java - firebase 数据库到自定义 ListView 问题

Question

如果我做对了，有人能看到吗？从 firebase 数据库我正在使用这个获取我的数据

        FirebaseDatabase database = FirebaseDatabase.getInstance();
        database.getReference()
                .child("Users").child("Displayname")
                .addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(DataSnapshot dataSnapshot) {
                        for (DataSnapshot snapshot : dataSnapshot.getChildren()){
  Map<String, Object> map =(Map<String, Object>) snapshot.getValue();
                            for (Map.Entry<String, Object> entry : map.entrySet()){

                                Cred = (String) entry.getValue();
                                friend = snapshot.getKey();
     @Override
                    public void onCancelled(DatabaseError databaseError) {

                    }
                });

并使用这个放置到字符串数组中

 List<String> list = new ArrayList<String>();
                                list.add(Cred+" "+friend);
                                String[] stringArray = list.toArray(new String[0]);

通过使用下面的代码，我想将它降序排列

 Comparator comparator = new Comparator<String>() {
                                    @Override
                                    public int compare(String o1, String o2) {
                                        String num1 = o1.split(" ")[0];
                                        String num2 = o2.split(" ")[0];
                                        return Integer.parseInt(num2) - Integer.parseInt(num1);
                                    }
                                };
                                Arrays.sort(stringArray, comparator);
                                System.out.println(Arrays.toString(stringArray));

但我没有得到我的结果:

Expected result : 

"300.0 Baul",
"4.0 Alex",
"1.0 Lex B05"

My system print out:

2019-12-23 15:17:02.285 752-752/com.seamans.marina I/System.out: [4.0 Alex]
2019-12-23 15:17:02.292 752-752/com.seamans.marina I/System.out: [300.0 Baul]
2019-12-23 15:17:02.296 752-752/com.seamans.marina I/System.out: [1.0 Lex B05]

我的 firebase 数据库:

Answer 1

尝试用这种方式排序

Collections.sort(stringArray, (c1, c2) -> {
    String num1 = c1.split(" ")[0];
    String num2 = c2.split(" ")[0];
    return Double.compare(Double.parseDouble(num2), Double.parseDouble(num1));
});
System.out.println(stringArray);

更新 1:用上面的内容替换此 block

 Comparator comparator = new Comparator<String>() {
                                    @Override
                                    public int compare(String o1, String o2) {
                                        String num1 = o1.split(" ")[0];
                                        String num2 = o2.split(" ")[0];
                                        return Integer.parseInt(num2) - Integer.parseInt(num1);
                                    }
                                };
                                Arrays.sort(stringArray, comparator);
                                System.out.println(Arrays.toString(stringArray));