根据属性值从 ArrayList 中打印出选定的对象答案

【问题标题】：Printing out selected objects from ArrayList depending on attribute value根据属性值从 ArrayList 中打印出选定的对象
【发布时间】：2016-01-03 20:59:51
【问题描述】：

我有一种方法可以打印出运动员在比赛中的成绩。此方法打印出输入类别的最高分数。问题是它打印出每个运动员的每一个结果。我只希望它打印出每个运动员在输入类别中获得的最高值。我已经广泛搜索了答案，但以我有限的知识无法找到如何去做。所以我的问题是：如何只打印出 1 名运动员的最高值，以便获得真正的记分牌？

void typeOutHighScores() {
    ArrayList<Athlete> athletes= AthleteList.getArrayList();
Collections.sort(resultlist);
    String categoryToShow = null;
    System.out.println("Which category would you like to show highscores for?");
    categoryToShow = scanner.nextLine();
    categoryToShow = normalize(categoryToShow); //Just makes all letters small with first letter as capital.
    category matchedCategory= null;
    ArrayList<category> categories = CategoryList.getArrayList();
    for (int i = 0; i < categories.size(); i++) {
        category c = categories .get(i);
        if (c.categoryName().equals(categoryToShow)) {
            matchedCategory= c;
            break;
        }
    }
    if (matchedCategory== null) {
        System.out.println("Couldn't find " + categoryToShow + ".");
    } else {
        System.out.println("Resultatlist for " + categoryToShow + ": ");
        for (int i = 0; i < resultlist.size(); i++) {

            Athlete matched = null;
            int order = 0;
            Result res = resultlist.get(i);
            if (res.categoryName().equals(categoryToShow)) {
                for (int x = 0; x < athletes.size(); x++) {
                    Athlete del = athletes.get(x);
                    if (res.athleteStartNumber() == del.startNumber()) {
                        matched = del;
                        order = i + 1;
                        System.out.println(order + ". " + matched.surName() + " " + matched.lastName()
                                + " has the result: " + res.categoryValue());
                        break;
                    }
                }
            }
        }

    }
}

【问题讨论】：

标签： java if-statement for-loop arraylist

【解决方案1】：

考虑一下：

Map<Athlete,Double> athleteResults = new HashMap<Athlete,Double>();

而不是打印你所做的每个运动员

if(!athleteResults.containsKey(matched) //no score yet
  || athleteResult.get(matched) < res.categoryValue()) { //higher score
     athleteResult.put(matched, res.categoryValue());
}

然后迭代地图并打印结果。

祝你好运。

【讨论】：