Read and Write Excel File in Java using Apache POI
Gradle Dependencies
// https://mvnrepository.com/artifact/org.apache.poi/poi implementation 'org.apache.poi:poi:5.2.2' // https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml implementation 'org.apache.poi:poi-ooxml:5.2.2'
Writing an Excel File
package com.howtodoinjava.demo.poi; //import statements public class WriteExcelDemo { public static void main(String[] args) { //Blank workbook XSSFWorkbook workbook = new XSSFWorkbook(); //Create a blank sheet XSSFSheet sheet = workbook.createSheet("Employee Data"); //This data needs to be written (Object[]) Map<String, Object[]> data = new TreeMap<String, Object[]>(); data.put("1", new Object[] {"ID", "NAME", "LASTNAME"}); data.put("2", new Object[] {1, "Amit", "Shukla"}); data.put("3", new Object[] {2, "Lokesh", "Gupta"}); data.put("4", new Object[] {3, "John", "Adwards"}); data.put("5", new Object[] {4, "Brian", "Schultz"}); //Iterate over data and write to sheet Set<String> keyset = data.keySet(); int rownum = 0; for (String key : keyset) { Row row = sheet.createRow(rownum++); Object [] objArr = data.get(key); int cellnum = 0; for (Object obj : objArr) { Cell cell = row.createCell(cellnum++); if(obj instanceof String) cell.setCellValue((String)obj); else if(obj instanceof Integer) cell.setCellValue((Integer)obj); } } try { //Write the workbook in file system FileOutputStream out = new FileOutputStream(new File("howtodoinjava_demo.xlsx")); workbook.write(out); out.close(); System.out.println("howtodoinjava_demo.xlsx written successfully on disk."); } catch (Exception e) { e.printStackTrace(); } } }
Reading an Excel File
package com.howtodoinjava.demo.poi; //import statements public class ReadExcelDemo { public static void main(String[] args) { try { FileInputStream file = new FileInputStream(new File("howtodoinjava_demo.xlsx")); //Create Workbook instance holding reference to .xlsx file XSSFWorkbook workbook = new XSSFWorkbook(file); //Get first/desired sheet from the workbook XSSFSheet sheet = workbook.getSheetAt(0); //Iterate through each rows one by one Iterator<Row> rowIterator = sheet.iterator(); while (rowIterator.hasNext()) { Row row = rowIterator.next(); //For each row, iterate through all the columns Iterator<Cell> cellIterator = row.cellIterator(); while (cellIterator.hasNext()) { Cell cell = cellIterator.next(); //Check the cell type and format accordingly switch (cell.getCellType()) { case Cell.CELL_TYPE_NUMERIC: System.out.print(cell.getNumericCellValue() + "t"); break; case Cell.CELL_TYPE_STRING: System.out.print(cell.getStringCellValue() + "t"); break; } } System.out.println(""); } file.close(); } catch (Exception e) { e.printStackTrace(); } } }
References
https://howtodoinjava.com/java/library/readingwriting-excel-files-in-java-poi-tutorial/
https://www.baeldung.com/java-microsoft-excel