如何從具有數組列表的類中調用方法到另一個類？

Question

我上Java的第一學期，需要幫助來調用從下面的VotingMachine類到Candidate類的方法。 投票機類正在正確編譯。 謝謝大家提供的任何幫助。

import java.util.ArrayList;

/**
 * These are the fields for the Voting Machine Class.
 */
public class VotingMachine
{
    private ArrayList<String> candidateList;

    /**
     * The following constructor will establish the Candidate List
     */
    public VotingMachine()
    {
        candidateList = new ArrayList<String>();
    }

    /**
     * This constructor will store the Candidates for the Candidate List   
     */
    public void setCandidateList()
    {
        candidateList.add("Darnell Woffard");
        candidateList.add("Barack Obama");
        candidateList.add("Hillary Clinton");
    }    

    /**
     * This method will display the entire Candidate List.
     */
    public void printCandidateInfo()
    {
        for (int index=0; index < candidateList.size(); index++)
        {
            System.out.println(candidateList.get(index));
        }
    }

    /**
     * Method to the number of Candidates in the CandidateList Arraylist.
     */
    public int getNumberofFiles()
    {
        return candidateList.size();       
    }

   /**
    * Method to select one candidate by first providing an index number.
    */
   public void listFile(int index)
   {
       if(index >= 0 && index < candidateList.size()){
           String filename = candidateList.get(index);
           System.out.println(filename);
       }
   }

    /**
     * This method will enable a user to remove a candidate.
     */
    public void removeFile(int index)
    {
        if(index >= 0 && index < candidateList.size()){
            candidateList.remove(index);
        }
    }

    /**
     * This method will add a file to the Candidate List.
     * 
     */
    public void addCandidate(String filename)
    {
       candidateList.add(filename);
    }


//----------
//The Candidate Class:

public class Candidate{

    private String name;
    private char party;
    private String candidateList;
// Add fields
    /**
     * Fields
     * name - Candidate's name, stored in a String
     * party - Candidate's political party, stored in a char
     * as 'r' for Republican, 'd' for Democrat, and 'i' for Independent
     */

    /**
     * Constructor
     * 
     * @param anyName - caller inputs Candidate name
     * @param anyParty - caller inputs Candidate's party affiliation
     * stored as a char
     * chars are assigned with single quotes.
     */
    public Candidate(String anyName, char anyParty)
    {
        name = anyName;
        party = anyParty;   
    }

    /**
     * The method will enable method calls from the Voting Machine Class.
     */
    public void main(String candidateList)
    {
        VotingMachine votingMachine = new VotingMachine();
    }

            /**
             * This method will define the candidates party affiliation.
             * public char setParty()
             */


//Complete the three methods and their comments.    
    /**
     * Method to retrieve the Candidate's name for the caller.
     * public String getName(String anyName)
     * 
     */



    /**
     * Method to retrieve the Candidate's party for the caller.
     * 
     * @return
     */



    /**
     * Method to change the Candidate's party
     * 
     * @param 
     */

Answer 1

實際上，我從中得到的是您正在嘗試制造投票機。 投票機是這里的主要班級，擁有不同候選人的信息。 因此，我們將在votingMachine類中成為候選人的對象。 注意：當我們應該創建一個Java項目時，請弄清它是什么主類和子類，這意味着哪個依賴於哪個。 在上面的示例中，類中存在關聯。 首先聲明一個ArrayList用於存儲候選類的對象。 如下所示。

private ArrayList<candidate> candidateList;

/**
 * The following constructor will establish the Candidate List
 */
public VotingMachine()
{
    candidateList = new ArrayList<String>();
}

現在為在ArrayList中添加新候選者，我將您的方法setCandidate()修改為

public void addNewCandidate(String name, char partySymbol)
{
    candidate candid = new candidate(name, partySymbol);// this will call the candidate constructor
    candidateList.add(candid);//add that object in ArrayList


}    

當ArrayList存儲對象的引用時，內置函數int get(int index)將返回對象的引用。 要打印該對象的信息或可以說出值，我們應該將一個函數定義為getName()和getParty() 。 而不是這個System.out.println(candidateList.get(index)); 您應該調用System.out.println(candidateList.get(index).getName()); 和System.out.println(candidateList.get(index).getParty()); 在以下方法中

public void printCandidateInfo()
{
    for (int index=0; index < candidateList.size(); index++)
    {
        System.out.println(candidateList.get(index));
    }
}

所以在候選類中定義函數為

public String getName()
{
    return name;

}

/**
 * Method to retrieve the Candidate's party for the caller.
 * 
 * @return
 */
public char getParty()
{
    return party;

}

以下方法將打印參考而不是候選者的信息，因此如上所述進行修改

public void listFile(int index)
{
      if(index >= 0 && index < candidateList.size()){
       String filename = candidateList.get(index);
       System.out.println(filename);
   }

}

當我修改它時，

import java.util.ArrayList;

/**
* These are the fields for the Voting Machine Class.
*/

public class VotingMachine
{
private ArrayList<Candidate> candidateList;

/**
 * The following constructor will establish the Candidate List
 */
public VotingMachine()
{
    candidateList = new ArrayList<>();
}

/**
 * This method will store the Candidates for the Candidate List   
 */
public void addNewCandidate(String name, char partySymbol)
{
    Candidate candid = new Candidate(name, partySymbol);// this will call the candidate constructor
    candidateList.add(candid);//add that object in ArrayList
}    

/**
 * This method will display the entire Candidate List.
 */
public void printCandidateInfo()
{
    for (int index=0; index < candidateList.size(); index++)
    {
        System.out.print(candidateList.get(index).getName());
        System.out.println("  " + candidateList.get(index).getParty());
    }
}

/**
 * Method to the number of Candidates in the CandidateList Arraylist.
 */
public int getNumberofFiles()
{
    return candidateList.size();       
}

/**
* Method to select one candidate by first providing an index number.
*/
public void listFile(int index)
{
   System.out.print(candidateList.get(index).getName());
   System.out.println("  " + candidateList.get(index).getParty());
}

/**
 * This method will enable a user to remove a candidate.
 */
public void removeFile(int index)
{
    if(index >= 0 && index < candidateList.size()){
        candidateList.remove(index);
    }
}

}

在候選類中，我剛剛添加了上面提到的getName()和getParty()方法。

問候