Question

我读了一个文件，其中每一行都是这样的： userName，age，award

我需要编写两种排序类型：by userName和by age。我对第一个问题没有任何问题，但我不知道在这样的例子中如何按年龄排序。我尝试在每行中使用年龄切换名称，但它不起作用。这就是我所拥有的（它基本上只是从文件中读取并显示它）：

try{
            File file=new File(path); 
            BufferedReader read=new BufferedReader(new FileReader(file));
            String line=read.readLine();
            all+=line+"\n";
            while(line!=null){
                line=save.readLine();
                all+=line+"\n";
            }

            String [] tabUsers=all.split("\n");       




            String display="";               
            for(int a=0;a<tabUsers.length-1;a++){        
                display+=tabUsers[a]+"\n";
            }

            for(int c=0;c<tabUsers.length-1;c++){
                    System.out.println(tabUsers[c]);

        }


        }
        catch(Exception ex){

        }

有什么想法吗？

我试过这个，但它不起作用：

  for(int b=0;b<tabUsers.length-1;b++){
               String eachLine =tabUsers[b];
                String [] splitLine=eachLine.split(",");
                splitLine[0]=splitLine[1];
            }

Answer 1

将您的数据读入这样的对象集合中：

public class User {
    final String name;
    final int age;
    final String award;

    public User(String name, int age, String award) {
        this.name = name;
        this.age = age;
        this.award = award;
    }
}

然后使用Collections.sort和Comparator<User>进行排序：

User bob = new User("Bob", 44, null);
User zack = new User("Zack", 13, null);
List<User> users = Arrays.asList(bob, zack);

//sort by age
Collections.sort(users, new Comparator<User>() {
    @Override
    public int compare(User user1, User user2) {
        return Integer.compare(user1.age, user2.age);
    }
});

//sort by name
Collections.sort(users, new Comparator<User>() {
    @Override
    public int compare(User user1, User user2) {
        return user1.name.compareTo(user2.name);
    }
});

Answer 2

首先从每一行获取名称和年龄。然后你可以将东西放在两个treeMaps上，一个是Names键，另一个是Age键。类似的东西：

    String[] lines = new String[3];
    lines[0] = "Michael 25 Award_1";
    lines[1] = "Ana 15 Award_2";
    lines[2] = "Bruno 50 Award_3";

    String[] parts;
    Map<String, String> linesByName = new TreeMap<String, String>();        
    Map<Integer, String> linesByAge = new TreeMap<Integer, String>();

    for (String line : lines) {
        parts = line.split(" ");
        linesByName.put(parts[0], line);
        linesByAge.put(Integer.parseInt(parts[1]), line);
    }

    System.out.println("Sorted by Name:");

    for (Map.Entry<String, String> entry : linesByName.entrySet()) {
        System.out.println(entry.getValue());
    }

    System.out.println("\nSorted by Age:");

    for (Map.Entry<Integer, String> entry : linesByAge.entrySet()) {
        System.out.println(entry.getValue());
    }

按索引java排序

2 个答案: