deleting record

[Abhradeep Banerjee]

have pasted part of my code for delete
im not sure how to delete a record from linklist

all i know that i have to do a LL.remove();
not sure what to put in the brackets
i also want to put a index number next to each record when it displays
and when the user enters that number the program deletes the record

  if (line.equals("1")) {
                        for (int i = 0; i < LL.size(); i++) {
                            System.out.println(LL.get(i));
                            System.out.println(i);

                        }

                        System.out.println(Delete_Record);



                        BufferedReader delete = new BufferedReader(new InputStreamReader(System.in));
                        line = delete.readLine();


                        FileWriter fwp = new FileWriter(inFile);
                        BufferedWriter bwp = new BufferedWriter(fwp);
                        PrintWriter outFile = new PrintWriter(bwp);


                        StringTokenizer tokenizer = new StringTokenizer(line, "|");
                        index = Integer.parseInt(tokenizer.nextToken());
                        NRIC = tokenizer.nextToken();
                        Name = tokenizer.nextToken();
                        srcCountry = tokenizer.nextToken();
                        deptDate = tokenizer.nextToken();
                        deptTime = tokenizer.nextToken();
                        destCountry = tokenizer.nextToken();
                        arrDate = tokenizer.nextToken();
                        arrTime = tokenizer.nextToken();

                        //create new Travel object
                        Travel rr = new Travel(index, NRIC, Name, srcCountry, deptDate, deptTime, destCountry, arrDate, arrTime);

                        //remove this item object to Llist
                        

                        for (int i = 0; i < LL.size(); i++) {
                            outFile.println(LL.get(i));
                            LL.remove(LL.get(i).index);
                        }

                        outFile.close();

  

Thanks

[Campbell Ritchie]

Why are you using a LinkedList rather than an ArrayList which allows random access?

[subhash kumar]

  
                LinkedList<String> ll = new LinkedList<String>();
		ll.add("a");
		ll.add("b");
		ll.add("c");
		ll.add("d");
		System.out.println("before"+ll);
		for (Iterator iterator = ll.iterator(); iterator.hasNext();) {
			String string = (String) iterator.next();
			iterator.remove();
		}
		System.out.println("after"+ll); 

[Abhradeep Banerjee]

mine doesn't really work like that mine is in a text file
ill paste the whole code

  
import java.io.*;
import java.util.*;

public class lab6Ex1 {

    public static void main(String[] args) {


        //declare variables FileReader, bufferedReader & inFile and line
        FileReader fr = null;
        BufferedReader br = null;
        String inFile = "Travel_Records.txt";
        String line = "";


        //declare variables for Menus Input_prompt, IC_Prompt,etc
        final String INPUT_PROMPT1 = "\nPlease select one of the following options: \n"
                + "1)   Search flights by IC number \n"
                + "2)   Search flights by departure date \n"
                + "3)   Display all flights \n"
                + "4)   Insert new record or remove old record \n"
                + "5)   Exit program ";

        final String IC_PROMPT = "\n\n\nPlease enter the IC number";
        final String Dept_PROMPT = "\n\n\nPlease enter the departure date in the following format" + "dd/mm/yyyy";
        final String Insert_Remove_PROMPT = "\n\n\n \n"
                + "1) Remove Record\n"
                + "2) Insert Record\n"
                + "3) Return to previous menu\n"
                + "4) Exit Program";

        final String Insert_Record = "Please enter new record in the following format: Serial Number|SXXXXXXXG|Name"
                + " | Country |MM/DD/YYYY | Time in 24 hr clock | Country | MM/DD/YYYY | Time in 24 hr clock";
        final String Delete_Record = "Please enter the serial number of the record to delete";
        //declare var to contain the record files

        int index;
        String NRIC;
        String Name;
        String srcCountry;
        String deptDate;
        String deptTime;
        String destCountry;
        String arrDate;
        String arrTime;


        //declare and initiate new linked list

        LinkedList<Travel> LL = new LinkedList<Travel>();

        try {

            //initiate filereader and bufferedreader objects

            fr = new FileReader(inFile);
            br = new BufferedReader(fr);


            // while line is not null
            while ((line = br.readLine()) != null) {

                StringTokenizer tokenizer = new StringTokenizer(line, "|");
                index = Integer.parseInt(tokenizer.nextToken());
                NRIC = tokenizer.nextToken();
                Name = tokenizer.nextToken();
                srcCountry = tokenizer.nextToken();
                deptDate = tokenizer.nextToken();
                deptTime = tokenizer.nextToken();
                destCountry = tokenizer.nextToken();
                arrDate = tokenizer.nextToken();
                arrTime = tokenizer.nextToken();
                //create new Travel object
                Travel travel = new Travel(index, NRIC, Name, srcCountry, deptDate, deptTime, destCountry, arrDate, arrTime);
                //add this item object to Llist
                LL.add(travel);
                line = br.readLine();

            }
            //close buffered reader
            br.close();
        } catch (FileNotFoundException e) {
            System.out.println("The file" + inFile + "was not found");
        } catch (IOException e) {
            System.out.println("Reading error");
        } finally {
            //close filereader
            if (fr != null) {
                try {
                    fr.close();
                } catch (IOException e) {
                    System.out.println("error closing file");
                }

