Creating file on a certain folder based on input

[drcipres perez]

Hello.

I have a series of classes that take 3 files as input, and create 3 files as output, the problem is that these 3 output files are not being created. I want them to be created on the same folder as the .java and .class files. These are the 2 things that I tried:

	String dir = System.getProperty("user.dir");
    File ficheromapa = new File(dir, args[5]); 
	try {
	ficheromapa.createNewFile();}catch (IOException e) {} //CREATES FILE
	PrintWriter pw = new PrintWriter(ficheromapa); //WRITES FILE

This piece of code works if I compile the .java files as a package, meaning that inside of my folder, I create another folder with the .class files in there (by doing "javac -d .")

But this is not what Im looking for, so I also tried:

File ficheromapa = new File("/home/eetlabs.local/pii/pii212/Practicas/P6b/+args[5]);

instead of the previous File line. And this one still doesn't work. The output should be something like "file4.txt" and I want to create a file called file4.txt inside the folder P6b, and I dont get why none of these two options work.

EDIT: The full code:

package P6b;

import java.util.Scanner; 
import java.io.File;
import java.io.PrintWriter;
import java.io.FileNotFoundException;
import java.io.IOException;

public class P6b {
    
    private static Parking miParking;
    private static CarDB cdb = new CarDB(); //SE CREA EL OBJETO CDB MEDIANTE EL CONSTRUCTOR VACÍO IMPLÍCITO
    
    public static void main (String[] args) throws FileNotFoundException {
	String dir = System.getProperty("user.dir"); //IMPRIME C:\Users\JuanC\practicas\practica6b
	miParking = new Parking(args[0]); //CREA EL PARKING CON EL CONSTRUCTOR //DEBE SER VARIABLE GLOBAL

	cdb.readCityCarsFile(args[3]); //SE LLAMA AL MÉTODO SOBRE EL OBJETO CDB, QUE ACTUALIZARÁ EL VALOR DEL ATRIBUTO CITYCARS[]
			   
	new P6b().processIO(args[1]); //SE ACTUALIZA EL PARKING CON ENTRADAS Y SALIDAS
	miParking.saveParking(args[2]); //SE ALMACENA EL PARKING CREADO EN EL TERCER FICHERO

	cdb.sortByPlate();
	
	cdb.saveCarsToFile(args[4]); //SE LLAMA AL MÉTODO SOBRE EL OBJETO CDB, QUE GUARDARÁ LA ARRAYLIST DE COCHES EN EL FICHERO

	String mapa = miParking.toMap();
	File ficheromapa = new File(dir, args[5]);
	try {
	ficheromapa.createNewFile();}catch (IOException e) {}
	PrintWriter pw = new PrintWriter(ficheromapa);
	pw.println(mapa);
	pw.close();

	System.out.println("Total power = " + cdb.computeTotalPower());
	System.out.println("Median Battery Charge Level = " + cdb.computeAverageBatteryLevel());

    }

    private void processIO(String filename) throws FileNotFoundException{
        
	File file2 = new File(filename);
	Scanner inputfichero = new Scanner(file2);
	
	while (inputfichero.hasNext() == true) { //SE LEE EL FICHERO, OBSERVANDO SI CADA LINEA DEL FICHERO ES UN COCHE QUE ENTRA O QUE SALE DEL PARKING
	    String linea = inputfichero.nextLine();
	    if (linea.startsWith("#")) {continue;}
	    else {
		String[] infocar = linea.split(";"); //SE DIVIDEN LAS LÍNEAS DEL SEGUNDO FICHERO
		if (infocar[0].equals("I") == true) { //SE COMPRUEBA SI LA LÍNEA QUE SE ESTÁ LEYENDO ES UN COCHE QUE ENTRA O QUE SALE DEL PARKING
		    Car carIO = cdb.getCarFromPlate(infocar[1]);
		    miParking.carEntry(carIO, infocar[2]); //SE INVOCA AL MÉTODO CARENTRY O CARDEPARTURE EN FUNCIÓN DE SI ENTRAN O SALEN LOS COCHES  
		} else {
		    if (cdb.getCarFromPlate(infocar[1]) instanceof CombustionCar) {
			miParking.carDeparture(infocar[1]);}
		    else {
			cdb.increaseCarBatteryChargeLevel(infocar[1], infocar[2], miParking.carDeparture(infocar[1]));
			miParking.carDeparture(infocar[1]);}
		}
	    }
	}
	inputfichero.close(); //SE CIERRA EL FICHERO
	
