list.foreach用法

java forEach循环list、获取list中的指定数据

IPage<SysUser> pageList = sysUserService.page(page, queryWrapper);pageList.getRecords().forEach(sysUser -> {
   QueryWrapper<SysRole> roleWrapper = new QueryWrapper<>();
   roleWrapper.nested(i -> i.inSql("id", String.format("select role_id from sys_user_role where user_id='%s'", sysUser.getId())));
   List<SysRole> roleList = sysRoleService.list(roleWrapper);
   List<String> roleIdList = roleList.stream().map(SysRole::getId).collect(Collectors.toList());
   List<String> roleNames = roleList.stream().map(SysRole::getRoleName).collect(Collectors.toList());
   sysUser.setUserRoleNames(CollectionUtil.join(roleNames, ","));
   sysUser.setUserRoleIdList(roleIdList);
});

Map遍历：

public static Map<String, Object> transform(Map<String, Object> result) {
    result.forEach((key, value) -> {
        if (value instanceof LocalDateTime) {
            result.put(key, ((LocalDateTime) value)
                    .format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
        } else if (value instanceof LocalDate) {
            result.put(key, ((LocalDate) value)
                    .format(DateTimeFormatter.ofPattern("yyyy-MM-dd")));
        } else if (value instanceof Long) {
            result.put(key, String.valueOf(value));
        }
    });
    return result;
}

List<Map>变例

List<Map> mapList = JSONArray.parseArray(str,Map.class);

mapList.forEach(map1 -> { map1.forEach((k,v) -> { System.out.println(v); }); });

例子

public static void main(String[] args) {
    //使用com.google.guava包创建集合
    List <String> list = Lists.newArrayList("1", "2", "3", "4");
    //1、正常遍历
    list.forEach(item -> System.out.println(item));
    //2、根据条件遍历
    list.forEach(item -> {
        if ("2".equals(item)) {
            System.out.println(item);

        }
    });
 

最后

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