[英]Collections.sort does not change list
I have a list of games that I wish to sort by the number of scores they have (in descending order).我有一个游戏列表,我希望按照它们的得分数量(按降序排列)进行排序。 I wrote this code for this purpose;
我为此目的编写了这段代码;
public void OnResponse(Object response) {
List<Game> games = (List<Game>)response;
Collections.sort(games, new Comparator<Game>() {
@Override
public int compare(Game o1, Game o2) {
if( o1.scores.size() > o2.scores.size()) {
return 1;
} else {
return 0;
}
}
});
trendingGames = games;
gridView = view.findViewById(R.id.trendingGrid);
gridView.setAdapter(new TrendingAdapter(games, getContext()));
view.findViewById(R.id.progressBar).setVisibility(View.GONE);
}
However, when I check the debugger I see that the list does not change at all.但是,当我检查调试器时,我发现列表根本没有改变。
You could use Integer#compare
to ease your life and make sure your Comparator
contract is respected您可以使用
Integer#compare
来简化您的生活并确保您的Comparator
合同得到尊重
@Override
public int compare(Game o1, Game o2) {
int score1 = o1.scores.size();
int score2 = o2.scores.size();
return Integer.compare(score1, score2);
}
This will work:这将起作用:
public class Game implements Comparable<Game> {
int score;
public Game(int score) {
this.score = score;
}
public int getScore() {
return score;
}
public void setScore(int score) {
this.score = score;
}
@Override
public int compareTo(Game anotherGame) {
return Integer.compare(this.score, anotherGame.getScore());
}
}
public static void main(String[] args) {
ArrayList<Game> games = new ArrayList<>();
games.add(new Game(5));
games.add(new Game(4));
games.add(new Game(1));
games.add(new Game(9));
Collections.sort(games);
Collections.reverse(games);
}
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