Input in a txt file

[AARON22]

Hello i want to write in a txt file name "Dogs.txt" i have done this code but in my file i can't see my inputs!i see null!! any helps???

public class Items extends Pelatis{
    public String Id;
    public int Posotita;
    public String Perigrafi;
    public double Price;
    

    public void setId(String val){
        this.Id=val;
    }
    public String getId(){
        return Id;
    }
    public void setPosotita(int val){
        this.Posotita=val;
    }
    public int getPosotita(){
        return Posotita;
    }
    public void setPerigrafi(String val){
        this.Perigrafi=val;
    }
    public String getPerigrafi(){
        return Perigrafi;
    }
    public void setPrice(double val){
        this.Price=val;
    }
    public double getPrice(){
        return Price;
    }




     //me8odos morfopoihmenhs epistrofhs se String twn metavlhtwn ths klashs(stoixeiwn ma8hth)

    public String showDetails() {
        return ("Κωδικός : "+getId()+ "\n Διαθέσιμη Ποσότητα:"+ getPosotita()+ "\nΠεριγραφή: " + getPerigrafi() + "\nΤιμή: " + getPrice());
    }

    public int showChangeDetails() {
        String msg =
                String.format("Θέλετε να αλλάξετε την παρακάτω εγγραφή;\n" + showDetails());
        int yes_or_no = JOptionPane.showConfirmDialog(null, msg, "modify student", JOptionPane.YES_NO_OPTION);
        return yes_or_no;
    }


    //me8odos perasmatos timwn stis metavlhtes ths Items
        public void addStoixeia() {

            int numberformat = 0;
        int numberdigits = 0;

// read in user input
        JTextField id = new JTextField();
        JTextField posotita = new JTextField();
        JTextField price = new JTextField();
        JTextField perigrafi = new JTextField();

        final JComponent[] inputs = new JComponent[]{
            new JLabel("Κωδικός"),
            id,
            new JLabel("Διαθέσιμη Ποσότητα"),
            posotita,
            new JLabel("Τιμή"),
            price,
            new JLabel("Περιγραφή"),
            perigrafi
        };

        //elegxos pws kapoio apo ta plaisia den einai kena
        while (id.getText().equals("") || posotita.getText().equals("") || price.getText().equals("") ||
       perigrafi.getText().equals("") || numberformat == 1 || numberdigits == 1)
{


    try{
            JOptionPane.showMessageDialog(null, inputs, "ΚΑΤΑΧΩΡΗΣΗ", JOptionPane.PLAIN_MESSAGE);
            Id = id.getText();
            Posotita = Integer.parseInt(posotita.getText());
            Price = Double.parseDouble(price.getText());
             Perigrafi = perigrafi.getText();
            }
    catch(NumberFormatException nfe)
            {
                //Handle exception
            numberformat = 0;
            }
                  

            if (id.getText().equals("") || posotita.getText().equals("") || price.getText().equals("") || perigrafi.getText().equals("") || numberformat == 1) {
                JOptionPane.showMessageDialog(null, "Θα πρέπει να συμπληρώσετε όλα τα πεδία!", "Απέτυχε", JOptionPane.WARNING_MESSAGE);
            }          
           
        }
    }




      //synarthsh evreshs tou id sto arxeio
    public String[] findFullName(String filename, String Id) {

        String[] grammes = {"$%^&*", null, null, null};
        int x = 0;
        try {
            boolean check = false;
            // Open the file that is the first command line parameter
            FileInputStream fstream = new FileInputStream(filename);
            // Get the object of DataInputStream
            DataInputStream in = new DataInputStream(fstream);
            BufferedReader br = new BufferedReader(new InputStreamReader(in));
            String strLine;
            //Read File Line By Line
            while ((strLine = br.readLine()) != null) {
                //append(save) se arxeio txt
                String[] temp = null;
                //h sunarthsh delimeter spaei to string se 3 kommatia dinontas times ston pinaka temp[] me 3 theseis
                //se onoma, epwnumo kai se ena trito kommati (dieu8unsh#thlefwno mazi) pou omws de mas afora edw
                temp = lineDelimiter(strLine, 4, "#");
                //elegxei an to onomatepwnumo pou dwsame taytizetai me to onomatepwnumo ths ekastote grammhs
                //an nai tote oloklhrh h grammh pernietai ston pinaka grammes[]
                if (temp[0].equals(Id)) {
                    check = true;
                    grammes[x] = strLine;
                    x = x + 1;
                }
            }
            //close input stream
            in.close();
        } catch (Exception e) {//Catch exception if any
            System.err.println("Error: " + e.getMessage());
        }
        return grammes;
    }



   //epistrefei th String anaparastash twn metavlhtwn ths Studentz me thn pros8hkh twn diaxwristikwn "#"
    //wste na mporei na ginei metepeitai o diaxwrismos apo thn delimeter (xrhsimeyei sth apo8hkeysh se txt)
    public String toString() {
        return String.format(getId() + "#" + getPosotita() + "#" + getPrice() + "#" + getPerigrafi());
    }


    //pros8hkh(append) mias grammhs String se arxeio .txt me onoma filename
    public void write2Txt(String temp2, String filename) {
        try {

            boolean append = true;
            FileWriter fw = new FileWriter(filename, append);

            fw.write(temp2 + "\n");//appends the string to the file
            fw.close();
        } catch (IOException ioe) {
            String message1 =
                    String.format(ioe.getMessage());
            JOptionPane.showMessageDialog(null, message1, "file save error", JOptionPane.WARNING_MESSAGE);
        }
    }


  //tropopoihsh stoixeiwn mias grammhs enos arxxeiou filename pou periexei to zhtoumeno Id
    public void modifyItem(String filename, String Id) {

        try {
            boolean check = false;
            String tempid = null;//gia perasma sthn findname
            int change = 1;
            // Open the file that is the first
            // command line parameter
            FileInputStream fstream = new FileInputStream(filename);
            // Get the object of DataInputStream
            DataInputStream in = new DataInputStream(fstream);
            BufferedReader br = new BufferedReader(new InputStreamReader(in));
            String strLine;
            //Read File Line By Line
            while ((strLine = br.readLine()) != null) {
                //append(save) se arxeio txt
                // Print the content on the console
                String[] temp = null;
                temp = lineDelimiter(strLine, 4, "#");  // se posa strings tha spasei px 4 edw


                if (temp[0].equals(Id)) {
                    check = true;
                    Items itm = new Items();
                    itm.setId(temp[0]);
               itm.Posotita = Integer.parseInt(temp[1]);
               itm.Price = Double.parseDouble(temp[3]);
               itm.setPerigrafi(temp[2]);

                    change = itm.showChangeDetails();
                             if (change == 0) {
                        itm.addStoixeia();
                        strLine = itm.toString();

                        //pairnei to Id wste parakatw na elegksei an sto temp uparxei diplo-eggrafh
                        tempid = itm.getId();

                    }
                }
                Items eggrafhstoarxeio = new Items();
                eggrafhstoarxeio.write2Txt(strLine, "temp.txt");
                //dhmiourgia tou temp.txt me allagmenh thn mia grammh

            }
            //Close the input stream
            in.close();
            String result3[] = findFullName("temp.txt", tempid);
            if (result3[1] != null)//an dld uparxoun 2 akrivws idies egrafes
            {
                
                String msg =
                        String.format("Το προϊόν με κωδικο :"+" "+tempid+" "+" υπάρχει ήδη η ποσότητα άλλαξε"+" "+result3[1]);
                JOptionPane.showMessageDialog(null, msg, "Ο ΧΡΗΣΤΗΣ ΥΠΑΡΧΕΙ ΗΔΗ!", JOptionPane.ERROR_MESSAGE);
                File oldbackup = new File("temp.txt");
                oldbackup.delete();


