package experiment5.exp2;
import java.io.File;
import java.io.FileNotFoundException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.*;
/*有不同年份的温度数据temperature.txt，要求日期按年月升序、温度按降序 将温度数据排列出来。(注意是年月,日不参于比较)
*比较日期查看:
* File file = new File("weather.txt");
Scanner scanner = new Scanner(file);
*/
public class Temperature {
public static void main(String[] args) {
List<String> list=new ArrayList<>();
String s;
File file = new File("D:\\OneDrive\\Java\\ProjectCodeInIDEA\\src\\experiment5\\exp2\\weather.txt");
try {
Scanner scanner = new Scanner(file);//读取数据
//主体部分:
/*对于nextLine()方法 :
* 返回:the line that was skipped
遇错误 抛出:
java.util.NoSuchElementException – if no line was found
IllegalStateException – if this scanner is closed*/
for(s=scanner.nextLine();scanner.hasNextLine();s=scanner.nextLine()){
list.add(s);//尽管程序在运行过程中出错,但是能够执行的部分还是执行了
}/*至此,成功读入数据到list中*/
/*下面开始做解析和比较处理*/
Comparator<String> comparator = new Comparator<String>() {
public int compare(String o1, String o2) {
/*用compareTo()比较需要注意日期的格式要求.*/
int ret=(o1.substring(0, 7)+"-00").compareTo(o2.substring(0, 7)+"-00");
if(ret==0){
return Integer.parseInt(o2.substring(20, 22))-Integer.parseInt(o1.substring(20, 22));
}
return ret;
}
/* @Override
public boolean equals(Object obj) {
return false;
}*/
};
Collections.sort(list,comparator);
/*处理打印效果*/
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-M-d");/*string_date_format*/
for(String x:list){
try {
Date sd=sdf.parse(x.substring(0,19));/*根据sdf日期格式对象来调用parse()解析表达日期的字符串,返回一个日期对象sd(string->date)*/
// System.out.println(x.substring(0, 10)+" "+x.substring(20, 22)+".0");
System.out.println(sdf.format(sd)+"\t"+x.substring(20, 22)+".0");/*调用日期格式对象sdf的format()方法(该方法会返回一个字符串)来格式化日期对象sd*/
/*java.text.DateFormat @NotNull
public final String format(java.util.Date date)
参数:
date – the time value to be formatted into a date-time string.
返回:
the formatted date-time string.
*/
} catch (ParseException e) {
e.printStackTrace();
}
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
}
测试数据:weather.txt
2015-10-01 14:21:08 34c
2015-10-02 14:01:33 36c
2016-01-01 11:21:06 32c
2016-10-01 12:01:12 37c
2017-12-01 12:11:58 23c
2016-10-02 12:21:03 41c
2016-10-03 12:24:22 27c
2017-07-01 12:31:51 41c
2017-07-02 12:11:02 43c
2017-07-03 12:05:03 44c
2015-06-01 10:21:01 35c
2015-06-05 13:01:33 33c
2015-06-04 11:11:08 32c
2015-06-02 13:07:14 33c
2016-08-11 10:41:25 39c
2016-08-07 15:24:52 36c
2017-09-12 11:16:47 40c
2017-09-03 14:29:53 38c
2017-09-10 16:01:12 37c
2017-09-01 10:25:43 36c
2018-01-01 01:30:18 10c
2018-01-02 03:30:07 10c
2018-03-07 11:09:10 12c
2018-03-21 22:01:20 15c
2018-03-11 21:47:06 11c
2018-03-30 05:03:58 10c
2018-06-01 12:04:10 25c
2018-06-11 20:30:30 21c
2018-06-30 14:02:28 30c
2018-10-01 14:05:14 21c
2018-10-25 12:30:09 25c
2018-10-27 23:12:33 23c
2018-10-30 09:50:00 24c
2019-06-01 07:12:42 28c
2019-06-04 12:30:42 32c
2019-06-10 19:02:19 30c
2019-06-25 15:01:50 36c
2019-09-01 09:22:12 30c
2019-09-11 10:20:02 22c
2019-09-20 09:22:12 27c
2019-09-25 18:08:55 20c
2020-01-01 12:12:32 18c
2020-01-04 11:30:42 10c
2020-01-10 09:23:29 11c
2020-06-05 11:21:30 36c
2020-06-12 15:01:10 36c
2020-06-26 15:13:15 36c
2020-06-28 20:04:18 36c
2020-09-01 09:22:12 30c
2020-09-11 10:20:02 22c
2020-09-20 09:22:12 27c
2020-09-30 18:08:55 20c
输出:
