我如何使用Apache POI在Excel中增加行

Question

我正在編寫一個程序，以使用java和apache poi來記錄Excel表格來跟蹤員工的座位。 該程序將提示用戶輸入辦公桌編號，員工姓名和坐在該辦公桌上的員工人數。 我的問題是，該程序僅寫入用戶輸入的最后信息，從而刪除了先前在該行中輸入的信息。 如何保留Excel工作表第一行中輸入的內容？ 我將其設置在一個循環中，在該循環中，將一直提示用戶輸入座位信息，直到用戶輸入EXIT。 我希望每次輸入新信息時它都會向下遞增。

這是我到目前為止的內容：

import java.util.*;
import org.apache.poi.hssf.usermodel.*;
import org.apache.poi.hssf.util.*; 
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.util.*;
import java.io.*;

public class EmployeeSeatingRep {

public static void main(String[] args){

    String deskNumber = "";
    String employeeName = "";
    int empsAtDesk = 0;
    boolean keepRunning = true;


//Blank workbook
    HSSFWorkbook workbook = new HSSFWorkbook();
//Blank sheet
    HSSFSheet sheet = workbook.createSheet("Seating Details");

//create heading

        Row rowHeading = sheet.createRow(0);
        rowHeading.createCell(0).setCellValue("Desk:");
        rowHeading.createCell(1).setCellValue("Employee(s)Name:");
        rowHeading.createCell(2).setCellValue("Number At Desk:");

//Font size and style loop for my headers

        for(int i = 0; i < 3; i++)
        {
            CellStyle stylerowHeading = workbook.createCellStyle();
            Font font = workbook.createFont();
            font.setBold(true);
            font.setFontName(HSSFFont.FONT_ARIAL);
            font.setFontHeightInPoints((short) 11);
            stylerowHeading.setFont(font);
            stylerowHeading.setVerticalAlignment(CellStyle.ALIGN_CENTER);
            rowHeading.getCell(i).setCellStyle(stylerowHeading);
        }
    while(keepRunning){
        Scanner scnr = new Scanner(System.in);

        System.out.print("Enter desk number: ");
        deskNumber = scnr.nextLine();
        if(deskNumber.equals("EXIT"))
        {
            System.out.print("You have ended the program");
            System.exit(0);
        }
        else
        {
            System.out.print("Enter employee name: ");
            employeeName = scnr.nextLine();
            System.out.print("Enter amount of employees at desk: ");
            empsAtDesk = scnr.nextInt();







//This data needs to be written (Object[])
        Map <String, Object[]> data = new TreeMap<String, Object[]>();
        data.put("2", new Object[] {deskNumber, employeeName, empsAtDesk});

//Iterate over data and write to sheet
        Set<String> keyset = data.keySet();
        int rownum = 1;
        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);
                }
            }
            if(!(deskNumber.equals("EXIT")))
            {
                rownum++;

        }

//Auto size my columns that will be filled out with user input info.            
        for (int i = 0; i < 3; i++)
        {
            sheet.autoSizeColumn(i);
        }
        }
try{

 //save to excel file
        FileOutputStream out = new FileOutputStream(new File("Employee Seating Report.xls"));
        workbook.write(out);
        out.flush();
        out.close();
        System.out.println("Excel Written Succesfully...");
    } catch (FileNotFoundException e) {

        e.printStackTrace();

    } catch (IOException e){

        e.printStackTrace();

    } catch (Exception e) {

        System.out.println(e.getMessage());
    }
  } 
}       
}//pub static void end brace    
}//pub class end brace

Answer 1

您正在描述的問題是由以下原因引起的：

int rownum = 1; <--
for(String Key : keyset)
{
    Row row = sheet.createRow(rownum++);

您已經在主循環中聲明了rownum ，因此，它將始終為1。

如果不使用循環來構建，填充和寫入data映射，而是使用循環來構建行對象List ，然后在用戶完成操作后將其寫入文件，則可以大大簡化操作。

Answer 2

用戶輸入的每個信息都應添加到excel中的新行中，因此您需要在for循環外創建一行，並且僅在for循環中為輸入的數據創建單元格。 像這樣：

    Scanner scnr = new Scanner(System.in);

    System.out.print("Enter desk number: ");
    deskNumber = scnr.nextLine();
    if(deskNumber.equals("EXIT"))
    {
        System.out.print("You have ended the program");
        System.exit(0);
    }
    else
    {
        System.out.print("Enter employee name: ");
        employeeName = scnr.nextLine();
        System.out.print("Enter amount of employees at desk: ");
        empsAtDesk = scnr.nextInt(); scnr.next();
        Row row = sheet.createRow(rownum++);
        Object [] objArr = new Object[] {deskNumber, employeeName, empsAtDesk};
        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);
            }
        }
  }

希望這可以幫助。