消除强制类型转换警告的最优雅的方式是什么? - V2EX
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7911364440
V2EX    Java

消除强制类型转换警告的最优雅的方式是什么?

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  •   7911364440 Jul 22, 2022 2368 views
    This topic created in 1385 days ago, the information mentioned may be changed or developed.
    类似`(List<String>) obj`这样的代码编译器会提示`Unchecked cast: 'java.lang.Object' to 'java.util.List<java.lang.String>'`这样的警告,看着很难受。
    在网上搜了下几乎千篇一律都是使用`@SuppressWarnings("unchecked")`忽略警告,想问一下有没有更优雅的处理方式?
    6 replies    2022-07-22 18:29:05 +08:00
    Saxton
        1
    Saxton  
       Jul 22, 2022
    new 一个新的 list ,手动 add 过去( doge
    zed1018
        2
    zed1018  
       Jul 22, 2022
    objectMapper.convert(from, type) ?
    AoEiuV020CN
        3
    AoEiuV020CN  
       Jul 22, 2022
    眼不见为净,封装一个工具类,工具类里 SuppressWarnings ,外面调用就没有警告也不用忽略警告了,
    siweipancc
        4
    siweipancc  
       Jul 22, 2022 via iPhone
    List<?> 即可,下边 toString
    nothingistrue
        5
    nothingistrue  
       Jul 22, 2022
    这个警告的原因,不是强制类型转换,而是 List 到 List<String> 加泛型。

    如果你需要的是 List 而不是 List<String> 那么用 List<?> 或 List<Object> 代替 List<String>。

    如果你需要的就是 List<String> ,并且确定返回的就是 List<String>,那么 @SuppressWarnings("unchecked") 就是最优解。

    如果你不能 100% 确定返回的是 List<String>,那么还得用 List<?> 或 List<Object> 接受变量,然后 if (get(i) instanceof String){...} else {...}
    wolfie
        6
    wolfie  
       Jul 22, 2022
    public static <T> T cast(Object object) {
    return (T)object;
    }
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