在开发中，有时候IDE/编译器会给出一些没有必要的告警。可以通过@SuppressWarnings来屏蔽。@SuppressWarnings有很多种面向场景，下面一一列出：

• 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