所以我有一个包含大量天气数据的大文件。我必须将大文件中的每一行分配到相应的状态文件中。因此，将有总共50个具有自己数据的新状态文件。
大文件包含约100万行记录，如下所示：
COOP:166657,'NEW IBERIA AIRPORT ACADIANA REGIONAL LA US',200001,177,553
虽然电台的名称可能会有所不同，但字数也不同。
这是我正在使用的正则表达式：
Pattern p = Pattern.compile(".* ([A-Z][A-Z]) US.*");
Matcher m = p.matcher(line);
当我运行程序时，仍然存在无法找到模式的行的实例。
这是我的计划：
package climate;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Arrays;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* This program will read in a large file containing many stations and states,
* and output in order the stations to their corresponding state file.
*
* Note: This take a long time depending on processor. It also appends data to
* the files so you must remove all the state files in the current directory
* before running for accuracy.
*
* @author Marcus
*
*/
public class ClimateCleanStates {
public static void main(String[] args) throws IOException {
Scanner in = new Scanner(System.in);
System.out
.println("Note: This program can take a long time depending on processor.");
System.out
.println("It is also not necessary to run as state files are in this directory.");
System.out
.println("But if you would like to see how it works, you may continue.");
System.out.println("Please remove state files before running.");
System.out.println("\nIs the States directory empty?");
String answer = in.nextLine();
if (answer.equals("N")) {
System.exit(0);
in.close();
}
System.out.println("Would you like to run the program?");
String answer2 = in.nextLine();
if (answer2.equals("N")) {
System.exit(0);
in.close();
}
String[] statesSpaced = new String[51];
File statefile, dir, infile;
// Create files for each states
dir = new File("States");
dir.mkdir();
infile = new File("climatedata.csv");
FileReader fr = new FileReader(infile);
BufferedReader br = new BufferedReader(fr);
String line;
System.out.println();
// Read in climatedata.csv
// Probably need to implement ClimateRecord class
final long start = System.currentTimeMillis();
while ((line = br.readLine()) != null) {
// Remove instances of -9999
if (!line.contains("-9999")) {
Pattern p = Pattern.compile("^.* ([A-Z][A-Z]) US.*$");
Matcher m = p.matcher(line);
String stateFileName = null;
if(m.find()){
//System.out.println(m.group(1));
stateFileName = m.group(1);
} else {
System.out.println("Could not find abbreviation");
}
/*
stateFileName = "States/" + stateFileName + ".csv";
statefile = new File(stateFileName);
FileWriter stateWriter = new FileWriter(statefile, true);
stateWriter.write(line + "\n");
// Progress reporting
System.out.printf("Writing [%s] to file [%s]\n", line,
statefile);
stateWriter.flush();
stateWriter.close();
*/
}
}
System.out.println("Elapsed " + (System.currentTimeMillis() - start) + " ms");
br.close();
fr.close();
in.close();
}
}
答案 0 :(得分：1)
取决于您想要提取的内容，但是如果您使用的是
类型的模式Pattern.compile("(.*):(.*),'(.*)',(.*),(.*),(.*)");
Matcher m = p.matcher(line);
if(m.find()) {
// here you can use with i from 1 to 6
m.group(i);
//and access the 6 tokens:
//COOP
//166657
//NEW IBERIA AIRPORT ACADIANA REGIONAL LA US
//200001
//177
//553
}
答案 1 :(得分：1)
我认为你需要查看函数，他们断言某些事情应该在你匹配但不包含在结果中的表达式之前或之后。
(?<= )[A-Z][A-Z](?= US)
(?<= )必须是
[A-Z][A-Z]正好两个大写字母
(?= US)必须是空格，而
通过环顾四周可能会更加强大：（？= US）可能是（？= US＆＃39 ;,）。
答案 2 :(得分：0)
而不是
".* ([A-Z][A-Z]) US.*"
如果某些州没有缩写，也许可以尝试：
" ([a-z][A-Z])+ US'"
答案 3 :(得分：0)
要特别注意该行的^开头，非贪婪的群组(.*?)，行尾$，DOTALL和MULTILINE。
Pattern regex = Pattern.compile("^(.*?):(.*?),'(.*?)',(.*?),(.*?),(.*?)$", Pattern.DOTALL | Pattern.MULTILINE);
正则表达式DEMO：
https://regex101.com/r/bX0rS3/1
Live JAVA示例：
正则表达式解释：
^(.*?):(.*?),'(.*?)',(.*?),(.*?),(.*?)$
Options: Case sensitive; Exact spacing; Dot matches line breaks; ^$ match at line breaks; Default line breaks
Assert position at the beginning of a line (at beginning of the string or after a line break character) (carriage return and line feed, next line, line separator, paragraph separator) «^»
Match the regex below and capture its match into backreference number 1 «(.*?)»
Match any single character «.*?»
Between zero and unlimited times, as few times as possible, expanding as needed (lazy) «*?»
Match the character “:” literally «:»
Match the regex below and capture its match into backreference number 2 «(.*?)»
Match any single character «.*?»
Between zero and unlimited times, as few times as possible, expanding as needed (lazy) «*?»
Match the character string “,'” literally «,'»
Match the regex below and capture its match into backreference number 3 «(.*?)»
Match any single character «.*?»
Between zero and unlimited times, as few times as possible, expanding as needed (lazy) «*?»
Match the character string “',” literally «',»
Match the regex below and capture its match into backreference number 4 «(.*?)»
Match any single character «.*?»
Between zero and unlimited times, as few times as possible, expanding as needed (lazy) «*?»
Match the character “,” literally «,»
Match the regex below and capture its match into backreference number 5 «(.*?)»
Match any single character «.*?»
Between zero and unlimited times, as few times as possible, expanding as needed (lazy) «*?»
Match the character “,” literally «,»
Match the regex below and capture its match into backreference number 6 «(.*?)»
Match any single character «.*?»
Between zero and unlimited times, as few times as possible, expanding as needed (lazy) «*?»
Assert position at the end of a line (at the end of the string or before a line break character) (carriage return and line feed, next line, line separator, paragraph separator) «$»
答案 4 :(得分：0)
您可以使用以下命令验证它是美国州的缩写：
\s(?:(A[KLRZ]|C[AOT]|D[CE]|FL|GA|HI|I[ADLN]|K[SY]|LA|M[ADEINOST]|N[CDEHJMVY]|O[HKR]|P[AR]|RI|S[CD]|T[NX]|UT|V[AIT]|W[AIVY])(?:\sUS'|'))