在Java中从逗号和标题分隔的文件中读取时间
在Java中从逗号和标题分隔的文件中读取时间
提问于 2018-10-23 04:06:20
我在一个文件里有一个列表，里面有很多次。我的目标是将所有的时间都放在它们自己的字符串数组中，分别称为time1、time2和time3。该文件如下所示：
time1, 5:01,3:21,4:05,1:52 time2, 2:11,6:35,2:00,5:00 time3, 12:09,
11:35, 9:02我试着把读到的每一行都拆分，然后把它转换成记号，用逗号隔开。然而，这似乎不是一个有效的解决方案，因为第一个元素总是以空格开头，而最后一个元素没有逗号。我想知道是否有人知道解决这个问题的方法。
这是我到目前为止想出的代码：
public void read_file(){
try{
times = new Scanner(new File("times.csv"));
read_file();
}
catch(Exception e){
System.out.printf("Could not find file\n");
}
}
public void read_file(){
while(times.hasNextLine()){
i++;
String a = times.nextLine();
String time[] = a.split(",");
//would only add first 4 elements
if(i < 4){
timeList1.add(time[i])
}
}
}这里的问题是，我不知道如何检查我必须继续运行的元素数量，因为列表中的次数是不可预测的。唯一保持不变的是，总会有3个时间列表，分别称为time1、time2和time3。
回答 3
Stack Overflow用户
发布于 2018-10-23 05:42:48
这是一个单元测试，它可以做你想做的事情。我不得不稍微格式化一下你的输入字符串。您应该能够以最少的更改为您完成此工作。
import org.junit.Test;
import java.time.LocalDate;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* @author Dr. Parameter
*/
public class TimeParser {
private final DateTimeFormatter formatter = DateTimeFormatter.ofPattern("k:mm");
@Test
public void test(){
// Test input
String times = "time1, 5:01,3:21,4:05,1:52, time2, 2:11,6:35,2:00,5:00, time3, 12:09,11:35, 9:02";
// Set up Objects used to collect
String currentKey = "";
HashMap<String, List<LocalTime>> timeMap = new HashMap();
// Iterate though list
String[] lineBreaks = times.split("\n");
for(String line : lineBreaks){
String[] csvBreaks = line.split(",");
for(String csv : csvBreaks){
//try to parse a time and add it to the key set, add a new key if there is a failure
try {
timeMap.get(currentKey).add(LocalTime.parse(csv.trim(), formatter));
} catch (Exception ex){
currentKey = csv;
timeMap.put(currentKey, new ArrayList<>());
}
}
}
//Print result:
for(Map.Entry<String, List<LocalTime>> entry : timeMap.entrySet()){
System.out.println("times for key: " + entry.getKey());
for(LocalTime time : entry.getValue()){
System.out.println("\t" + time);
}
}
}
}Stack Overflow用户
发布于 2018-10-23 06:14:26
下面是另一种更简单的方法：
public class ReadTimes {
private Map<String, List<String>> timeLists = new HashMap();
public void read_file() {
try {
Scanner times = new Scanner(new File("times.csv"));
read_file(times);
} catch (Exception e) {
System.out.printf("Could not find file\n");
}
}
public void read_file(Scanner times) {
String label=null;
while (times.hasNextLine()) {
String time[] = times.nextLine().trim().split("[, ]+");
for (String timeString : time) {
if (timeString.startsWith("time")) {
label = timeString;
timeLists.put(label, new ArrayList());
} else if (label != null) {
timeLists.get(label).add(timeString);
}
}
}
// dump the map of arraylists for demonstration purposes...
for (Entry<String,List<String>> timeEntry : timeLists.entrySet()) {
System.out.println(timeEntry);
}
}
public static void main(String[] args) {
ReadTimes rt = new ReadTimes();
rt.read_file();
}
}给定问题中显示的输入数据，将生成以下输出：
time1=[5:01, 3:21, 4:05, 1:52]
time2=[2:11, 6:35, 2:00, 5:00]
time3=[12:09, 11:35, 9:02]Stack Overflow用户
发布于 2018-10-23 06:24:05
因为你确定你想要3个字符串数组，下面的代码以"time“作为分隔符拆分初始字符串，删除开头的"1, "，"2, "，"3, "，修剪并删除结尾的,，最后在删除所有空格后，以,作为分隔符拆分每一项，生成3个字符串数组。
String times = "time1, 5:01,3:21,4:05,1:52, time2, 2:11,6:35,2:00,5:00, time3, 12:09,11:35, 9:02";
String[] splitted = times.split("time");
// exclude 0th item which is ""
for (int i = 1; i < splitted.length; i++) {
splitted[i] = splitted[i].trim();
int index = splitted[i].indexOf(" ");
if (splitted[i].endsWith(","))
splitted[i] = splitted[i].substring(index + 1, splitted[i].length() - 1);
else
splitted[i] = splitted[i].substring(index + 1);
splitted[i] = splitted[i].replaceAll(" ", "");
}
try { // just in case
String time1[] = splitted[1].split(",");
System.out.println(Arrays.toString(time1));
String time2[] = splitted[2].split(",");
System.out.println(Arrays.toString(time2));
String time3[] = splitted[3].split(",");
System.out.println(Arrays.toString(time3));
} catch (Exception e) {
e.printStackTrace();
}打印3个字符串数组：
[5:01, 3:21, 4:05, 1:52]
[2:11, 6:35, 2:00, 5:00]
[12:09, 11:35, 9:02]页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/52937021
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