运算符优先级
Java 语言中运算符的优先级共分为 14 级，其中 1 级最高，14 级最低。在同一个表达式中运算符优先级高的先执行。
级数 运算符                                                  结合优先级顺序
1   ()、[]                                          从左向右
2   !、+、-、~、++、–                                 从右向左
3   *、/、%                                          从左向右
4   +、-                                            从左向右
5   <<、>>、>>>                                      从左向右
6   <、<=、>、>=、instanceof                         从左向右
7   ==、!=                                          从左向右
8   &                                               从左向右
9   ^                                               从左向右
10  |                                              从左向右
11  &&                                             从左向右
12  ||                                             从左向右
13  ?:                                             从右向左
14  =、+=、-=、*=、/=、&=、\=、^=、~=、«=、»=、>>>=    从右向左