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Thread: Sorting a list error

  1. #1
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    Default Sorting a list error

    I am reading a file and sorting a list, and I cannot figure out why I am getting an error on line 15 that contains the following code
    	 Collections.sort(sortedContributorList, new Contributor());

    This is the error I keep getting:

    The method sort(List<T>, Comparator<? super T>) in the type Collections is not applicable for the arguments (LinkedList<Contributor>, Contributor)



    import java.util.*;
    import java.io.*;
     
     
    public class myhashTable {
     
     public static LinkedList<Contributor> sortedContributorList = new LinkedList<Contributor>();
     
    public myhashTable(){
     
    }
    public void sortedLL(){
    	readFile();
    	 Collections.sort(sortedContributorList, new Contributor());
    	 printSortedList(sortedContributorList);
    }
     
    private static void readFile()
    {//opens a private method for reading the contributor.csv file
    	String fileLocation ="C:address/here.csv";
     
            //variable to hold the file 
            String readLine;//sets the variable to read the lines within the file
            BufferedReader csvBuffReader;//calls the reader to read the text from a character-input stream
     
            try//
            {//opens a try condition. In this instance we are trying to read a file
                csvBuffReader = new BufferedReader (new FileReader(fileLocation));//creates a new reader for reading the .csv file
     
                while ((readLine = csvBuffReader.readLine()) != null)//creates a while loop and condition for reading the line
                {//opens the while loop... the condition states, while there are lines to read, keep reading them, when the line is empty, stop reading
                    Contributor contributors = createContribList(readLine);//creates a new linked list/stack to store the contents of the read file
     
                    addToList (contributors);//as the file is being read, this places the information into a linked stack
                }//closes the while loop
            }//ends the try condition
     
            catch (IOException e)//presents a solution for handling an error if the try was unable to import the file or export data to a file
            {//opens the catch block
                System.out.println(e.toString());//if an error occurs, the error handler would print an error message to screen
            }//ends the catch block
     
            System.out.println("Reading the CSV file was successful.");//prints message to the screen
    }//end
     
    public static Contributor createContribList (String line){
        final String LL = ", ";//sets the variable to read the line until a comma appears, then proceeds to call that string a token
        StringTokenizer lineToken;//breaks the lines of text into desired strings for enhanced readability
        int tokenNumber = 0;//sets and initializes the variable
        Contributor sortedList = new Contributor();//creates a new linked list/stack for storing information from the file
     
        lineToken = new StringTokenizer(line, LL);//creates a new tokenizer for breaking the lines of information into appropriate sections
     
                while(lineToken.hasMoreTokens()){ // while loop to set conditions to set data with tokennumber as long as it has more tokens
                    switch (tokenNumber){// sentinel switch to move tokenizer and set data in variables with data types
                        case 0: sortedList.setFirstName(lineToken.nextToken());
                                    break;
                        case 1: sortedList.setLastName(lineToken.nextToken());
                                    break;
                        case 2: sortedList.setCountry(lineToken.nextToken());
                                    break;
                        case 3: sortedList.setPhoneNumber(lineToken.nextToken());
                                    break;
                        case 4: sortedList.setContributorAmount(Double.valueOf(lineToken.nextToken()));
                                    break;
                        case 5: sortedList.setId(Integer.valueOf(lineToken.nextToken()));
                        break;
     
                    }//ends the switch condition for placing tokenized data into the appropriate sections
                    tokenNumber++;//Increments the token number so that each token is read
                }//ends the while loop
                return sortedList;//returns the tokenized and switched information 
            }//ends the private method for storing the switched and tokenized data read from a file
     
    public static void addToList(Contributor LL)//method to add data to LL
    {//opens the private method
      sortedContributorList.add(LL);//add the data into each node of the linked list/stack  
    }//closes the private method
     
        public static void printSortedList(List<Contributor> lL)//prints info in the linked list/stack
    {//opens the private method
        Contributor currentSort;//sets the variable for the linked list
        for (int count=0;count<lL.size(); count++)//creates a loop for reading the linked list/stack. once the stack is empty the compiler stops reading
        {//opens the for loop
            currentSort = lL.get(count);//get the information
            System.out.println("Contributor # " + (count+1));//header
            System.out.println();//formatting readability
            currentSort.printContr();// prints nodes
        }//ends the for loop
    }
     
    }


  2. #2
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    Default Re: Sorting a list error

    Well, look at the error message:
    The method sort(List<T>, Comparator<? super T>) in the type Collections is not applicable for the arguments (LinkedList<Contributor>, Contributor)
    it is pretty straight forward.

    The "sort" method needs a List as first parameter and a Comparator as a second parameter.
    You try to give it a List and a Contributor. I dont know what a Contributor is supposed to be but it is obviously not a Comparator.

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    Default Re: Sorting a list error

    Welcome to the Forum! Thanks for taking the time to learn to post code correctly, and if you haven't already, please read this topic to see other useful info for newcomers.

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