Develop Reference

How to solve Function1 (Context) in Function1 cannot be applied to ()

I have the following problems:
I would like to call a function from another class so I added this line of code
Function1 func = new Function1(); and I get an error saying
Function1 (Context) in Function1 cannot be applied to ()
Furthermore, relating to this function and its error, I intend calling the aforementioned function which takes a JSON object and a Filename as parameters and it returns a file, however, when I enter it, I get the following error
Wrong 2nd argument type, found Java.lang.String required Java.io.File
The code in question is this:
JSONObject export = jsonArray1.getJSONObject(index);
File file = func.exportToFile(export, "Export.json");
The fuction in question starts like this:
public void exportToFile(JSONObject objectToExport, File fN)
{
String output = objectToExport.toString();
file_ = fN;
if (!file_.exists()) {
try {
file_.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
try{
FileOutputStream fOut = new FileOutputStream(file_);
fOut.write(output.getBytes());
fOut.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
N.B.: I have tried to call the function like this:
File file = func.exportToFile(export, func.file);
but I only get the error saying incompatible types
Required Java.io.file
Found Void
What have I done wrong?

this func.exportToFile(export, func.file); will not return anything since exportToFile it's a void method .
change your method to make it return file this way :
public File exportToFile(JSONObject objectToExport, File fN) {
String output = objectToExport.toString();
file_ = fN;
if (!file_.exists()) {
try {
file_.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
try{
FileOutputStream fOut = new FileOutputStream(file_);
fOut.write(output.getBytes());
fOut.close();
return file_;
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}

Android: File not found exception, it worked in the first time?

I am performing a project, where so far in the discipline, we can not use database to persist the data. I am persisting the data in .tmp files. The first time I persisted the list of doctors, and it worked, but now that I'm trying to persist the patient user data, but this error happens, that file is not found.
These are my load, anda save methods in the class "SharedResources":
public void loadUserPatient(Context context) {
FileInputStream fis1;
try {
fis1 = context.openFileInput("patient.tmp");
ObjectInputStream ois = new
ObjectInputStream(fis1);
userPatient = (UserPatient) ois.readObject();
ois.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch(IOException e) {
e.printStackTrace();
} catch(ClassNotFoundException e) {
e.printStackTrace();
}
}
public void saveUserPatient(Context context) {
FileOutputStream fos1;
try {
fos1 = context.openFileOutput("patient.tmp",
Context.MODE_PRIVATE);
ObjectOutputStream oos =
new ObjectOutputStream(fos1);
oos.writeObject(userPatient);
oos.close();
} catch (Exception e) {
e.printStackTrace();
}
}
here is the whole class: https://ideone.com/f3c74u
the error is happening on line 16 of MainActivity:
SharedResources.getInstance().loadUserPatient(this);
here is the whole class "Main": https://ideone.com/OyiljP
And I think this error is ocurring because of the 52nd line of the UserPatientAdd class:
SharedResources.getInstance().getUserPatient();
because when I work with an ArrayList, I put an add at the end of the line, like:SharedResources.getInstance().getDoctors().add(doctor);
And I get confused on how to proceed when I deal only with a user.
This is the whole UserPatientAdd class: https://ideone.com/clUSa3
How can I solve this problem?

You need to set the UserPatient using something like this
In your SharedResources class, create a new method:
public void setUserPatient(UserPatient user) {
userPatient = user;
}
Then in your UserPatientAdd class set the new object:
UserPatient userPatient = new UserPatient (birth, name, bloodType, bloodPressure, cbpm, vacinesTaken, vacinesToBeTaken,
allergies,weight, height, surgeries, desease);
SharedResources.getInstance().setUserPatient(userPatient);
Done

file.delete() wont delete file, java

Okay, this is going to be a bit long. So I made a junit test class to test my program. I wanted to test if a method that uses a Scanner to read a file into the program threw and exception, if the file didn't exist like this:
#Test
public void testLoadAsTextFileNotFound()
{
File fileToDelete = new File("StoredWebPage.txt");
if(fileToDelete.delete()==false) {
System.out.println("testLoadAsTextFileNotFound - failed");
fail("Could not delete file");
}
try{
assertTrue(tester.loadAsText() == 1);
System.out.println("testLoadAsTextFileNotFound - passed");
} catch(AssertionError e) {
System.out.println("testLoadAsTextFileNotFound - failed");
fail("Did not catch Exception");
}
}
But the test fails at "could not delete file", so I did some searching. The path is correct, I have permissions to the file because the program made it in the first place. So the only other option would be, that a stream to or from the file is still running. So I checked the method, and the other method that uses the file, and as far as I can, both streams are closed inside the methods.
protected String storedSite; //an instance variable
/**
* Store the instance variable as text in a file
*/
public void storeAsText()
{
PrintStream fileOut = null;
try{
File file = new File("StoredWebPage.txt");
if (!file.exists()) {
file.createNewFile();
}
fileOut = new PrintStream("StoredWebPage.txt");
fileOut.print(storedSite);
fileOut.flush();
fileOut.close();
} catch(Exception e) {
if(e instanceof FileNotFoundException) {
System.out.println("File not found");
}
fileOut.close();
} finally {
if(fileOut != null)
fileOut.close();
}
}
/**
* Loads the file into the program
*/
public int loadAsText()
{
storedSite = ""; //cleansing storedSite before new webpage is stored
Scanner fileLoader = null;
try {
fileLoader = new Scanner(new File("StoredWebPage.txt"));
String inputLine;
while((inputLine = fileLoader.nextLine()) != null)
storedSite = storedSite+inputLine;
fileLoader.close();
} catch(Exception e) {
if(e instanceof FileNotFoundException) {
System.out.println("File not found");
return 1;
}
System.out.println("an Exception was caught");
fileLoader.close();
} finally {
if(fileLoader!=null)
fileLoader.close();
}
return 0; //return value is for testing purposes only
}
I'm out of ideas. Why can't I delete my file?
EDIT: i've edited the code, but still this give me the same problem :S

