Apache POI (Poor Obfuscation Implementation File System)

Prerequisite
Download all poi jar files
https://poi.apache.org/download.html

1.  Terms
   • Workbook – The file contains number of sheets
   • Sheet – Matrix contains rows and cell
   • Row – Record of an entity in one row
   • Cell – A single cell which hold value

2. JFileChooser fileChooser = new JFileChooser();
           int returnValue = fileChooser.showDialog(null, "Select File");
           
           if(returnValue == JFileChooser.APPROVE_OPTION) {
               Workbook workbook = new HSSFWorkbook(new FileInputStream(fileChooser.getSelectedFile()));
               
               Sheet sheet = workbook.getSheetAt(0);
               
               for(Iterator<Row> rit = sheet.rowIterator(); rit.hasNext();){
                   for(Iterator<Cell> cit = rit.next().cellIterator(); cit.hasNext();){
                       System.out.println(cit.next());
                   }
                   System.out.println("");
               }
           } else {
               System.out.println("Invalid output");
           }

3. JFileChooser fileChooser = new JFileChooser();
           int returnValue = fileChooser.showDialog(null, "Select File");
           
           if(returnValue == JFileChooser.APPROVE_OPTION) {
               FileInputStream excelFile = new FileInputStream(fileChooser.getSelectedFile());
               Workbook workbook = new XSSFWorkbook(excelFile);
               
               Sheet sheet = workbook.getSheetAt(0);
               
               for(Iterator<Row> rit = sheet.rowIterator(); rit.hasNext();) {
                   for(Iterator<Cell> cit = rit.next().cellIterator(); cit.hasNext();) {
                       System.out.print(cit.next() + "\t" + cit.next());
                   }
                   System.out.println("");
               }
           }

4.  Workbook workbook = new HSSFWorkbook();
           
           Sheet sheet1 = workbook.createSheet("movies");
   //        Sheet sheet2 = workbook.createSheet("Test Cases");
   //        Sheet sheet3 = workbook.createSheet(WorkbookUtil.createSafeSheetName("$*(^&?"));
           
           Row row = sheet1.createRow(0);
           
   //        Cell cell = row.createCell(4);
   //        cell.setCellValue("Hello World");
   //        Cell cell2 = row.createCell(3);
   //        cell2.setCellValue("terminator");
   //        System.out.println(cell.getRichStringCellValue().toString());
   //        System.out.println(cell2.getRichStringCellValue().toString());
   
           Cell cell1 = row.createCell(0);
           Cell cell2 = row.createCell(1);
           Cell cell3 = row.createCell(2);
           Cell cell4 = row.createCell(3);
           Cell cell5 = row.createCell(4);
           
           cell1.setCellValue(5);
           cell2.setCellValue("+");
           cell3.setCellValue(6);
           cell4.setCellValue("=");
           cell5.setCellFormula("A1+C1");
           
           try {
               FileOutputStream outputStream = new FileOutputStream("test1.xlsx");
               workbook.write(outputStream);
               outputStream.close();
           } catch (Exception e) {
               e.printStackTrace();
           }

5.  Complete Program

   import java.io.FileInputStream;
   import java.io.FileNotFoundException;
   import java.io.FileOutputStream;
   import java.io.IOException;
   import java.util.Iterator;
   import javax.swing.JFileChooser;
   import org.apache.poi.hssf.usermodel.HSSFWorkbook;
   import org.apache.poi.ss.usermodel.Workbook;
   import org.apache.poi.ss.usermodel.Sheet;
   import org.apache.poi.ss.util.WorkbookUtil;
   import org.apache.poi.ss.usermodel.Row;
   import org.apache.poi.ss.usermodel.Cell;
   import org.apache.poi.xssf.usermodel.XSSFWorkbook;
   
   /**
    *
    * @author Shailesh Sonare
    */
   public class ApachePOIDemo {
   
       /**
        * @param args the command line arguments
        */
       public static void main(String[] shailesh) throws IOException {
           
           /*
           
           Workbook workbook = new HSSFWorkbook();
           
           Sheet sheet1 = workbook.createSheet("movies");
   //        Sheet sheet2 = workbook.createSheet("Test Cases");
   //        Sheet sheet3 = workbook.createSheet(WorkbookUtil.createSafeSheetName("$*(^&?"));
           
           Row row = sheet1.createRow(0);
           
   //        Cell cell = row.createCell(4);
   //        cell.setCellValue("Hello World");
   //        Cell cell2 = row.createCell(3);
   //        cell2.setCellValue("terminator");
   //        System.out.println(cell.getRichStringCellValue().toString());
   //        System.out.println(cell2.getRichStringCellValue().toString());
   
           Cell cell1 = row.createCell(0);
           Cell cell2 = row.createCell(1);
           Cell cell3 = row.createCell(2);
           Cell cell4 = row.createCell(3);
           Cell cell5 = row.createCell(4);
           
           cell1.setCellValue(5);
           cell2.setCellValue("+");
           cell3.setCellValue(6);
           cell4.setCellValue("=");
           cell5.setCellFormula("A1+C1");
           
           try {
               FileOutputStream outputStream = new FileOutputStream("test1.xlsx");
               workbook.write(outputStream);
               outputStream.close();
           } catch (Exception e) {
               e.printStackTrace();
           }
           */
           /*
           JFileChooser fileChooser = new JFileChooser();
           int returnValue = fileChooser.showDialog(null, "Select File");
           
           if(returnValue == JFileChooser.APPROVE_OPTION) {
               Workbook workbook = new HSSFWorkbook(new FileInputStream(fileChooser.getSelectedFile()));
               
               Sheet sheet = workbook.getSheetAt(0);
               
               for(Iterator<Row> rit = sheet.rowIterator(); rit.hasNext();){
                   for(Iterator<Cell> cit = rit.next().cellIterator(); cit.hasNext();){
                       System.out.println(cit.next());
                   }
                   System.out.println("");
               }
           } else {
               System.out.println("Invalid output");
           }
           */
           
           JFileChooser fileChooser = new JFileChooser();
           int returnValue = fileChooser.showDialog(null, "Select File");
           
           if(returnValue == JFileChooser.APPROVE_OPTION) {
               FileInputStream excelFile = new FileInputStream(fileChooser.getSelectedFile());
               Workbook workbook = new XSSFWorkbook(excelFile);
               
               Sheet sheet = workbook.getSheetAt(0);
               
               for(Iterator<Row> rit = sheet.rowIterator(); rit.hasNext();) {
                   for(Iterator<Cell> cit = rit.next().cellIterator(); cit.hasNext();) {
                       System.out.print(cit.next() + "\t" + cit.next());
                   }
                   System.out.println("");
               }
           }
           
       }    
   }