Java生成随机数列表

生成随机数列表

1、Java8以前

（1）Math.random

private List<UserEntity> random1() {
    ArrayList<UserEntity> list = Lists.newArrayList();
    for (int i = 1; i <= 10; i++)
        list.add(new UserEntity().setUserName("name" + (int) (Math.random() * 100) + 1));
    return list;
}

（2）Random类

private List<UserEntity> random2() {
    Random random = new Random();
    ArrayList<UserEntity> list = Lists.newArrayList();
    for (int i = 1; i <= 10; i++)
        list.add(new UserEntity().setUserName("name" + random.nextInt(100)));
    return list;
}

2、Java8以后（Stream）

private List<UserEntity> randomUserEntities() {
    return new Random()
        .ints(0, 100)
        .limit(10)
        .mapToObj(val -> new UserEntity().setUserName("name" + val))
        .collect(Collectors.toList());
}