Java中的方法类| getExceptionTypes（）方法-yiteyi-C++库

这个 JAVA朗，反思方法getExceptionTypes（） “method class”的方法返回异常类型类对象的数组，这些对象声明由method对象抛出，以处理方法内部的异常。使用抛出子句的方法处理的所有异常，都将使用此方法作为类对象数组返回。如果应用此方法的方法在其throws子句中未声明任何异常，则此方法返回长度为0的数组。

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语法：

public Class<?>[] getExceptionTypes()

返回值： 此方法返回This method对象使用抛出子句声明的异常类的数组

下面的程序演示了method类的getExceptionTypes（）方法：

例1： 打印所有例外

                     /*                   
                     * Program Demonstrate getExceptionTypes() method                   
                     * of Method Class.                   
                     */                   
                     import                               java.lang.reflect.Method;                   
                             
                     public                               class                               GFG {                   
                             
                                         // Main method                   
                                         public                               static                               void                               main(String[] args)                   
                                         {                   
                                         try                               {                   
                                         // create class object                   
                                         Class classobj = demoClass.                               class                               ;                   
                             
                                         // get list of method Objects                   
                                         Method[] methods = classobj.getMethods();                   
                             
                                         // loop through list                   
                                         for                               (Method method : methods) {                   
                             
                                         // check for method with there name                   
                                         if                               (method.getName().equals(                               "setValue"                               )                   
                                         || method.getName().equals(                               "getValue"                               )) {                   
                                         // get Exception Types                   
                                         Class[] exceptions = method.getExceptionTypes();                   
                             
                                         // print exception Types thrown by method Object                   
                                         System.out.println(                               "Exception Thrown by Method: "                   
                                         + method.getName());                   
                                         System.out.println(                               "Exception Array length: "                   
                                         + exceptions.length);                   
                                         for                               (Class c : exceptions) {                   
                                         System.out.println(c.getName());                   
                                         }                   
                                         }                   
                                         }                   
                                         }                   
                                         catch                               (Exception e) {                   
                                         e.printStackTrace();                   
                                         }                   
                                         }                   
                     }                   
                     // a simple class                   
                     class                               demoClass {                   
                             
                                         // throw some exception by method                   
                                         public                               void                               setValue(String value)                   
                                         throws                               ClassNotFoundException,                   
                                         ArrayIndexOutOfBoundsException,                   
                                         ArithmeticException                   
                                         {                   
                                         }                   
                             
                                         // method throwing no exception                   
                                         public                               String getValue(String value)                   
                                         {                   
                                         return                               value;                   
                                         }                   
                     }                   

输出：

Exception Thrown by Method: getValue
Exception Array length: 0
Exception Thrown by Method: setValue
Exception Array length: 3
java.lang.ClassNotFoundException
java.lang.ArrayIndexOutOfBoundsException
java.lang.ArithmeticException

例2： 检查某个已定义的异常是否由方法对象引发。如果是，则打印true，否则打印false。

                     // Program Demonstrate getExceptionTypes() method                   
                     // Using getExceptionTypes() method of Method Class                   
                             
                     import                               java.lang.reflect.Method;                   
                             
                     // a simple class                   
                     class                               GFGSampleClass {                   
                             
                                         String value;                   
                             
                                         // throw some exception by method                   
                                         public                               void                               setValue(String value)                   
                                         throws                               ClassNotFoundException,                   
                                         ArrayIndexOutOfBoundsException,                   
                                         ArithmeticException                   
                                         {                   
                                         this                               .value = value;                   
                                         }                   
                     }                   
                             
                     public                               class                               GFG {                   
                             
                                         // Main method                   
                                         public                               static                               void                               main(String[] args)                   
                                         {                   
                                         try                               {                   
                                         // create class object                   
                                         Class classobj = GFGSampleClass.                               class                               ;                   
                             
                                         // get list of method Objects                   
                                         Method[] methods = classobj.getMethods();                   
                             
                                         // loop through list                   
                                         for                               (Method method : methods) {                   
                             
                                         // check for method with there name                   
                                         if                               (method.getName().equals(                               "setValue"                               )) {                   
                             
                                         // check whether method throw                   
                                         // IndexOutOfBoundsException Exception                   
                                         Class exceptionObj = IndexOutOfBoundsException.                               class                               ;                   
                                         boolean                               response = isCertainExceptionIsThrown(method,                   
                                         exceptionObj);                   
                                         System.out.println(                               "IndexOutOfBoundsException is "                   
                                         +                               "thrown by setValue(): "                               + response);                   
                                         }                   
                                         }                   
                                         }                   
                                         catch                               (Exception e) {                   
                                         e.printStackTrace();                   
                                         }                   
                                         }                   
                             
                                         /*                   
                                         * Return true if the given method throws the                   
                                         *     exception passed as Parameter.                   
                                         */                   
                                         private                               static                               boolean                   
                                         isCertainExceptionIsThrown(Method method, Class<?> exceptionName)                   
                                         {                   
                                         // get all exception list                   
                                         Class exceptions[] = method.getExceptionTypes();                   
                             
                                         for                               (                               int                               i =                               0                               ; i < exceptions.length; i++) {                   
                                         // check exception thrown or not                   
                                         if                               (exceptions[i] == exceptionName) {                   
                                         return                               true                               ;                   
                                         }                   
                                         }                   
                             
                                         return                               false                               ;                   
                                         }                   
                     }                   

输出：

IndexOutOfBoundsException is thrown by setValue(): false

参考： https://docs.oracle.com/javase/8/docs/api/java/lang/reflect/Method.html#getExceptionTypes–

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