    }
    
}

[Campbell Ritchie]

Please always indent your code correctly and space it out; what you showed is very difficult to read. If I find it difficult to read, you will find it much harder.
How are you closing your print writer? You didn't show us that. If you fail to close it, there is a risk of the files not being written.

drcipres perez wrote:. . .

File ficheromapa = new File("/home/eetlabs.local/pii/pii212/Practicas/P6b/+args[5]);

. . .

Please always post exactly the same code as you are using; what you showed won't compile.
Stop using File; it is regarded as legacy code. More details in the Java™ Tutorials.

Why are you using so many command‑line arguments? Why have you got so much code in the main() method? Why are you keeping your work files and the code in the same directory? I don't like any of those last three things.

[Tim Holloway]

Caution: people who code empty catch clauses risk physical assault. ALWAYS do something in your catch clause, even if it's only a printStackTrace()! Never silently eat exceptions or you'll end up not knowing what happened. And if you come for help from me, neither will I, which is where the risk of assault comes from.

Also, "if (xyz == true)" in Java is a sign of ignorance. Since xyz has to be boolean, the comparison is redundant. Just say "if (xyz) {..."

[Campbell Ritchie]

Please avoid editing your posts after they have been replied to; in this case it does no harm, so I shall let the changes stand. You have added the whole code to your original post.
Please beware of comments; a comment should always clarify things, but some, e.g.//SE CREA EL OBJETO CDB MEDIANTE EL CONSTRUCTOR VACÍO IMPLÍCITO...add nothing new. Please don't write ALL UPPER CASE. That comment does raise a question: why have you not written a constructor for that class? I don't like default constructors.
Some other comments, e.g. PrintWriter pw = new PrintWriter(ficheromapa); //WRITES FILE...are incorrect. That doesn't write anything to the file. You appear to be opening the print writer and closing it before using it. Anyway, that isn't the correct way to close your writer. Look in the Java™ Tutorials.

try (Formatter f =
      new Formatter(
            "/home/campbell/Documents/pii/pii212/Practicas/P6b/" +
            args[5], "UTF-8"))
/* Alternative to line 4: fileName, "UTF-8)) */
{
   while (something)
   {
      f.format("...%n", someObjectToWrite);
   }
}
catch (FileNotFoundException ex)
{
   // exception handling
}

You can wrap that sort of code in a loop, but it really merits a method to itself, in which case I would allow the exception to propagate by deleting the catch and declaring that the method throws FileNotFoundException.

boolean needsWriting = true;
do
{
   try
   {
      writeToFile(fileName);
      /* Following line only executed if writing successful */
      needsWriting = false;
   }
   catch (FileNotFoundException ex)
   {
      /*
       * Handle exception. Options: enter new file name and allow
       * loop to run again. Miss out new file name and allow
       * needsWriting to become false. Or other actions.
       */
   }
} while (needsWriting);

It might be worth finding out how to use a JFileChooser to choose the files.
I think you should move reading and writing the files into different methods. Your file reading can be called from a constructor, but methods called from a constructor should have private access or be marked final. (It is not necessary for a method to be both final and private.) Again don't call close() on a Scanner, but use try with resources instead.
I don't like nextLine() on Scanners; it is better if at all possible to divide the line into parts and read the individual parts with next(), nextInt(), nextBigDecimal(), etc.
Don't write == true or == false. Both are poor style and error‑prone because you might write = by mistake.
Never while (b == true) ... please.
Always while (b) ... please.
Never while (b == false) ... please.
Always while (!b) ... please.

[edit] Sorry I was mistaken; you do appear to be writing something in that file. I have struck out the line where I was mistaken above. The line l5 I mentioned doesn't write anything to the file. It might create the file, but any writing occurs later.