The getGenericExceptionTypes() method of java.lang.reflectMethod class returns an array of Type objects representing Exceptions thrown by the method object to handle exception. All the exceptions handled by method using thrown clause are returned as array of Type objects using this method. This method returns an array of length 0, if the method, on which this method is applied, declares no exceptions in its throws clause. Example:
Code:
public class demo{
public void setValue(String value)
throws ClassNotFoundException, ArrayIndexOutOfBoundsException,
ArithmeticException {}
}
Explanation:
In the above method when we going to apply getGenericExceptionTypes() method
it is going to return array of the exception types.
Array = {
java.lang.ClassNotFoundException,
java.lang.ArrayIndexOutOfBoundsException,
java.lang.ArithmeticException,
}
Syntax:
public Type[] getGenericExceptionTypes()
Return Value: It returns an array of the exception types thrown by the this Method object Exception: This method throws following exceptions:
- GenericSignatureFormatError – if the generic method signature is not same as the format specified in The JVM Specification.
- TypeNotPresentException – if Exception Types specified by throws clause refers to a non-existent type declaration.
- MalformedParameterizedTypeException – if the underlying executable’s throws clause refers to a parameterized type that cannot be instantiated for any reason.
Below programs illustrates getGenericExceptionTypes() method of Method class: Program 1: Print all Exception Types thrown by a Method with the help of getGenericExceptionTypes()
Java
/** Program Demonstrate how to apply* getGenericExceptionTypes() method*/import java.lang.reflect.Method;import java.lang.reflect.Type;public class GFG { // Main method public static void main(String[] args) { try { // create class object Class classobj = demoClass.class; // create parameter type of string Class[] parameterTypes = { String.class }; // get list of method objects Method[] methods = classobj.getMethods(); // loop through all methods for (Method m : methods) { if (m.getName().equals("setValue") || m.getName().equals("getValue")) { // apply getGenericExceptionTypes() method Type[] genericExceptions = m.getGenericExceptionTypes(); // print exception Types thrown by method Object System.out.println("Generic Exception Thrown by Method: " + m.getName()); System.out.println("Generic Exception Type Array length: " + genericExceptions.length); // If method has Exception then print if (genericExceptions.length > 0) { System.out.println("Exception class object details:"); for (Type type : genericExceptions) { System.out.println(type.getTypeName()); } } System.out.println(); } } } catch (Exception e) { e.printStackTrace(); } }}// a simple classclass demoClass { String value; // throw some exception by method public void setValue(String value) throws ClassNotFoundException, ArrayIndexOutOfBoundsException, ArithmeticException { this.value = value; } // method throwing no exception public String getValue() { return this.value; }} |
Output:
Generic Exception Thrown by Method: getValue Generic Exception Type Array length: 0 Generic Exception Thrown by Method: setValue Generic Exception Type Array length: 3 Exception class object details: java.lang.ClassNotFoundException java.lang.ArrayIndexOutOfBoundsException java.lang.ArithmeticException
Program 2: Check for a specific Exception
Java
/** Program Demonstrate how to* apply getGenericExceptionTypes() method*/import java.lang.reflect.Method;import java.lang.reflect.Type;public class GFG { // a simple class class GFGSampleClass { String value; // throw some exception by method public void setValue(String value) throws ClassNotFoundException, ArrayIndexOutOfBoundsException, ArithmeticException { this.value = value; } } // 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(); // get Method Object for setValue Method method = null; for (Method m : methods) { if (m.getName().equals("setValue")) method = m; } // check whether method throw // ArithmeticException Exception Type arithmeticExClassobj = ArithmeticException.class; boolean response = isCertainExceptionIsThrown(method, arithmeticExClassobj); System.out.println("ArithmeticException" + " is thrown by setValue(): " + response); // check whether method throw // IndexOutOfBoundsException Exception Type exceptionObj = IndexOutOfBoundsException.class; 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, Type exceptionName) { // get all exception list using getGenericExceptionTypes() Type exceptions[] = method.getGenericExceptionTypes(); for (int i = 0; i < exceptions.length; i++) { // check exception thrown or not if (exceptions[i] == exceptionName) { return true; } } return false; }} |
Output:
ArithmeticException is thrown by setValue(): true IndexOutOfBoundsException is thrown by setValue(): false
Reference: https://docs.oracle.com/javase/8/docs/api/java/lang/reflect/Method.html#getGenericExceptionTypes–
