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Thread: Confused on how to add data from a list into a HashMap

  1. #1
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    Default Confused on how to add data from a list into a HashMap

    I am being asked to do the following:
    where the keys are names of runners and the values are their times. The keys should be sorted at all times.

    This method should iterate over*runners, populating the maps*juniorResults,standardResults*and*seniorResul ts, with the correct names and times of runners.

    runners is an ArrayList that stores the information.

    I have managed to get working:

    for (Runner runner: runners)
    if(runners.contains("Junior")

    I am confused on how to get the names of the runners and the times from the ArrayList so I can populate each of the maps with the right key/value. I am using BlueJ.


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    Default Re: Confused on how to add data from a list into a HashMap

    Can you paste the code of your Runner class?

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    Default Re: Confused on how to add data from a list into a HashMap

    Of course. I just realized I am missing an import for the class but otherwise that's the whole Runner class.

    /**
     * Class Runner - Simulates a runner in a Marathon
     * 
     *
     */
    public class Runner implements Comparable<Runner>
    {
    /* static variables */
     
    // To be added by students in Question 3, part (i)(a) and part(iv)(a)
    private static int nextNumber = 1; //intializes nextNumber and sets it to 1
    /* instance variables */
     
       private int number;       // runner's number
       private String name;      // runner's name
       private String ageGroup;  // standard, junior or senior
       private int time;         // runner's marathon time in minutes
     
     
       /**
        * Default constructor for objects of class Runner
        */
       public Runner()
       {
          super();
          this.name = "";
          this.ageGroup = "standard";
          this.time = 0;
     
     
     
        // additional code to be added by students in Q3, part (i)(b)
         this.number = nextNumber; //sets the value of number to 1
        this.number = nextNumber++; //increases the total of number by the value of nextNumber 
     
     
     
     
     
     
     
       }
     
        /**
         * 
         */
        public int compareTo(Runner anotherRunner)
        {
          return this.getTime()-(anotherRunner.getTime()); // compares one Runner's time to anotherRunner's time
           }
     
    /* instance methods */
     
        //Only those accessor methods that you will need have been included
     
       /**
        * Returns the receiver's number
        */
       public int getNumber()
       {
          return this.number;
       }
     
     
       /**
        * Sets the receiver's name
        */
       public void setName(String name)
       {
          this.name = name;
       }
     
     
       /**
        * Returns the receiver's name
        */
       public String getName()
       {
          return this.name;
       }
     
     
       /**
        * Sets the receiver's ageGroup
        */
       public void setAgeGroup(String group)
       {
          this.ageGroup = group;
       }
     
       /**
        * Returns the receiver's ageGroup
        */
       public String getAgeGroup()
       {
          return this.ageGroup;
       }
     
     
       /**
        * Sets the receiver's time
        */
       public void setTime(int time)
       {
          this.time = time;
       }
     
     
       /**
        * Returns the receiver's time
        */
       public int getTime()
       {
          return this.time;
       }
     
    }

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    Default Re: Confused on how to add data from a list into a HashMap

    how to get the names of the runners and the times
    Are those values contained in the Runner objects? Does the Runner class have accessor methods for getting them?
    If the ArrayList contains Runner objects, get the objects from the array list and use the accessor methods to get the contents you are looking for.
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: Confused on how to add data from a list into a HashMap

    I believe the values are but the Maps will be created in another class MarathonAdmin and I have tried to use getTime() and getName(), but when I try using it to populate the Map, BlueJ says the methods are not known or declared. Unless I need to create a new Runner object within the method and use the accessors that way.

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    Default Re: Confused on how to add data from a list into a HashMap

    says the methods are not known or declare
    Please copy the full text of the error messages and paste it here.
    Also post the code where the errors happen.
    If you don't understand my answer, don't ignore it, ask a question.

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