我有一个文件，其中一列包含多个值。我试图使用带有以下代码的Java读取此文件：
ArrayList<String> linesList1 = new ArrayList<>();
ArrayList<String> roadlinkid = new ArrayList<>();
ArrayList<String> road_name_orignal = new ArrayList<>();
ArrayList<String> road_name_copy = new ArrayList<>();
ArrayList<String[]> networkmember_href = new ArrayList<>();
ArrayList<String> road_fid = new ArrayList<>();
// Input of file which needs to be parsed
String csvFile1 = "RoadData.csv";
BufferedReader csvReader1;
// Data split by ',' in CSV file
String csvSplitBy = ",";
try {
String line;
csvReader1 = new BufferedReader(new FileReader(csvFile1));
while ((line = csvReader1.readLine()) !=null) {
linesList1.add(line);
}
csvReader1.close();
}
catch (IOException e) { e.printStackTrace(); }
for (int i = 0; i < linesList1.size(); i++) {
String[] data = linesList1.get(i).split(csvSplitBy);
road_fid.add( data[1]);
road_name_orignal.add( data[9]);
if (data[9].contains("{")) {
String[] xy = data[9].replaceAll("\\{|\\}", "").split(",");
int leng = xy.length;
String[] networkmember = new String [leng];
for ( int n = 0 ; n < leng ; n++) {
networkmember[n] = xy [n];
}
networkmember_href.add(networkmember);
}
}
此代码运行良好，但是问题在于该代码将列中的每个值作为单独的列处理。因此，它返回错误的数据。
文件： http://s000.tinyupload.com/?file_id=47090134488569683648
想法是通过比较RoadData.csv中的road_fid和RoadLink.csv中的roadlink_fid，从RoadData.csv中查找道路名称并将其写入RoadLink.csv中。不幸的是，我可以找到一种处理具有多值的列的方法。请提供任何建议。
先谢谢了。
答案 0 :(得分：0)
下面是一些用于解析文件的代码，您可以添加其他处理以解析其中具有列表的字段，或者将诸如changedate和reasonforchange之类的列表合并到包含两个字段的对象列表中数据例如一个List<ChangeInfo>，其中ChangeInfo同时拥有changedate和reasonforchange。
我仍然建议使用csv解析器，但是此代码对于此特定用例应该足够好。彻底测试。
主要：
public static void main(String[] args){
List<RoadLinkRecord> records = parse("path\\to\\RoadLink.csv");
// display all the records
for (RoadLinkRecord record : records) {
System.out.println(record);
}
}
CSV解析：
private static final Pattern csvFieldPattern =
Pattern.compile("(?<=[$,])(\"(\"\"|[^\"])*\"|[^,]*)");
/** This parse method requires the CSV file to have a header row */
public static List<RoadLinkRecord> parse(String csvFilePath) {
// TODO accept Reader or maybe InputStream rather than file path
File f = new File(csvFilePath);
List<RoadLinkRecord> records = new ArrayList<>();
try (BufferedReader br = new BufferedReader(new FileReader(f));) {
// get the header fields
String line = br.readLine();
List<String> headers = new ArrayList<>();
{
Matcher matcher = csvFieldPattern.matcher(line);
while (matcher.find())
headers.add(matcher.group());
}
// iterate through record fields
int recordNum = 0;
while ((line = br.readLine()) != null) {
recordNum++;
// allocate array to hold the fields
String[] fields = new String[headers.size()];
// use matcher to get each of the fields
Matcher matcher = csvFieldPattern.matcher(line);
for (int i = 0; i < headers.size(); i++) {
if (!matcher.find()) {
throw new IllegalArgumentException(
"Couldn't find field '" + headers.get(i) + "' for record " + recordNum);
}
fields[i] = matcher.group();
}
if (matcher.find()) {
throw new IllegalArgumentException("Found excess fields in record " + recordNum);
}
// add the record from this line
records.add(new RoadLinkRecord(recordNum, fields));
}
} catch (IOException e) {
// TODO trouble reading the file
} catch (IllegalArgumentException e) {
// TODO error while parsing the file
}
return records;
}
数据容器：
public class RoadLinkRecord {
private final int recordNumber;
private final String roadlink_fid;
private final String version;
private final String versiondate;
private final String changedate;
private final String reasonforchange;
private final String descriptivegroup;
private final String descriptiveterm;
private final String natureofroad;
private final String length;
private final String directednode_href;
private final String directednode_orientation;
private final String directednode_gradeseparation;
private final String referencetotopographicarea_href;
private final String theme;
private final String filename;