            }
        } catch (Exception e) {//Catch exception if any
            //System.err.println("Error: " + e.getMessage());
            String message1 =
                    String.format(e.getMessage());
            JOptionPane.showMessageDialog(null, message1, "file not found", JOptionPane.WARNING_MESSAGE);
        }
    }
public String[] lineDelimiter(String str, int num, String symboldelimit) {
        //elegxetai posa stoixeia ehei to string analoga me to noumero num
        String[] tempstr = new String[num];
        /* delimiter-sumvolo diaxwrisths */
        String delimiter = symboldelimit;
        // se posa strings tha spasei px "num" edw
        tempstr = str.split(delimiter, num);
        //epistrefei ton pinaka me ta epimerous stoixeia (pinakas mege8ous num)
        return tempstr;
    }

}

and thin in main

if(inputs=="ΚΑΤΑΧΩΡΗΣ"){
                    
                    Items itm=new Items();
                    itm.addStoixeia();


                    String result2[] = itm.findFullName("Dogs.txt", itm.getId());

                     if (result2[0] == "$%^&*") {
                        itm.write2Txt(itm.toString(), "Dogs.txt");
                        String informationmessage2 =
                                String.format("Η εγγραφή σας ολοκληρώθηκε με επιτυχία");
                        JOptionPane.showMessageDialog(null, informationmessage2,"ΟΛΟΚΛΗΡΩΣΗ ΕΓΓΡΑΦΗΣ",JOptionPane.INFORMATION_MESSAGE);
break;
                     }
                     else
                     {
                     dog.write2Txt(dog.toString(), "Dogs.txt");
                          String informationmessage4 =
                                String.format("Η καταχώρησή σας υπαρχει ");
                        JOptionPane.showMessageDialog(null, informationmessage4,"ΟΛΟΚΛΗΡΩΣΗ ΚΑΤΑΧΩΡΗΣΗΣ",JOptionPane.INFORMATION_MESSAGE);
                        break;
                      }

                      }

[Norm]

i see null!

Are you sure the Strings you are writing to the file have values and are not null?

[AARON22]

thanks for your answer!!i have solve it!!!!now i have another probleb!!
I want to update an input i have done for example when i give an Id that is allready in my file i want to update Posotita(new + old )
here in my code i found the sting line i want to change, but i can update it whith my new data (newPosotita) Any helps??

if(inputs=="ΚΑΤΑΧΩΡΗΣΗ "){
Dogs dog=new Dogs();
dog.addStoixeia();
int tempPosotita=dog.getPosotita();//i posotita pou dinw

String result2[] = dog.findFullName("Dogss.txt", dog.getId());

if (result2[0] == "dog.getId()"){

String temp[] = null;
temp= dog.lineDelimiter(result2[0], 4, "#");
dog.setId(temp[0]);
dog.Posotita=Integer.parseInt(temp[1]);
dog.Price=Double.parseDouble(temp[2]);
dog.setPerigrafi(temp[3]);

temp[0] = dog.toString();
int tempoldPosotita =dog.getPosotita();
int newPosotita=tempoldPosotita+tempPosotita;//i allagmeni posotita
dog.setPosotita(newPosotita);

Dogs eggrafhstoarxeio = new Dogs();
eggrafhstoarxeio.write2Txt(temp[0], "temp.txt");
rename("temp.txt", "Dogss.txt");
String msg =
String.format("Η καταχώρησή σας ενημερώθηκε με επιτυχία");
JOptionPane.showMessageDialog(null, msg, "ΚΑΤΑΧΩΡΗΣΗ", JOptionPane.INFORMATION_MESSAGE);


}

[Norm]

Sorry, I don't understand your problem. Could you explain or show an example?
It sounds like a substring problem. Look at the String class. It has methods for replacing parts of a String with another String.

