1.     通过Collection执行的所有操作也是可以通过set和list执行的<br />       <br />       Collection操作方法图：<br />![image.png](https://cdn.nlark.com/yuque/0/2021/png/12862216/1619094958665-bee59ce4-6ed6-4769-8877-1539e4fbb8a5.png#clientId=ua32b5731-b1cb-4&from=paste&height=380&id=uee9070ac&margin=%5Bobject%20Object%5D&name=image.png&originHeight=745&originWidth=1556&originalType=binary&size=429304&status=done&style=none&taskId=ub087022f-7eb4-49ef-b56e-285f8e20ab0&width=794)