access$800(ActivityThread.java:138)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1199)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5034)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
and here is the code for the file saving:
String SDRoot = Environment.getExternalStorageDirectory().getPath();
final File output = getFileStreamPath(SDRoot + "/output.txt");
if(!output.exists()){
try {
output.createNewFile();
Context context = getApplicationContext();
CharSequence text = "Output File Created!";
int duration = Toast.LENGTH_LONG;
Toast fileCreated = Toast.makeText(context, text, duration);
fileCreated.show();
} catch (IOException e) {
Context context = getApplicationContext();
CharSequence text = "Output File Not Created!";
int duration = Toast.LENGTH_LONG;
Toast fileNotCreated = Toast.makeText(context, text, duration);
fileNotCreated.show();
e.printStackTrace();
}
}
Button addbutton = (Button)findViewById(R.id.addMeds);
addbutton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
String outputLine = medOut.toString() + doseOut.getText() + dayout.getText() + timeOut.getText();
try {
FileOutputStream fOut = new FileOutputStream(output);
OutputStreamWriter myOutputStreamWriter = new OutputStreamWriter(fOut);
myOutputStreamWriter.append(outputLine);
myOutputStreamWriter.flush();
myOutputStreamWriter.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
Toast.makeText(getBaseContext(), e.getMessage(),
Toast.LENGTH_SHORT).show();
} catch (IOException e) {
e.printStackTrace();
Toast.makeText(getBaseContext(), e.getMessage(),
Toast.LENGTH_SHORT).show();
}
}
});
}
http://developer.android.com/reference/android/content/Context.html#getFileStreamPath(java.lang.String)
Parameters : name The name of the file for which you would like to get its path.
If you give a path (containing "/") instead, it will crash as you have already noticed.
Besides, this function applies only for your application private files, created with openFileOuput for instance.
http://developer.android.com/reference/android/content/Context.html#openFileOutput(java.lang.String, int)
Just do like this :
String SDRoot = Environment.getExternalStorageDirectory().getPath();
final File output = new File(SDRoot + "/output.txt");

Fatal Error On main Thread

I am receiving this fatal Error, when I try to access one particular function zipIt().
It doesn't matter from where I try to access it I always receive this error. This function simply zips a folder but program don't even go inside this function.
Logcat is displayed below:
Process: com.test.shahid, PID: 14839
java.lang.IllegalStateException: Could not execute method of the activity
at android.view.View$1.onClick(View.java:3823)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5050)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1264)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1080)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at android.view.View$1.onClick(View.java:3818)
            at android.view.View.performClick(View.java:4438)
            at android.view.View$PerformClick.run(View.java:18422)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5050)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1264)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1080)
            at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at java.io.File.fixSlashes(File.java:185)
at java.io.File.<init>(File.java:134)
at java.io.FileOutputStream.<init>(FileOutputStream.java:128)
at java.io.FileOutputStream.<init>(FileOutputStream.java:117)
at com.test.shahid.MainActivity.zipIt(MainActivity.java:170)
at com.test.shahid.MainActivity.dispatchTakePictureIntent(MainActivity.java:490)
at com.test.shahid.MainActivity.onClickPhoto(MainActivity.java:468)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at android.view.View$1.onClick(View.java:3818)
            at android.view.View.performClick(View.java:4438)
            at android.view.View$PerformClick.run(View.java:18422)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5050)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1264)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1080)
            at dalvik.system.NativeStart.main(Native Method)
05-23 09:48:22.023 14839-14839/com.test.shahid I/Process﹕ Sending signal. PID: 14839 SIG: 9
Here is the function and variables associated with this function.
private static final File INPUT_FOLDER = Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_PICTURES);
private static final String ZIPPED_FOLDER = Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_PICTURES).toString();
protected void zipIt(File inputFolder, String zipFilePath) {
try {
FileOutputStream fileOutputStream = new FileOutputStream(zipFilePath);
ZipOutputStream zipOutputStream = new ZipOutputStream(fileOutputStream);
String myname =inputFolder.toString();
ZipEntry folderZipEntry = new ZipEntry(myname);
zipOutputStream.putNextEntry(folderZipEntry);
File[] contents = inputFolder.listFiles();
for (File f : contents) {
if (f.isFile())
zipFile(f, zipOutputStream);
}
zipOutputStream.closeEntry();
zipOutputStream.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
protected void zipFile(File inputFile, ZipOutputStream zipOutputStream) {
try { // A ZipEntry represents a file entry in the zip archive
// We name the ZipEntry after the original file's name
ZipEntry zipEntry = new ZipEntry(inputFile.getName());
zipOutputStream.putNextEntry(zipEntry);
FileInputStream fileInputStream = new FileInputStream(inputFile);
byte[] buf = new byte[1024];
int bytesRead;
// Read the input file by chucks of 1024 bytes
// and write the read bytes to the zip stream
while ((bytesRead = fileInputStream.read(buf)) > 0) {
zipOutputStream.write(buf, 0, bytesRead);
}
// close ZipEntry to store the stream to the file
zipOutputStream.closeEntry();
System.out.println("Regular file :" + inputFile.getCanonicalPath() + " is zipped to archive :" + ZIPPED_FOLDER);
} catch (IOException e) {
e.printStackTrace();
}
}
Well this is from where i am calling this function. I called this function just to check otherwise i have called this function from button and from several other functions. But nothing works.
public void onSync(View v) throws JSONException, IOException {
zipIt(INPUT_FOLDER, ZIPPED_FOLDER);
if (!isConnected()) {
AlertDialog.Builder mBuilder = new Builder(this);
mBuilder.setMessage("Please Enable Wifi to use this service");
mBuilder.setTitle("Enable WIFI");
mBuilder.setCancelable(false);
mBuilder.setPositiveButton("Settings",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
Intent i = new Intent(
Settings.ACTION_WIFI_SETTINGS);
startActivity(i);
}
}
);
mBuilder.setNegativeButton("Cancel",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// This code might cause problem so check when
// device is available
MainActivity.this.finish();
}
}
);
// create alert dialog
AlertDialog alertDialog = mBuilder.create();
// show it
alertDialog.show();
tvIsConnected.setText("You are NOT conncted");
// Intent myIntent = new
// Intent(Settings.ACTION_WIFI_SETTINGS);
// startActivity(myIntent);
return;
}
tvIsConnected.setBackgroundColor(0xFF00CC00);
tvIsConnected.setText("You are conncted");
handler.sendEmptyMessage(MSG_SYNC);
}
NullPointerException
Do you have "WriteExternalStorage" permision in your manifest?
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
Did you check the file path?
Environment.getExternalStorageDirectory() + "/some_foulder/file.txt"