[AARON22]

I wan't to update an input in a txt file! for example i have this data in a txt file (Id=Dog,Posotita=1,Price=100,Perigrafi=good) and give thise data as an input(Id=Dog,Posotita=2,Price=100,Perigrafi=good) I want if Id is the same to update this line in my file like this Id=Dog,Posotita=3(1+2),Price=100,Summary=good

[Norm]

Did you look at the String class? It has methods for replacing parts of a String.

[AARON22]

i used a replace mathod and it works! But i want to replace the old line with the new in my file! Now i get the newline and the old!

String temp[] = null;
                temp= dog.lineDelimiter(result2[0], 4, "#");
                dog.setId(temp[0]);
                dog.Posotita=Integer.parseInt(temp[1]);
                dog.Price=Double.parseDouble(temp[2]);
                dog.setPerigrafi(temp[3]);
             
                temp[0] = dog.toString();
                int tempoldPosotita =dog.getPosotita();
                int newPosotita=tempoldPosotita+tempPosotita;
                 dog.setPosotita(newPosotita);
               String oldPosotita = Integer.toString(tempoldPosotita);
               String newfPosotita = Integer.toString(newPosotita);

                String newline=temp[0].replace(oldPosotita,newfPosotita);
                
                Dogs eggrafhstoarxeio = new Dogs();
                eggrafhstoarxeio.write2Txt(newline, "Dogss.txt");

[cultclassic]

In the write2Txt method you are appending to the file:

FileWriter fw = new FileWriter(filename, append);

So the replaced text gets added to the end of the file.
You should do what you did in the method

public String[] findFullName(String filename, String Id) {....

Open the file, read the contents line by line, and
if the Id matches in a line, do the replacement in that line,
and save all the lines back into the file.

[AARON22]

you mean sth like this??

the newvalue is the value that i take as an input i want to pass it through main if i can!!!

public void updateItem(String filename,String Id,int newvalue){
  //open the file,read line by line and find correct line  
    String[] grammes = {"$%^&*", null, null, null};
        int x = 0;
        try {
            boolean check = false;
            // Open the file that is the first command line parameter
            FileInputStream fstream = new FileInputStream(filename);
            // Get the object of DataInputStream
            DataInputStream in = new DataInputStream(fstream);
            BufferedReader br = new BufferedReader(new InputStreamReader(in));
            String strLine;
            //Read File Line By Line
            while ((strLine = br.readLine()) != null) {
                //append(save) se arxeio txt
                String[] temp = null;
                //h sunarthsh delimeter spaei to string se 3 kommatia dinontas times ston pinaka temp[] me 3 theseis
               
                temp = lineDelimiter(strLine, 4, "#");
                //elegxei an to ID pou dwsame taytizetai me to ID ths ekastote grammhs
                //an nai tote oloklhrh h grammh pernietai ston pinaka grammes[]
                if (temp[0].equals(Id)) {
                    check = true;
                    grammes[x] = strLine;
                    x = x + 1;
            
            
            Items itm = new Items();
             String newtemp[] = null;
                newtemp= lineDelimiter(grammes[x], 4, "#");
               
                itm.setId(newtemp[0]);
                itm.Posotita=Integer.parseInt(newtemp[1]);
                itm.Price=Double.parseDouble(newtemp[2]);
                itm.setPerigrafi(newtemp[3]);
                             
                
                
                grammes[x] = itm.toString();
                int tempoldPosotita =itm.Posotita;
                int newPosotita=tempoldPosotita+newvalue;//i allagmeni posotita
                 
               String oldPosotita = Integer.toString(tempoldPosotita);
               String newfPosotita = Integer.toString(newPosotita);

               grammes[x]=newtemp[0].replace(oldPosotita,newfPosotita);
                itm.write2Txt(grammes[x], filename);
          }
            }
            
            //close input stream
            in.close();
        } catch (Exception e) {//Catch exception if any
            System.err.println("Error: " + e.getMessage());
        }
           
           }

and this in main

itm.updateItem("Dogss.txt",itm.getId(),itm.getPoso tita());

nothing changed!!