POIでExcelのセルの書式を金額型にする

poi_excel_jpy_format.kt

import org.apache.poi.ss.usermodel.WorkbookFactory
import org.apache.poi.xssf.usermodel.XSSFWorkbook
import java.io.FileInputStream
import java.io.FileOutputStream

fun main(args: Array<String>) {
    val path = "test.xlsx"
    write(path)
    read(path)
}

fun write(path: String) {
    val wb = XSSFWorkbook();
    val format = wb.createDataFormat();
    val sheet = wb.createSheet();
    val row = sheet.createRow(0);

    val cell = row.createCell(0);
    val style = wb.createCellStyle();
    style.dataFormat = format.getFormat("\"￥\"#,##0");
    cell.cellStyle = style;
    cell.setCellValue(12345.toDouble()) // Stringとして入れると、フォーマットが効かない (例: "12345")

    val output = FileOutputStream(path)
    wb.write(output)
}

fun read(path: String) {
    val input = FileInputStream(path)
    val wb = WorkbookFactory.create(input)

    val sheet = wb.getSheetAt(0)
    val row = sheet.getRow(0)
    val cell = row.getCell(0)
    println(cell.numericCellValue.toInt())
}