Gson and Google

I have the following code:
public String test(){
URL url = null;
try {
url = new URL("http://api.heroesofnewerth.com/player_statistics/ranked/nickname/Hieratic/?token=0CZGH8ZI7UR8J2GN");
} catch (MalformedURLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
BufferedReader reader = null;
String x = "";
try {
reader = new BufferedReader(new InputStreamReader(url.openStream(), "UTF-8"));
for (String line; (line = reader.readLine()) != null;) {
System.out.println(line);
x = line;
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally{
if (reader !=null) try{reader.close();} catch (IOException ignore) {
}{}
}
JsonElement root = new JsonParser().parse(x);
return x;
}
}
now i want to insert the text into the following textView.
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_create_competetion);
TextView tv = (TextView) findViewById(R.id.competetion_text);
JsonCollector jc = new JsonCollector();
tv.setText(jc.test());
However when i try to run it. i get the following error:
FATAL EXCEPTION: main
E/AndroidRuntime(1800): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.konkurrencesigner/com.example.konkurrencesigner.CreateCompetetion}: android.os.NetworkOnMainThreadException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
E/AndroidRuntime(1800): at android.app.ActivityThread.access$600(ActivityThread.java:141)
E/AndroidRuntime(1800): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
E/AndroidRuntime(1800): at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(1800): at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime(1800): at android.app.ActivityThread.main(ActivityThread.java:5039)
E/AndroidRuntime(1800): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(1800): at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime(1800): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
E/AndroidRuntime(1800): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
E/AndroidRuntime(1800): at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime(1800): Caused by: android.os.NetworkOnMainThreadException
E/AndroidRuntime(1800): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117)
E/AndroidRuntime(1800): at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
E/AndroidRuntime(1800): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
E/AndroidRuntime(1800): at java.net.InetAddress.getAllByName(InetAddress.java:214)
E/AndroidRuntime(1800): at libcore.net.http.HttpConnection.<init>(HttpConnection.java:70)
E/AndroidRuntime(1800): at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
E/AndroidRuntime(1800): at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:340)
E/AndroidRuntime(1800): at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:87)
E/AndroidRuntime(1800): at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
E/AndroidRuntime(1800): at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:316)
E/AndroidRuntime(1800): at libcore.net.http.HttpEngine.connect(HttpEngine.java:311)
E/AndroidRuntime(1800): at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:290)
E/AndroidRuntime(1800): at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:240)
E/AndroidRuntime(1800): at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:282)
Can anyone tell me why this is happening?
please note that i have already added the following line in my android manifest:
<uses-permission android:name="android.permission.INTERNET" />
You are doing HTTP communication on the main thread, that's why you're getting a NetworkOnMainThreadException. Do it in a separate thread, using an AsyncTask would be an ideal solution, here's an example of how you could implement it:
private TextView tv;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_create_competetion);
tv = (TextView) findViewById(R.id.competetion_text);
JsonCollector jc = new JsonCollector();
// Create and execute a new AsyncTask, the TextView will
// be updated asynchronously when the task has finished.
updateTextView();
}
private void updateTextView() {
new AsyncTask<Void, Void, String>() {
#Override
/* Runs on a separate thread */
protected String doInBackground(Void... params) {
String result = null;
BufferedReader reader = null;
try {
URL url = new URL("http://api.heroesofnewerth.com/player_statistics/ranked/nickname/Hieratic/?token=0CZGH8ZI7UR8J2GN");
reader = new BufferedReader(new InputStreamReader(url.openStream(), "UTF-8"));
for (String line; (line = reader.readLine()) != null;) {
System.out.println(line);
result = line;
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException e) {
// Ignore
}
}
}
return result;
}
#Override
/* Runs on the UI/Main thread when doInBackground()
* has finished */
protected void onPostExecute(String result) {
if(result != null) {
// Update the TextView only if we got a result
// from the HTTP request
tv.setText(result);
}
}
}.execute();
}
If you need networking in main thread add these lines of code in the onCreate() method
StrictMode.ThreadPolicy policy =
new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);

