抱歉,我理解有误。以下是一种生成不重复的方案:
private static final String TASK_ID_PREFIX = "U00000000430138013002023032809110096f5bb04e024";
Set taskIdSet = new HashSet<>();
String taskId;
while(taskIdSet.size() < 1000000){
String seqNo = String.format("%06d", (int)(Math.random() * 1000000 + 1));
taskId = TASK_ID_PREFIX + seqNo;
taskIdSet.add(taskId);
// do something with taskId
}