Question

我是Java和Android开发领域的法国初学者。其实我尝试练习，但是我被困住了...

我有一个对象（播放器）的ArrayList（playersList2），播放器包含字符串（mFirstName）和int（mScore））

我尝试了收集，循环，并且阅读了许多文档和论坛，但是我找不到解决方案，但是我敢肯定这很容易

    Players players = new Players(mFirstname, mScore);

    mPreferences = getSharedPreferences(PREF_PLAYERS_LIST, MODE_PRIVATE);
    String fromJsonPlayersList = mPreferences.getString(PREF_PLAYERS_LIST, null);

    Gson gson = new Gson();
    ArrayList<Players> playersList2 = gson.fromJson(fromJsonPlayersList, new TypeToken<ArrayList<Players>>()
    {
    }.getType());

    /* find the weakiest players/

    if  //mscore is bigger than weakest players
    {//remove the weakest players and add this one
    }*/

我想在整个ArrayList中找到最小的mScore来创建条件（如果当前的mScore>最小的playersList2用当前的Players替换最弱的PlayersList2的球员）

非常感谢

Answer 1

假设这是您的Players课：

    public class Players {
    String mFirstName;
    int mScore;

    public Players(String mFirstName, int mScore){
        this.mFirstName = mFirstName;
        this.mScore = mScore;
    }
}

这将获得最低分：

public static void main(String[] args) {

    ArrayList<Players> playersList2 = new ArrayList<>();

    for (int i = 0; i < 10; i++){
        Players player = new Players("name", i);
    }

    Players lowestScore = playersList2.get(0);

    for (Players p: playersList2) {
        if (p.mScore < lowestScore.mScore){
            lowestScore = p;
        }
    }

    System.out.println(lowestScore.mScore);
}

Answer 2

最简单的解决方案是使用简单的for循环，例如：

Players minScorePlayer = playersList2.get(0);
for (Players player: playersList2) {
   if (player.getScore() < minScorePlayer.getScore()) {
      minScorePlayer = player;
   }
}
//now minScorePlayer variable contains the reference to a player with the minimal score

P.S。该代码旨在为您提供总体思路。您可能需要根据需要进行调整。

Answer 3

有多种方法可以做到这一点。

在开始解决方案之前，让我们在这里有Player类：

class Player {
    String firstName;
    int score;

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public int getScore() {
        return score;
    }

    public void setScore(int score) {
        this.score = score;
    }
}

一种方法是循环访问ArrayList并找到得分最低的播放器，另一种方法是使用Stream API查找得分最低的播放器。

解决方案1：在这里，我们遍历列表以查找得分最低的玩家。

List<Player> players = new ArrayList<>();

// .. add some players in the List players

Player weakestPlayer = null;
int minScore = Integer.MAX_VALUE;
for(Player player : players) {
    if(player.getScore() < minScore) {
        weakestPlayer = player;
    }
}

解决方案2：在Java中使用Stream API是一个有点复杂的解决方案。

Player weakestPlayer = players
        .stream()
        .min(Comparator.comparing(Player::getScore))
        .orElseThrow(NoSuchElementException::new);

此解决方案使用Java Stream API查找得分最低的播放器。在这里，我们使用min（）方法来找到得分最低的玩家。 min（）方法需要一个比较器，该比较器将帮助它比较分数并确定哪个球员的分数最低。下面的代码行为int获取比较器。

Comparator.comparing(Player::getScore)

如果列表为空，则将找不到一个得分最低的球员，这将引发错误。

在ArraysList对象中查找最小值

3 个答案: