I am still new to java. I am having a bit problems with the java syntax. My Program should do the following procedure:
1) It takes a csv file as an input.
2) It takes an excel file as an input.
3) It should iterate over the first columns of the two files where the dates are written.
4) Update the excel file by adding the information from the csv sheet and save its changes.
where I have the two input examples and how the result excel sheet should look like.
Two Input files:
export-csv-input.csv
export-excel-input.xlsx
The updated excel file should look like:
export-excel-output.xlsx
My Java Code yet:
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.Reader;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVParser;
import org.apache.commons.csv.CSVRecord;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.DataFormatter;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
public class CsvToExcelConverter {
public static final String SAMPLE_XLSX_FILE_PATH =
"C:/Users/blawand/Desktop/CSV_to_Excel/export-excel-test.xlsx";
public static final String SAMPLE_CSV_FILE_PATH =
"C:/Users/blawand/Desktop/CSV_to_Excel/export-csv-test.csv";
public static List<String> dates_csv = new ArrayList<>();
public static List<String> dates_excel = new ArrayList<>();
public static void main(String[] args) throws IOException,
InvalidFormatException {
try (Reader reader =
Files.newBufferedReader(Paths.get(SAMPLE_CSV_FILE_PATH));
CSVParser csvParser = new CSVParser(reader, CSVFormat.DEFAULT);)
{
for (CSVRecord csvRecord : csvParser) {
// Accessing Values by Column Index
String name = csvRecord.get(0);
dates_csv.add(name);
}
dates_csv.remove(0);
}
FileInputStream fsIP = new FileInputStream(new
File(SAMPLE_XLSX_FILE_PATH));
/*
* ==================================================================
Iterating over all the
* rows and columns in a Sheet (Multiple ways)
* ==================================================================
*/
// Getting the Sheet at index zero
XSSFWorkbook workbook = new XSSFWorkbook(fsIP);
XSSFSheet sheet = workbook.getSheetAt(0);
// Get the Cell at index 2 from the above row
// Cell cell1 = sheet.getRow(1).getCell(0);
// for (int i = 0; i < dates_excel.size(); i++) {
// XSSFRow rowtest = sheet.createRow((short) i + 1);
// rowtest.createCell(0).setCellValue(dates_csv.get(i));
//
// }
// cell1.setCellValue(dates_csv.get(0));
// Create a DataFormatter to format and get each cell's value as
String
DataFormatter dataFormatter = new DataFormatter();
for (int rowIndex = 1; rowIndex <= sheet.getLastRowNum(); rowIndex++)
{
Row row = sheet.getRow(rowIndex);
if (row != null) {
Cell cell = row.getCell(0); // getColumn(0)
if (cell != null) {
// Found column and there is value in the cell.
// String cellValueMaybeNull = cell.getStringCellValue();
String cellValueMaybeNull =
dataFormatter.formatCellValue(cell);
// String to number set
dates_excel.add(cellValueMaybeNull);
}
}
}
System.out.println(dates_csv);
System.out.println(dates_csv.size());
System.out.println(dates_excel);
System.out.println(dates_excel.size());
while (dates_excel == dates_excel) {
System.out.println("Yes");
break;
}
fsIP.close();
FileOutputStream output_file = new FileOutputStream(new
File(SAMPLE_XLSX_FILE_PATH));
workbook.write(output_file);
output_file.close();
}
}
I read already the two files but i am having problems with updating the excel file and adding the project names to the correct dates. And if the same date has been written two or more times in the csv sheet.
Which information would you like also to know?
I would be thankful for every help or advice!
I have an example for you, mostly explained by code comments. Nevertheless, the code basically does the following:
Takes file paths of the xlsx and csv file in the constructor.
When updating, it first reads the content of the csv file into a Map with a LocalDate as key and a List<String> as values.
Then it goes through the rows of the workbook skipping the header row and comparing the dates in column one with the keys of the Map<LocalDate, List<String>>. If the map contains that key, it starts checking the cells in that row for present values and keeps them in a list in order to not write them later.
Then it starts writing the values into the cells of the row with the key date.
I hope this helps.
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.time.Instant;
import java.time.LocalDate;
import java.time.ZoneId;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Date;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
public class CsvXlsxUpdater {
private static final DateTimeFormatter DATE_TIME_FORMATTER_CSV = DateTimeFormatter.ofPattern("dd.MM.yyyy");
private Path csvFilePath;
private Path xlsxFilePath;
private XSSFWorkbook workbook;
private XSSFSheet sheet;
private Map<LocalDate, List<String>> csvContent = new TreeMap<LocalDate, List<String>>();
private ZoneId zoneId = ZoneId.systemDefault();
public CsvXlsxUpdater(String pathToCsvFile, String pathToXlsxFile) {
csvFilePath = Paths.get(pathToCsvFile);
xlsxFilePath = Paths.get(pathToXlsxFile);
}
/**
* Reads the content of the csv file into the corresponding class variable,
* which is a {@link TreeMap} that has a {@link LocalDate} as key and a
* {@link List<String>} as values.
