Java 语法不会了,有关泛型的,求指教 - V2EX
rock_cloud

Java 语法不会了,有关泛型的,求指教

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  •   rock_cloud Mar 17, 2015 3128 views
    This topic created in 4098 days ago, the information mentioned may be changed or developed.
    下面的截图来自 org.apache.ibatis.session.defaults.DefaultSqlSession
    请问这里面的几个T的含义都是啥?没有见过泛型这么写的,比如T是Order订单类型,那这个函数应该怎么理解?
    5 replies    2015-03-17 19:00:34 +08:00
    msg7086
        1
    msg7086  
       Mar 17, 2015
    T就是某一个类型。至于具体是什么类型,则是根据调用时的类型来确定。
    rock_cloud
        2
    rock_cloud  
    OP
       Mar 17, 2015
    @msg7086 这个懂,不过<T> T放在一起,写在函数名前面是啥意思?
    sinsin
        3
    sinsin  
       Mar 17, 2015   1
    前 <T> 是声明泛型标识T
    后 T 是使用声明的这个标识作为返回类型
    rock_cloud
        4
    rock_cloud  
    OP
       Mar 17, 2015
    @sinsin this后面的<T>呢?
    sinsin
        5
    sinsin  
       Mar 17, 2015   1
    和List<T>那里类似,也是在使用这方法声明的T,是显式地使用。
    作为泛型实参用于和被调用的selectList方法那边的返回类型“匹配”
    和不写它(隐式使用),直接 this.selectList(...); 一个效果。。。
    (反正编译之后就没了
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