You have two problems here. The first is that if an exception is thrown during your write to the file, the output stream is not closed (same for the read):
try {
OutputStream someOutput = /* a new stream */;
/* write */
someOutput.close();
The second problem is that if there's an exception you aren't notified:
} catch (Exception e) {
if (e instanceof FileNotFoundException) {
/* do something */
}
/* else eat it */
}
So the problem is almost certainly that some other exception is being thrown and you don't know about it.
The 'correct' idiom to close a stream is the following:
OutputStream someOutput = null;
try {
someOutput = /* a new stream */;
/* write */
} catch (Exception e) {
/* and do something with ALL exceptions */
} finally {
if (someOutput != null) someOutput.close();
}
Or in Java 7 you can use try-with-resources.

Return in a 'finally' statement

I'm trying to read ObjectOutputStream from a file and convert it to an arraylist.
This whole thing is happening inside a method which should read the file and return the array list:
public static List<Building> readFromDatabase(){
String fileName="database.txt";
FileInputStream fileIStream=null;
ObjectInputStream in=null;
List<Building> buildingsArr=null;
try
{
fileIStream = new FileInputStream(fileName);
in = new ObjectInputStream(fileIStream);
buildingsArr=(ArrayList<Building>)in.readObject();
}
catch(IOException e)
{
e.printStackTrace();
}
catch(ClassNotFoundException e)
{
Console.printPrompt("ArrayList<Building> class not found.");
e.printStackTrace();
}
finally{
Console.printPrompt("Closing file...");
close(in);
close(fileIStream);
return buildingsArr;
}
}
Java tells me that this is dangerous.
What are the alternatives?
I can't put the return in the "try" block because it won't do it / it won't close files in the "finally" block.
I need to both make sure files will be closed, and return the array list I created as well.
Any ideas?

I can't put the return in the "try" block because it won't do it / it
won't close files in the "finally" block.
Wrong, finally block would still execute if you put return in try block. Thus you can return in your try block.
try
{
//your code
return buildingsArr;
}
catch(IOException e)
{
e.printStackTrace();
}
catch(ClassNotFoundException e)
{
Console.printPrompt("ArrayList<Building> class not found.");
e.printStackTrace();
}
finally{
Console.printPrompt("Closing file...");
close(in);
close(fileIStream);
}

I would suggest starting to use Java 7, and the try with resources clause. http://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html
Ex:
static String readFirstLineFromFile(String path) throws IOException {
try (BufferedReader br = new BufferedReader(new FileReader(path))) {
return br.readLine();
}
}

You must either throw an Exception or return a value:
All you need to prove this is comment out the return "File Not Found" after the finally block and see that it won't compile.
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
public class ReturnFinallyExample
{
public static void main(final String[] args)
{
returnFinally();
}
private static String returnFinally()
{
try
{
final File f = new File("that_does_not_exist!");
final FileInputStream fis = new FileInputStream(f);
return "File Found!";
}
catch (FileNotFoundException e)
{
e.printStackTrace();
}
finally
{
System.out.println("finally!");
}
return "File Not Found!";
}
}
You must have the return after the finally or you have to either:
declare the method to throws FileNotFoundExceptoin and re-throw the FileNotException out.
or
wrap the FileNotFoundException with throw new RuntimeException(e)

EOFException in Java Android? Help needed

I am trying to do some kind of serialization where I can directly read and write objects from file.
To start of I just tried to write a character to file and tried to read it. This keeps giving me EOF exception always.
I am trying it on a Android device. Here is my code:
public class TestAppActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
try {
WriteToFile();
Load();
} catch (Exception e) {
e.printStackTrace();
}
}
public void Load () throws IOException
{
InputStream fis;
ObjectInputStream in = null;
try {
fis = new FileInputStream(Environment.getExternalStorageDirectory() + "\\test2.ser");
in = new ObjectInputStream(fis);
char temp = in.readChar();
} catch (IOException e) {
e.printStackTrace();
} finally {
in.close();
}
}
public static void WriteToFile() throws Exception {
try {
OutputStream file = new FileOutputStream(Environment.getExternalStorageDirectory() + "\\test2.ser");
ObjectOutput output = new ObjectOutputStream(file);
try {
output.writeChar('c');
} finally {
output.close();
}
} catch (IOException ex) {
throw ex;
}catch (Exception ex) {
throw ex;
}
}
}

In this case, EOFException means there is no more data to be read, which (again in this case) can only mean that the file is empty.
Why are you using ObjectInput/OutputStreams but only writing chars? You'd be better off with DataInput/OutputStreams for that usage.
Also there is no point in catching exceptions only to rethrow them.
Also there is no point in reading a char from a file unless you are going to put it somewhere other than in a local variable that isn't even returned by the method.

I have imported this code in my sample project with following change.
i replaced "\\test2.ser"with "/test2.ser" and it worked. please try this.