@SuppressWarnings注解

    今天看到小哥哥在我的代码里加了@SuppressWarnings("rawtypes")遂有些好奇（这个鬼东西是干吗用的啊），于是在网上问了一下度娘，娘说：

1.SuppressWarnings来源？

   java.lang.SuppressWarnings是J2SE5.0中标准的Annotation之一。

2.SuppressWarnings用来干什么？

     用于抑制编译器产生警告信息。

3.SuppressWarnings用在哪儿？

     @SuppressWarnings("***")可标注在类、字段、方法、参数、构造方法，以及局部变量上。

4.SuppressWarnings可以抑制哪些警告？

关键字	用途
all	to suppress all warnings
boxing	to suppress warnings relative to boxing/unboxing operations
cast	to suppress warnings relative to cast operations
dep-ann	to suppress warnings relative to deprecated annotation
deprecation	to suppress warnings relative to deprecation
fallthrough	to suppress warnings relative to missing breaks in switch statements
finally	to suppress warnings relative to finally block that don’t return
hiding	to suppress warnings relative to locals that hide variable
incomplete-switch	to suppress warnings relative to missing entries in a switch statement (enum case)
nls	to suppress warnings relative to non-nls string literals
null	to suppress warnings relative to null analysis
rawtypes	to suppress warnings relative to un-specific types when using generics on class params
restriction	to suppress warnings relative to usage of discouraged or forbidden references
serial	to suppress warnings relative to missing serialVersionUID field for a serializable class
static-access	o suppress warnings relative to incorrect static access
synthetic-access	to suppress warnings relative to unoptimized access from inner classes
unchecked	to suppress warnings relative to unchecked operations
unqualified-field-access	to suppress warnings relative to field access unqualified
unused	to suppress warnings relative to unused code

5.SuppressWarnings有哪些写法？

    SuppressWarnings("***")抑制单一类型警告

    SuppressWarnings(value={"***","***"})抑制多类型警告

6.SuppressWarnings示例

       @SuppressWarnings("rawtypes") ，rawtypes是说传参时也要传递带泛型的参数。      

        @SuppressWarnings("unchecked") ，告诉编译器忽略 unchecked 警告信息，如使用List，ArrayList等未进行参数化产生的警告信息。   

         @SuppressWarnings("unused") ,告诉编译器忽略未使用变量的警告信息。