import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.util.*;/*** IO流读取文件用户信息根据年龄排序后，写到文件*/
public class Operate1 {public static void main(String[] args) throws Exception {BufferedReader reader = new BufferedReader(new FileReader("operate/src/operate418/silence/user.txt"));String line;TreeMap<Integer, String> treeMap = new TreeMap<>(new Comparator<Integer>() {@Overridepublic int compare(Integer age1, Integer age2) {int result = age1 - age2;result = result == 0 ? -1 : result;return result;}});while ((line = reader.readLine()) != null && !"".equals(line)) {if (line.contains("--")) {break;}String[] split = line.split(",");treeMap.put(Integer.parseInt(split[1]), split[0]);}reader.close();//=======================================写入BufferedWriter writer = new BufferedWriter(new FileWriter("operate/src/operate418/silence/user.txt", true));Set<Map.Entry<Integer, String>> entries = treeMap.entrySet();writer.newLine();writer.write("----排序后----");writer.newLine();for (Map.Entry<Integer, String> entry : entries) {writer.write(entry.getValue() + "," + entry.getKey());writer.newLine();writer.flush();}writer.close();}
}

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张三,18
狗屎,17
李四,19
王五,17
赵六,22
皮蛋,19
小花,23
小黄,19

----排序后----
王五,17
狗屎,17
张三,18
小黄,19
皮蛋,19
李四,19
赵六,22
小花,23