去除编译警告@SuppressWarnings注解用法详解(转)

使用:
@SuppressWarnings(“”)
@SuppressWarnings({})
@SuppressWarnings(value={})

编码时我们总会发现如下变量未被使用的警告提示:

上述代码编译通过且可以运行,但每行前面的“感叹号”就严重阻碍了我们判断该行是否设置的断点了。这时我们可以在方法前添加 

@SuppressWarnings("unused") 去除这些“感叹号”。

一.@SuppressWarings注解

作用:用于抑制编译器产生警告信息。

示例1——抑制单类型的警告:

 

@SuppressWarnings("unchecked")
public void addItems(String item){
  @SuppressWarnings("rawtypes")
   List items = new ArrayList();
   items.add(item);
}

示例2——抑制多类型的警告:

 

 

@SuppressWarnings(value={"unchecked", "rawtypes"})
public void addItems(String item){
   List items = new ArrayList();
   items.add(item);
}

示例3——抑制所有类型的警告:

@SuppressWarnings("all")
public void addItems(String item){
   List items = new ArrayList();
   items.add(item);
}

二.注解目标

 

通过 @SuppressWarnings 的源码可知,其注解目标为类、字段、函数、函数入参、构造函数和函数的局部变量。

 而大家建议注解应声明在最接近警告发生的位置。 

二.抑制警告的关键字

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 to 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

 

  • all to suppress all warnings (抑制所有警告)
  • boxing to suppress warnings relative to boxing/unboxing operations(抑制装箱、拆箱操作时候的警告)
  • cast to suppress warnings relative to cast operations (抑制映射相关的警告)
  • dep-ann to suppress warnings relative to deprecated annotation(抑制启用注释的警告)
  • deprecation to suppress warnings relative to deprecation(抑制过期方法警告)
  • fallthrough to suppress warnings relative to missing breaks in switch statements(抑制确在switch中缺失breaks的警告)
  • finally to suppress warnings relative to finally block that don’t return (抑制finally模块没有返回的警告)
  • 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)(忽略没有完整的switch语句)
  • nls to suppress warnings relative to non-nls string literals(忽略非nls格式的字符)
  • null to suppress warnings relative to null analysis(忽略对null的操作)
  • rawtypes to suppress warnings relative to un-specific types when using generics on class params(使用generics时忽略没有指定相应的类型)
  • 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(忽略在serializable类中没有声明serialVersionUID变量)
  • static-access to suppress warnings relative to incorrect static access(抑制不正确的静态访问方式警告)
  • synthetic-access to suppress warnings relative to unoptimized access from inner classes(抑制子类没有按最优方法访问内部类的警告)
  • unchecked to suppress warnings relative to unchecked operations(抑制没有进行类型检查操作的警告)
  • unqualified-field-access to suppress warnings relative to field access unqualified (抑制没有权限访问的域的警告)
  • unused to suppress warnings relative to unused code  (抑制没被使用过的代码的警告)

 

原文地址

posted @ 2017-01-09 10:25  suruozhong  阅读(828)  评论(0编辑  收藏  举报