private final String wkb_geometry;
private final String roadnumber;
private final String dftname;
private final String fid;
private final String roadname;
public RoadLinkRecord(final int recordNumber, final String[] csvFields) {
if (csvFields.length != 20) {
throw new IllegalArgumentException(
"Wrong number of fields for a RoadLinkRecord! Expected 20, found "
+ csvFields.length);
}
this.recordNumber = recordNumber;
this.roadlink_fid = processStringField(csvFields[0]);
this.version = processStringField(csvFields[1]);
this.versiondate = processStringField(csvFields[2]);
this.changedate = processStringField(csvFields[3]);
this.reasonforchange = processStringField(csvFields[4]);
this.descriptivegroup = processStringField(csvFields[5]);
this.descriptiveterm = processStringField(csvFields[6]);
this.natureofroad = processStringField(csvFields[7]);
this.length = processStringField(csvFields[8]);
this.directednode_href = processStringField(csvFields[9]);
this.directednode_orientation = processStringField(csvFields[10]);
this.directednode_gradeseparation = processStringField(csvFields[11]);
this.referencetotopographicarea_href = processStringField(csvFields[12]);
this.theme = processStringField(csvFields[13]);
this.filename = processStringField(csvFields[14]);
this.wkb_geometry = processStringField(csvFields[15]);
this.roadnumber = processStringField(csvFields[16]);
this.dftname = processStringField(csvFields[17]);
this.fid = processStringField(csvFields[18]);
this.roadname = processStringField(csvFields[19]);
}
private static String processStringField(String field) {
// consider empty fields as null
if (field.isEmpty()) {
return null;
}
// strip double quotes and replace any escaped quotes
final int endIndex = field.length() - 1;
if (field.charAt(0) == '"' && field.charAt(endIndex) == '"') {
return field.substring(1, endIndex).replace("\"\"", "\"");
}
return field;
}
public int getRecordNumber() { return recordNumber; }
public String getRoadlink_fid() { return roadlink_fid; }
public String getVersion() { return version; }
public String getVersiondate() { return versiondate; }
public String getChangedate() { return changedate; }
public String getReasonforchange() { return reasonforchange; }
public String getDescriptivegroup() { return descriptivegroup; }
public String getDescriptiveterm() { return descriptiveterm; }
public String getNatureofroad() { return natureofroad; }
public String getLength() { return length; }
public String getDirectednode_href() { return directednode_href; }
public String getDirectednode_orientation() { return directednode_orientation; }
public String getDirectednode_gradeseparation() { return directednode_gradeseparation; }
public String getReferencetotopographicarea_href() { return referencetotopographicarea_href; }
public String getTheme() { return theme; }
public String getFilename() { return filename; }
public String getWkb_geometry() { return wkb_geometry; }
public String getRoadnumber() { return roadnumber; }
public String getDftname() { return dftname; }
public String getFid() { return fid; }
public String getRoadname() { return roadname; }
@Override
public String toString() {
return "roadlink_fid= " + roadlink_fid + "; version= " + version + "; versiondate= "
+ versiondate + "; changedate= " + changedate + "; reasonforchange= "
+ reasonforchange + "; descriptivegroup= " + descriptivegroup + "; descriptiveterm= "
+ descriptiveterm + "; natureofroad= " + natureofroad + "; length= " + length
+ "; directednode_href= " + directednode_href + "; directednode_orientation= "
+ directednode_orientation + "; directednode_gradeseparation= "
+ directednode_gradeseparation + "; referencetotopographicarea_href= "
+ referencetotopographicarea_href + "; theme= " + theme + "; filename= " + filename
+ "; wkb_geometry= " + wkb_geometry + "; roadnumber= " + roadnumber + "; dftname= "
+ dftname + "; fid= " + fid + "; roadname= " + roadname + ";";
}
}