问使用java应用程序运行后台进程

EN

import java.time.LocalDateTime;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;

public class VoucherManager {
    private static double newVoucher = 2500.00;
    private Map<String, Double> employeeVoucher = new TreeMap<>();
    private  LocalDateTime now = LocalDateTime.now();

    public static VoucherManager getInstance() {
        return new VoucherManager();
    }
    public void incrementVoucher() {
        employeeVoucher.put("Olatunji Oniyide", 200.00);
        employeeVoucher.put("Andrew Mbata", 500.00);
        employeeVoucher.put("Opeyemi Oniyide", 700.00);

        Set<Map.Entry<String, Double>> set = employeeVoucher.entrySet();
        int day = now.getDayOfMonth();
        if((day == 1) || (day == 2)) {
            for(Map.Entry<String, Double> map : set)
               System.out.println(map.getKey() + ":" + (map.getValue() + newVoucher));
        } else {
            throw new AssertionError();
        }
    }

    public static void main(String[] args) {
        VoucherManager voucher = VoucherManager.getInstance();
        voucher.incrementVoucher();
    }
    }