*/
private void readCsvContent() {
List<String> csvLines;
try {
csvLines = Files.readAllLines(csvFilePath);
for (int i = 1; i < csvLines.size(); i++) {
String line = csvLines.get(i);
String[] splitValues = line.split(",");
if (splitValues.length > 1) {
List<String> lineValues = Arrays.asList(splitValues);
List<String> projects = getProjectValuesFrom(lineValues);
LocalDate localDate = LocalDate.parse(lineValues.get(0), DATE_TIME_FORMATTER_CSV);
if (csvContent.containsKey(localDate)) {
projects.forEach((String project) -> {
List<String> csvProjects = csvContent.get(localDate);
if (!csvProjects.contains(project)) {
csvProjects.add(project);
}
});
} else {
csvContent.put(localDate, projects);
}
} else {
LocalDate localDate = LocalDate.parse(splitValues[0], DATE_TIME_FORMATTER_CSV);
csvContent.put(localDate, new ArrayList<String>());
}
}
} catch (IOException e) {
System.err.println("CANNOT FIND OR READ CSV FILE: " + e.getMessage());
e.printStackTrace();
} catch (UnsupportedOperationException e) {
System.err.println("UNSUPPORTED OPERATION: " + e.getMessage());
e.printStackTrace();
}
}
/**
* Gets the corresponding {@link LocalDate} from a given (and deprecated)
* {@link Date}
*
* @param date the deprecated {@link Date} object
* @return the corresponding {@link LocalDate}
*/
private LocalDate parseLocalDateFrom(Date date) {
Instant instantDate = date.toInstant();
return instantDate.atZone(zoneId).toLocalDate();
}
/**
* Takes a list of read values from the csv file and returns a list containing
* all the values of the given list <strong>except from the first
* element</strong>, which is a {@link String} representation of a date and
* should be treated differently in this context.
*
* @param values the original list of {@link String}s
* @return another list without the first element of the given list
*/
private List<String> getProjectValuesFrom(List<String> values) {
List<String> projectValues = new ArrayList<String>();
for (int i = 1; i < values.size(); i++) {
String value = values.get(i);
if (!value.equals("")) {
projectValues.add(value);
}
}
return projectValues;
}
/**
* Updates the workbook with the values read from the csv file
*/
public void updateWorkbook() {
readCsvContent();
try {
FileInputStream fis = new FileInputStream(xlsxFilePath.toAbsolutePath().toString());
workbook = new XSSFWorkbook(fis);
sheet = workbook.getSheetAt(0);
// iterate over the rows
Iterator<Row> rowIterator = sheet.rowIterator();
while (rowIterator.hasNext()) {
XSSFRow row = (XSSFRow) rowIterator.next();
if (row.getRowNum() == 0) {
// skip this or set updated headers
} else {
// check if the csvContent contains the value of cell(0)
LocalDate dateKey = parseLocalDateFrom(row.getCell(0).getDateCellValue());
if (csvContent.containsKey(dateKey)) {
// if yes, get list-value of the key
List<String> values = csvContent.get(dateKey);
// check if there are values
if (values != null) {
if (values.size() > 0) {
// if there are, then go checking the cell values
List<String> projectsInXlsx = new ArrayList<String>();
Iterator<Cell> cellIterator = row.cellIterator();
int lastColumnIndex = 1;
// go through all cells with a value except from the first one
while (cellIterator.hasNext()) {
Cell cell = cellIterator.next();
// skip the first column as it contains the date
if (cell.getColumnIndex() != 0) {
lastColumnIndex = cell.getColumnIndex();
System.out.println("Accessing cell in column " + lastColumnIndex);
// if there is a cell with a value
if (cell.getStringCellValue() != null) {
if (!cell.getStringCellValue().equals("")) {
// check if the value in the cell is also in the csv values
if (values.contains(cell.getStringCellValue())) {
projectsInXlsx.add(cell.getStringCellValue());
lastColumnIndex++;
}
}
}
}
}
// now go through the values of the csv file
int offset = 0; // cell column offset for more than one entry per date
for (String value : values) {
if (!projectsInXlsx.contains(value)) {
// create a cell after the last one with a value
row.createCell(lastColumnIndex + offset).setCellValue(value);
offset++;
}
}
}
}
}
}
}
fis.close();
FileOutputStream fileOutputStream = new FileOutputStream(xlsxFilePath.toAbsolutePath().toString());
workbook.write(fileOutputStream);
fileOutputStream.flush();
fileOutputStream.close();
workbook.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
In a main method, you would just have to call the constructor, pass the file paths as Strings and then call the updateWorkbook() method, because it internally reads the csv first.
Example:
public class CsvXlsxMain {
private static final String CSV_FILE_PATH = "S:\\ome\\example\\path\\to\\csv-input.csv";
private static final String XLSX_FILE_PATH = "S:\\ome\\example\\path\\to\\excel-input.xlsx";
public static void main(String[] args) {
CsvXlsxUpdater cxu = new CsvXlsxUpdater(CSV_FILE_PATH, XLSX_FILE_PATH);
cxu.updateWorkbook();
}
}
Please keep in mind that this CODE IS NOT FULLY TESTED, there may be problems with alternating resources in future If you need, go testing it with various xlsx and csv inputs that fit your requirements.
I haven't used any library to parse the csv file!
I hope this helps you a little…
来源：https://stackoverflow.com/questions/52254215/updating-excel-sheet-values-based-on-a-csv-sheet-with-apache-poi