App Crashes on Launch, Trying to see if file exist's for login screen

I'm creating a Class that checks to see if the file has been created (Has username and passwords.) and if it does it creates an intent to go to another class to read the data and check it againts a server via FTP. For some reason, I can't get it to work, I've tried everything and read every single web page I could, but no luck.
My Code:
public class LogIn extends Activity implements OnClickListener {
Button send;
EditText user;
EditText pass;
CheckBox staySignedIn;
FileOutputStream Fos;
String a;
String b;
String string = a;
String string2 = b;
String FILENAME = "userandpass";
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.login);
send = (Button) findViewById(R.id.bLogIn);
user = (EditText) findViewById(R.id.eTuser);
pass = (EditText) findViewById(R.id.eTpassword);
staySignedIn = (CheckBox) findViewById(R.id.Cbstay);
send.setOnClickListener(this);
if (staySignedIn.isChecked()) {
String a = user.getText().toString();
String b = pass.getText().toString();
File f = new File(FILENAME);
try {
Fos = openFileOutput(FILENAME, Context.MODE_PRIVATE);
Fos.write(string.getBytes());
Fos.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
File file = getBaseContext().getFileStreamPath(FILENAME);
if(file.exists());
Intent i = new Intent(LogIn.this, ChatService.class);
}
}
public void onClick(View v) {
// TODO Auto-generated method stub
switch (v.getId()) {
case R.id.bLogIn:
if (pass.length() == 0)
Toast.makeText(this,
"Try to type in your username and password again!",
Toast.LENGTH_LONG).show();
else if (user.length() == 0)
Toast.makeText(this,
"Try to type in your username and password again!",
Toast.LENGTH_LONG).show();
else {
String u = user.getText().toString();
String p = pass.getText().toString();
Bundle send = new Bundle();
send.putString("key", u);
send.putString("key1", p);
Intent a = new Intent(LogIn.this, logincheck.class);
a.putExtra("key", u);
a.putExtra("key1", p);
startActivity(a);
Toast.makeText(this, "Were signing you in!", Toast.LENGTH_LONG)
.show();
break;
}
}
}
}
LogCat:
01-19 11:37:17.601: W/dalvikvm(4411): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
01-19 11:37:17.621: E/AndroidRuntime(4411): FATAL EXCEPTION: main
01-19 11:37:17.621: E/AndroidRuntime(4411): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.gta5news.bananaphone/com.gta5news.bananaphone.LogIn}: java.lang.NullPointerException
01-19 11:37:17.621: E/AndroidRuntime(4411): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
01-19 11:37:17.621: E/AndroidRuntime(4411): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
01-19 11:37:17.621: E/AndroidRuntime(4411): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
01-19 11:37:17.621: E/AndroidRuntime(4411): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
01-19 11:37:17.621: E/AndroidRuntime(4411): at android.os.Handler.dispatchMessage(Handler.java:99)
01-19 11:37:17.621: E/AndroidRuntime(4411): at android.os.Looper.loop(Looper.java:123)
01-19 11:37:17.621: E/AndroidRuntime(4411): at android.app.ActivityThread.main(ActivityThread.java:4627)
01-19 11:37:17.621: E/AndroidRuntime(4411): at java.lang.reflect.Method.invokeNative(Native Method)
01-19 11:37:17.621: E/AndroidRuntime(4411): at java.lang.reflect.Method.invoke(Method.java:521)
01-19 11:37:17.621: E/AndroidRuntime(4411): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
01-19 11:37:17.621: E/AndroidRuntime(4411): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
01-19 11:37:17.621: E/AndroidRuntime(4411):
at dalvik.system.NativeStart.main(Native Method)
01-19 11:37:17.621: E/AndroidRuntime(4411): Caused by: java.lang.NullPointerException
01-19 11:37:17.621: E/AndroidRuntime(4411): at com.gta5news.bananaphone.LogIn.onCreate(LogIn.java:55)
01-19 11:37:17.621: E/AndroidRuntime(4411): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
01-19 11:37:17.621: E/AndroidRuntime(4411): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
If line 55 is
Fos.write(string.getBytes());
then either Fos or string is uninitialized. Given that string is initialized to a which is itself uninitialized, that explains it. You need to assign a proper value to string.
Fos = openFileOutput(FILENAME, Context.MODE_PRIVATE);
It seems for some reason openFileOutput returning null which makes Fos null, which is throwing NullPointerException.
Add
if(Fos != null) {
Fos.write(string.getBytes());
Fos.close();
} check.
OR catch NullpointerException.

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