java:exception

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--- java:exception [2014/01/22 12:58]
kwon37xi 새로 만듦
+++ java:exception [2014/01/22 13:20]
kwon37xi [Checked Exception]
@@ 줄 3: / 줄 3: @@
 ===== Checked Exception =====
 가능하면 사용하지 말 것.
-  * [[http://java.dzone.com/articles/throwing-undeclared-checked|Throwing Undeclared Checked Exceptions | Javalobby]]<code java>
+  * [[http://java.dzone.com/articles/throwing-undeclared-checked|Throwing Undeclared Checked Exceptions | Javalobby]]
-class Thrower {
+  * [[http://www.gamlor.info/wordpress/?p=1020|Throwing Checked Exceptions Like Unchecked Exceptions in Java | Gamlor]]<code java>
-    public static void spit(final Throwable exception) {
+public class ExceptionThrower {
-        class EvilThrower<T extends Throwable> {
+    private ExceptionThrower() {}
-            @SuppressWarnings("unchecked")
-            private void sneakyThrow(Throwable exception) throws T {
+    public static void spit(final Throwable throwable) {
-                throw (T) exception;
+        // 아래 <RuntimeException> 타입 정보는 컴파일 상태에서는 지워진다.
-            }
+        ExceptionThrower.<RuntimeException>throwWithoutCheck(throwable);
-        }
+    }
-        new EvilThrower().sneakyThrow(exception);
+    @SuppressWarnings("unchecked")
+    private static <T extends Throwable> void throwWithoutCheck(Throwable throwable) throws T {
+        // 아래 Type Casting 정보는 Java Generic의 특성상 컴파일시 정보가 사라지므로
+        // 실제 캐스팅은 발생하지 않는다.
+        throw (T) throwable;
     }
 }
-public class ThrowerSample {
+public final class UncheckedThrow {
-    public static void main( String[] args ) {
+    private UncheckedThrow(){}
-        Thrower.spit(new RemoteException("go unchecked!"));
+    public static void throwUnchecked(final Exception ex){
+        // Now we use the 'generic' method. Normally the type T is inferred
+        // from the parameters. However you can specify the type also explicit!
+        // Now we du just that! We use the RuntimeException as type!
+        // That means the throwsUnchecked throws an unchecked exception!
+        // Since the types are erased, no type-information is there to prevent this!
+        UncheckedThrow.<RuntimeException>throwsUnchecked(ex);
+    }
+    /**
+     * Remember, Generics are erased in Java. So this basically throws an Exception. The real
+     * Type of T is lost during the compilation
+     */
+    public static <T extends Exception> void throwsUnchecked(Exception toThrow) throws T{
+        // Since the type is erased, this cast actually does nothing!!!
+        // we can throw any exception
+        throw (T) toThrow;
     }
 }
 </code>
-  * [[http://www.gamlor.info/wordpress/?p=1020|Throwing Checked Exceptions Like Unchecked Exceptions in Java | Gamlor]]

java/exception.txt · 마지막으로 수정됨: 2021/07/14 12:49 저자 kwon37xi