方法类 | Java中的 getExceptionTypes() 方法

“方法类”的Java.lang.reflect.Method.getExceptionTypes()方法返回一个异常类型类对象数组，声明为由方法对象抛出以处理方法内部的异常。使用 throwed 子句的方法处理的所有异常都作为使用此方法的 Class 对象数组返回。如果应用此方法的方法在其 throws 子句中未声明异常，则此方法返回长度为 0 的数组。

句法：

public Class[] getExceptionTypes()

返回值：该方法返回一个由this Method对象使用 throw 子句声明的异常类的数组

下面的程序说明了 Method 类的 getExceptionTypes() 方法：

示例 1：打印所有异常

/*
* 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

示例 2：检查 Method 对象是否抛出了某个定义的异常。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 Java