            }

        }
        //create readers to read from user input
        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
            System.out.println(INPUT_PROMPT1);
            //read one line from user
            line = reader.readLine();

            while (!line.equals("0")) {


                //read one line from user
                Collections.sort(LL);

                if (line.equals("1")) {
                    System.out.println(IC_PROMPT);

                    BufferedReader IC = new BufferedReader(new InputStreamReader(System.in));
                    line = IC.readLine();
                    for (int n = 0; n < LL.size(); n++) {

                        if (LL.get(n).NRIC.toUpperCase().contains(line.toUpperCase())) {

                            //printout information of the video
                            System.out.println(LL.get(n));

                        }

                    }

                } else if (line.equals("2")) {

                    System.out.println(Dept_PROMPT);
                    BufferedReader Dept = new BufferedReader(new InputStreamReader(System.in));
                    line = Dept.readLine();
                    for (int n = 0; n < LL.size(); n++) {

                        if (LL.get(n).deptDate.toUpperCase().contains(line.toUpperCase())) {

                            //printout information of the video
                            System.out.println(LL.get(n));
                        }
                    }
                } else if (line.equals("3")) {
                    for (int n = 0; n < LL.size(); n++) {
                        System.out.println(LL.get(n));
                    }

                } else if (line.equals("4")) {
                    System.out.println(Insert_Remove_PROMPT);
                    BufferedReader Insert = new BufferedReader(new InputStreamReader(System.in));
                    line = Insert.readLine();



                    if (line.equals("1")) {
                        for (int i = 0; i < LL.size(); i++) {
                            System.out.println(LL.get(i));
                            System.out.println(i);

                        }

                        System.out.println(Delete_Record);



                        BufferedReader delete = new BufferedReader(new InputStreamReader(System.in));
                        line = delete.readLine();


                        FileWriter fwp = new FileWriter(inFile);
                        BufferedWriter bwp = new BufferedWriter(fwp);
                        PrintWriter outFile = new PrintWriter(bwp);


                        StringTokenizer tokenizer = new StringTokenizer(line, "|");
                        index = Integer.parseInt(tokenizer.nextToken());
                        NRIC = tokenizer.nextToken();
                        Name = tokenizer.nextToken();
                        srcCountry = tokenizer.nextToken();
                        deptDate = tokenizer.nextToken();
                        deptTime = tokenizer.nextToken();
                        destCountry = tokenizer.nextToken();
                        arrDate = tokenizer.nextToken();
                        arrTime = tokenizer.nextToken();

                        //create new Travel object
                        Travel rr = new Travel(index, NRIC, Name, srcCountry, deptDate, deptTime, destCountry, arrDate, arrTime);

                        //remove this item object to Llist
                        

                        for (int i = 0; i < LL.size(); i++) {
                            outFile.println(LL.get(i));
                            LL.remove(LL.get(i).index);
                        }

                        outFile.close();




                    } else if (line.equals("2")) {
                        System.out.println(Insert_Record);
                        BufferedReader insert = new BufferedReader(new InputStreamReader(System.in));
                        line = insert.readLine();


                        FileWriter fwp = new FileWriter(inFile);
                        BufferedWriter bwp = new BufferedWriter(fwp);
                        PrintWriter outFile = new PrintWriter(bwp);


                        StringTokenizer tokenizer = new StringTokenizer(line, "|");
                        index = Integer.parseInt(tokenizer.nextToken());
                        NRIC = tokenizer.nextToken();
                        Name = tokenizer.nextToken();
                        srcCountry = tokenizer.nextToken();
                        deptDate = tokenizer.nextToken();
                        deptTime = tokenizer.nextToken();
                        destCountry = tokenizer.nextToken();
                        arrDate = tokenizer.nextToken();
                        arrTime = tokenizer.nextToken();

                        //create new Travel object
                        Travel travel = new Travel(index, NRIC, Name, srcCountry, deptDate, deptTime, destCountry, arrDate, arrTime);

                        //add this item object to Llist
                        LL.add(travel);

                        for (int i = 0; i < LL.size(); i++) {
                            outFile.println(LL.get(i));
                        }

                        outFile.close();



                    } else if (line.equals("3")) {
                    } else if (line.equals("4")) {

                        System.out.println("Are you sure you want to exit? Y/N");
                        BufferedReader exit = new BufferedReader(new InputStreamReader(System.in));
                        line = exit.readLine();
                        if (line.equalsIgnoreCase("Y")) {
                            System.exit(0);
                        }
                    }

                } else if (line.equals("5")) {
                    System.out.println("Are you sure you want to exit? Y/N");
                    BufferedReader exit = new BufferedReader(new InputStreamReader(System.in));
                    line = exit.readLine();
                    if (line.equalsIgnoreCase("Y")) {
                        System.exit(0);

                    } else {
                        System.out.println("Wrong entry");

                    }
                } else {
                    System.out.println("Wrong Entry");
                }
                System.out.println(INPUT_PROMPT1);
                line = reader.readLine();
            }
        } catch (IOException e) {
            System.out.println("error");
        }
    }
}
   

thanks