Java方法定义问题

Question

该方法定义如下：

public static void checkNotNull<T extends Throwable>(Object value, String name, Class<T> exceptionClass) 
{

}

然后编译器抛出一些错误：

**此行有多个标记

- void is an invalid type for the variable checkNotNull
- Duplicate field ValidationUtility.value
- Syntax error on token ">", Identifier expected after this token
- The type Class is not generic; it cannot be parameterized with 
 arguments <T>
- The type Class is not visible
- Duplicate field ValidationUtility.exceptionClass
- T cannot be resolved to a type
- Syntax error, insert ";" to complete FieldDeclaration
- Duplicate field ValidationUtility.String**

有什么不对吗？请帮帮我，谢谢。

Answer 1

void checkNotNull<T extends Throwable>(...,Class<T> exceptionClass)语法错误。它应该是<T extends Throwable>void checkNotNull(...,Class<T> exceptionClass)

public static <T extends Throwable> void checkNotNull(Object value, String name, 
                                                      Class<T> exceptionClass) {}

Answer 2

在void之前声明<T extends Throwable>。

public static <T extends Throwable> void checkNotNull(Object value, String name,
Class<T> exceptionClass) {}

您可以参考Generics Tutorial

JLS#8.4. Method Declarations

MethodHeader:
     MethodModifiersopt TypeParametersopt Result MethodDeclarator Throwsopt

Answer 3

public static <T extends Throwable> void checkNotNull(Object value, String name, Class<T> exceptionClass) 
{

}