Java 中对日期时间按区间定位

【问题】

I have a csv records with timestamps like or every 5 minutes:

- 2015/05/19 16:15:00

- 2015/05/19 16:20:00

- 2015/05/19 16:35:00

- 2015/05/19 16:10:00

- 2015/05/19 16:55:00

I’m using an array to compare if the dates per record is within 15 minutes:

ArrayList<String> per15Min = new ArrayList<String>() {{
 add("00,15");
 add("15,30");
 add("30,45");
 add("45,00");
}};

What I do is read each record, split it based on “,” to extract the Dates:

private SimpleDateFormat csvDateFormat = new SimpleDateFormat("yyyy/MM/dd HH🇲🇲ss");
private SimpleDateFormat fileDateFormat = new SimpleDateFormat("yyyyMMddHHmm");
// Loop thru each record
while ((perLine = br.readLine()) != null) {
 // Store date per record in a string
 String[] perColumn = perLine.split(",", -1);
 String date = perColumn[0];
 // Convert record date to yyyyMMddHHmm
 Date subDateP = csvDateFormat.parse(csvDate);
 String subDateF = fileDateFormat.format(subDateP);
 // Extract the date without the day (dd)
 String subDate = subDateF.substring(0,10);
 for (int j = 0 ; j < per15Min.size() ; j++) {
 String[] s = per15Min.get(j).split(",", -1);
 String m1 = s[0];
 String m2 = s[1];
 // All dates are in a yyyyMMddHHmm format
 Date before = fileDateFormat.parse(subDate + m1);
 Date after = fileDateFormat.parse(subDate + m2);
 Date csvRd = fileDateFormat.parse(date);
 System.out.println("DATE " + before + " : " + after + " : " + csvRd);
 // Having problems doing date comparison
 if ((before.compareTo(csvRd) >= 0) && (csvRd.compareTo(after) < 0)) {
 System.out.println("DATE HERE" + before + " : " + after + " : " + csvRd);
 }
 }
}

As you can see based from the sysout it doesn’t seem to work:

DATE HEREWed May 20 07:30:00 SGT 2015 : Wed May 20 07:45:00 SGT 2015 : Wed May 20 07:30:00 SGT 2015
DATE HEREWed May 20 07:30:00 SGT 2015 : Wed May 20 07:45:00 SGT 2015 : Wed May 20 07:25:00 SGT 2015
DATE HEREWed May 20 07:30:00 SGT 2015 : Wed May 20 07:45:00 SGT 2015 : Wed May 20 07:20:00 SGT 2015
DATE HEREWed May 20 07:30:00 SGT 2015 : Wed May 20 07:45:00 SGT 2015 : Wed May 20 07:15:00 SGT 2015
DATE HEREWed May 20 07:30:00 SGT 2015 : Wed May 20 07:45:00 SGT 2015 : Wed May 20 07:10:00 SGT 2015

What I need is something like if the timestamp (per 5 min) is within the 15 minute array it will enter the condition:

00-10 minutes must enter at 00,15
15-25 minutes must enter at 15,30
30-40 minutes must enter at 30,45
45-55 minutes must enter at 45,00

【回答】

给每条时间标注所属区间范围，硬编码需要两层循环，日期的处理也比较麻烦，推荐用集算器，SPL 代码如下：

	A
1	=file("D:/file.csv").import@c()
2	=[0,15,30,45,60]
3	=A1.new(~:point,A2.pseg(minute(datetime(~.#1,"yyyy/MM/dd HH🇲🇲SS"))):range)
4	=A3.run(string(A2.m(range))+","+string(A2.m(range+1)):range)

A1：读取 csv 数据

A3：使用 pseg 函数返回数据所属的区间编号

A4：通过区间编号获取数据所属的区间，生成最终结果

集算器不仅可以进行关联计算，还可以通过 JDBC 与 JAVA 集成，参考《Java 如何调用 SPL 脚本》。