方法类| Java 中的 getGenericExceptionTypes()方法
原文:https://www . geesforgeks . org/method-class-getgenericexceptiontypes-method-in-Java/
java.lang.reflect 方法类的getGenericExceptionTypes()方法返回一个类型对象数组，表示方法对象为处理异常而抛出的异常。使用抛出子句的方法处理的所有异常都使用该方法作为类型对象的数组返回。如果应用此方法的方法在其抛出子句中声明没有异常，则此方法返回长度为 0 的数组。
示例:
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,
}
语法:
public Type[] getGenericExceptionTypes()
返回值:它返回由 this Method 对象引发的异常类型的数组
异常:该方法抛出以下异常:
- 泛型签名格式错误–如果泛型方法签名与 JVM 规范中指定的格式不同。
- 类型不存在异常–如果由 throws 子句指定的异常类型引用了不存在的类型声明。
- malformedparameterzedtypexception–如果基础可执行文件的 throws 子句引用了一个参数化类型，而该参数化类型由于任何原因无法实例化。
下面的程序说明了方法类的 getGenericExceptionTypes()方法:
程序 1: 借助 getGenericExceptionTypes()打印方法抛出的所有异常类型
/*
* 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 class
class 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
程序 2: 检查特定异常
/*
* 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 airthmeticExClassobj = ArithmeticException.class;
boolean response = isCertainExceptionIsThrown(method,
airthmeticExClassobj);
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
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