【Java】生成隨機的手機號碼並輸出到文件

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Random;
import java.util.Scanner;

public class Mobile {
    //中國移動
    public static final String[] CHINA_MOBILE = {
            "134", "135", "136", "137", "138", "139", "150", "151", "152", "157", "158", "159",
            "182", "183", "184", "187", "188", "178", "147", "172", "198"
    };
    //中國聯通
    public static final String[] CHINA_UNICOM = {
            "130", "131", "132", "145", "155", "156", "166", "171", "175", "176", "185", "186", "166"
    };
    //中國電信
    public static final String[] CHINA_TELECOME = {
            "133", "149", "153", "173", "177", "180", "181", "189", "199"
    };

    /**
     * 生成手機號
     *
     * @param op 0 移動 1 聯通 2 電信
     */
    public static String createMobile(int op) {
        StringBuilder sb = new StringBuilder();
        Random random = new Random();
        String mobile01;//手機號前三位
        int temp;
        switch (op) {
            case 0:
                mobile01 = CHINA_MOBILE[random.nextInt(CHINA_MOBILE.length)];
                break;
            case 1:
                mobile01 = CHINA_UNICOM[random.nextInt(CHINA_UNICOM.length)];
                break;
            case 2:
                mobile01 = CHINA_TELECOME[random.nextInt(CHINA_TELECOME.length)];
                break;
            default:
                mobile01 = "op標志位有誤！";
                break;
        }
        if (mobile01.length() > 3) {
            return mobile01;
        }
        sb.append(mobile01);
        //生成手機號后8位
        for (int i = 0; i < 8; i++) {
            temp = random.nextInt(10);
            sb.append(temp);
        }
        return sb.toString();
    }

    public static void main(String[] args) throws IOException {
        Scanner scan = new Scanner(System.in);
        System.out.println("請輸入生成的手機號個數：");
        int number = scan.nextInt();
        Random random = new Random();
        StringBuilder sb = new StringBuilder();
        for (int i = 1; i <= number; i++) {
            int op = random.nextInt(3);//隨機運營商標志位
            sb.append(createMobile(op));
            if (i % 10 == 0) {
                sb.append("\n");
            } else {
                sb.append("\t");
            }
        }
        //寫入文件
        FileOutputStream fos = new FileOutputStream(new File("F:/mobile.txt"));
        fos.write(sb.toString().getBytes());
        fos.close();

        System.out.println(number + "個號碼生成成功！");
    }
}