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

編碼時我們總會發(fā)現(xiàn)如下變量未被使用的警告提示：

上述代碼編譯通過且可以運行，但每行前面的“感嘆號”就嚴重阻礙了我們判斷該行是否設置的斷點了。這時我們可以在方法前添加?

@SuppressWarnings("unused")?去除這些“感嘆號”。

一.@SuppressWarings注解

作用：用于抑制編譯器產生警告信息。

示例1——抑制單類型的警告：

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

示例2——抑制多類型的警告：

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

示例3——抑制所有類型的警告：

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

二.注解目標

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通過?@SuppressWarnings?的源碼可知，其注解目標為類、字段、函數(shù)、函數(shù)入參、構造函數(shù)和函數(shù)的局部變量。

?而大家建議注解應聲明在最接近警告發(fā)生的位置。?

二.抑制警告的關鍵字

關鍵字	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

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• all?to suppress all warnings （抑制所有警告）
• boxing?to suppress warnings relative to boxing/unboxing operations（抑制裝箱、拆箱操作時候的警告）
• cast?to suppress warnings relative to cast operations （抑制映射相關的警告）
• dep-ann?to suppress warnings relative to deprecated annotation（抑制啟用注釋的警告）
• deprecation?to suppress warnings relative to deprecation（抑制過期方法警告）
• fallthrough?to suppress warnings relative to missing breaks in switch statements（抑制確在switch中缺失breaks的警告）
• finally?to suppress warnings relative to finally block that don’t return （抑制finally模塊沒有返回的警告）
• 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)(忽略沒有完整的switch語句)
• 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(忽略對null的操作)
• rawtypes?to suppress warnings relative to un-specific types when using generics on class params(使用generics時忽略沒有指定相應的類型)
• 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類中沒有聲明serialVersionUID變量)
• static-access?to suppress warnings relative to incorrect static access（抑制不正確的靜態(tài)訪問方式警告)
• synthetic-access?to suppress warnings relative to unoptimized access from inner classes（抑制子類沒有按最優(yōu)方法訪問內部類的警告）
• unchecked?to suppress warnings relative to unchecked operations（抑制沒有進行類型檢查操作的警告）
• unqualified-field-access?to suppress warnings relative to field access unqualified （抑制沒有權限訪問的域的警告）
• unused?to suppress warnings relative to unused code ?（抑制沒被使用過的代碼的警告）

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原文地址

轉載于:https://www.cnblogs.com/suruozhong/p/6264241.html

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