import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class WriteToExcel {

    public static void main(String[] args) throws IOException {
        // 创建工作簿
        Workbook workbook = new XSSFWorkbook();
        // 创建一个新的工作表
        Sheet sheet = workbook.createSheet("Data");

        // 创建数据
        List<List<Object>> data = new ArrayList<>();
        data.add(Arrays.asList("Name", "Age", "City"));
        data.add(Arrays.asList("John", 30, "New York"));
        data.add(Arrays.asList("Alice", 25, "London"));

        // 写入数据
        writeData(sheet, data, 0, 0);

        // 创建另一个数据集合
        List<List<Object>> anotherData = new ArrayList<>();
        anotherData.add(Arrays.asList("ID", "Product", "Price"));
        anotherData.add(Arrays.asList(1, "Laptop", 1200));
        anotherData.add(Arrays.asList(2, "Phone", 800));

        // 写入另一个数据集合
        writeData(sheet, anotherData, 0, 4);

        // 保存工作簿到文件
        try (FileOutputStream fileOut = new FileOutputStream("data.xlsx")) {
            workbook.write(fileOut);
        }

        // 关闭工作簿
        workbook.close();
    }

    // 写入数据到工作表
    private static void writeData(Sheet sheet, List<List<Object>> data, int startRow, int startColumn) {
        for (int i = 0; i < data.size(); i++) {
            Row row = sheet.getRow(i + startRow);
            if (row == null) {
                row = sheet.createRow(i + startRow);
            }
            List<Object> rowData = data.get(i);
            for (int j = 0; j < rowData.size(); j++) {
                Cell cell = row.getCell(j + startColumn);
                if (cell == null) {
                    cell = row.createCell(j + startColumn);
                }
                cell.setCellValue(rowData.get(j).toString());
            }
        }
    }
}