异常The operator != is undefined for the argument type(s) long, null

错误The operator != is undefined for the argument type(s) long, null

此处报错 if (users.getUsersid() != null)
The operator != is undefined for the argument type(s) long, null

通过Ctrl+左键找到错误源
private long usersid;
public long getUsersid() {
return this.usersid;
}
应该是Long
改正之后
private Long usersid;
public Long getUsersid() {
return this.usersid;
}