这个题目怎么做啊？急！ - 黑马程序员技术交流社区

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Scanner;
public class $ {
private static List<Person> data = new ArrayList<Person>();
public static void main(String... _) throws Exception {
Scanner in = null;
try {
in = new Scanner(new File("D:/a.txt"));
while (in.hasNextLine()) {
String str = in.nextLine();
String[] arr = str.split(" ");// 注意txt里面两列之间需有个空格
data.add(new Person(arr[0], toInt(arr[1])));
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} finally {
if (in != null) {
in.close();
}
}
System.out.println("pai xu qian:" + data);
Collections.sort(data, new Comparator<Person>() {
public int compare(Person o1, Person o2) {
// 按年龄升序
return o1.getAge() - o2.getAge();
// 按年龄降序
// return o2.getAge() - o1.getAge();
}
});
System.out.println("pai xu hou:" + data);
FileWriter fw = new FileWriter(new File("D:/b.txt"));
for (Person p : data) {
fw.write(p.getName() + " " + p.getAge() + "\r\n");
}
fw.flush();
fw.close();
System.out.println("已经保存到D:/b.txt");
}
private static int toInt(String str) {
try {
return Integer.parseInt(str);
} catch (Exception e) {
return 0;
}
}
}
class Person {
private String name;
private int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String toString() {
return "{" + name + "," + age + "}";
}
}

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