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1、@Override 強制檢查子類的方法重寫
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java 代碼
package?com.test; ????public?class?OverrideTest?{ ?????? ??????@Override??????public?String?toString() ??????{ ??????????return?"This?is?override"; ??????} ????????public?static?void?main(String[]?args)?{ ?????????? ??????????OverrideTest?ot?=?new?OverrideTest(); ??????????System.out.println(ot.toString()); ??????} ????}?? ?
如下如果不小心把toString()寫成了ToString()，則會通不過編譯
java 代碼
package?com.test; ????public?class?OverrideTest?{ ?????? ??????@Override??????public?String?ToString() ??????{ ??????????return?"This?is?override"; ??????} ????????public?static?void?main(String[]?args)?{ ?????????? ??????????OverrideTest?ot?=?new?OverrideTest(); ??????????System.out.println(ot.toString()); ??????} ????} ?? ?
2、@Deprecated 過時的，不建議被使用的
java 代碼
package?com.test; ????import?java.util.Date; ????public?class?DeprecatedTest?{ ????????@Deprecated??????public?void?doSomething() ??????{ ??????????System.out.println("do?something"); ??????} ??????public?static?void?main(String[]?args)?{ ??????????DeprecatedTest?dt?=?new?DeprecatedTest(); ??????????dt.doSomething(); ??????????Date?date?=?new?Date(); ??????????date.toLocaleString(); ??????} ????} ?? 此時，第１４行和第１６行都會被劃上線條，表示doSomething方法和toLocalString方法不建議被使用?。并且第16行前端有個警告符號。過時的或不建議被使用的方法被調用時是否出現警告，需要在IDE中設置:
window->preferences->java->compiler->Errors/Warnings->Deprecated and restricted API
將其中的兩個復選框選中即可。
java 代碼
package?com.test; ????public?class?SubDeprecatedTest?extends?DeprecatedTest?{ ????????@Override??????public?void?doSomething() ??????{ ??????????System.out.println("do?something?in?subscribe?class"); ??????} ??????public?static?void?main(String[]?args)?{ ??????????SubDeprecatedTest?sdt?=?new?SubDeprecatedTest(); ??????????sdt.doSomething(); ??????} ????} ?? 其中第6行出現警告符號
3、@SuppressWarnings 壓制某些不必要的警告，壓制一個或多個警告
語法: @SuppressWarnings("unchecked") 或者 @SuppressWarnings ({"unchecked","deprecation"})
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java 代碼
package?com.test; ????import?java.util.Date; ??import?java.util.Map; ??import?java.util.TreeMap; ????public?class?SuppressWarningsTest?{ ????????@SuppressWarnings("unchecked") ??????public?static?void?main(String[]?args)?{ ????????????????????Map?map?=?new?TreeMap(); ??????????map.put("hello",?new?Date()); ?????????? ??????????System.out.println(map.get("hello")); ??????} ????} ?? ?
java 代碼
package?com.test; ????import?java.util.Date; ??import?java.util.Map; ??import?java.util.TreeMap; ????public?class?SuppressWarningsTest?{ ????????@SuppressWarnings({"unchecked","deprecation"}) ??????public?static?void?main(String[]?args)?{ ????????????????????Map?map?=?new?TreeMap(); ??????????map.put("hello",?new?Date()); ?????????? ??????????System.out.println(map.get("hello")); ????????????????????DeprecatedTest?dt?=?new?DeprecatedTest(); ??????????dt.doSomething(); ??????} ????} ??
轉載于:https://www.cnblogs.com/xingmeng/archive/2012/05/30/2526026.html
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