为随机枚举对象分配概率 [英] Assigning probability to a random enum object

问题描述

所以我有一个枚举：

public enum Party {

    DEMOCRAT, INDEPENDENT, REPUBLICAN
}

我目前有三个类之一：

public class ElectoralCollege {
    public static final String FILE = "Electoral201X.txt";
    private ArrayList <State> stateVotes;
    Random rand = new Random();

    public ElectoralCollege() throws IOException    {

        stateVotes = new ArrayList<State>();
        assignStates();
    }

    public void assignStates() throws IOException   {

        File f = new File(FILE);
        Scanner fReader = new Scanner(f);

        while(fReader.hasNext())    {

            String stateData = fReader.nextLine();
            int stateEnd = stateData.indexOf(" - ");
            String stateName = stateData.substring(0, stateEnd);
            String stateVotes = stateData.substring(stateEnd + 2);
            //System.out.println(stateName + " " + stateVotes);


        }

这里我正在从一个文件有州名称和选举人数如下：佛罗里达州 - 29，所以这些都是想出来的。

Here I am reading from a file that has state names and their number of electoral votes as follows "Florida - 29", so that's all figured out.

接下来我要做的是使用随机对象从我们党的枚举中指定一个派对。共和党和民主党必须有2/5的获胜机会，而独立必须有1/5的机会。然后我必须创建一个State对象（将状态名称，投票数和派对作为参数），并将其抛入该数组列表中。最有可能为每个循环使用一个循环，只需要做一些更多的研究。

What I have to do next is use a random object to assign a party to them from my Party enum. Republican and Democrat must have a 2/5 chance of winning...while Independent must have a 1/5 chance. Then I must create a State object (which takes the state name, number of votes, and the party in as parameters) and toss it into that arraylist. Most likely going to use a for each loop for that, just need to do some more research on that.

我的问题是如何使用这个随机对象rand设定这三方的概率，并执行吗？任何人都有任何想法？

My question is how do I use this random object rand with a set probability for those three parties, and execute it? Anyone got any ideas?

编辑：底线是：如何为这三方实施2/5和1/5的概率，然后调用随机反对我根据这些概率给我一个派对？

Bottom line is: How do I implement a 2/5 and a 1/5 probability for those three Parties, and then call the random object to give me a party based on those probabilities?

在我的答案之后，我做到了：

AFTER mre's Answer, I did this:

Random rand = new Random();
    List<Party> parties = Arrays.asList(Party.DEMOCRAT, Party.DEMOCRAT, Party.REPUBLICAN, Party.REPUBLICAN, Party.INDEPENDENT);

稍后在....

public void assignStates（）throws IOException {

public void assignStates() throws IOException {

File f = new File(FILE);
Scanner fReader = new Scanner(f);

while(fReader.hasNext())    {

    String stateData = fReader.nextLine();
    int stateEnd = stateData.indexOf(" - ");
    String stateName = stateData.substring(0, stateEnd);
    String numVote = stateData.substring(stateEnd + 2);

    Party winner = parties.get(rand.nextInt(5));
    //System.out.println(stateName + " " + numVote + " " + winner);

    State voteInfo = new State(stateName, Integer.parseInt(numVote.trim()), winner);
    stateVotes.add(voteInfo);

}

}

已回答，新问题：使用foreach循环从数组列表中添加值，然后使用访问器打印它们

推荐答案

拥有5个派对实例的集合，其中2个为 DEMOCRAT ，2为 REPUBLICAN ，1是 INDEPENDENT ，然后使用随机数生成器生成随机索引（即0-4）用于访问例如

have a collection of 5 Party instances, where 2 are DEMOCRAT, 2 are REPUBLICAN, and 1 is an INDEPENDENT, and then use the random number generator to generate a random index (i.e. 0-4) for accessing e.g.,

import java.util.Arrays;
import java.util.List;
import java.util.Random;

public class Demo 
{
    public static void main(String[] args) 
    {
       Random r = new Random();
       List<Party> parties = Arrays.asList(Party.DEMOCRAT, Party.DEMOCRAT, Party.REPUBLICAN, Party.REPUBLICAN, Party.INDEPENDENT);

       System.out.println(parties.get(r.nextInt(parties.size())));
    }

    enum Party
    {
        DEMOCRAT,
        REPUBLICAN,
        INDEPENDENT;
    }
}

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