What is InvocationTargetException

InvocationTargetException is an exception class in the Java programming language, used to represent exceptions that occur during method invocation. When using the reflection mechanism to call a method or constructor, if the called method or constructor itself throws an exception, but the code segment that calls the invoke() method does not catch the exception, the invoke() method will encapsulate the exception. in an InvocationTargetException and throw it.

InvocationTargetException is an exception class in the Java programming language, used to represent exceptions that occur during method invocation. It is thrown by the Method class in the java.lang.reflect package and the invoke() method in the Constructor class and is used to call other methods or constructors.

When using the reflection mechanism to call a method or constructor, if the called method or constructor itself throws an exception, but the code segment that calls the invoke() method does not catch the exception, then invoke() The method will encapsulate this exception in an InvocationTargetException and throw it.

InvocationTargetException is a checked exception that inherits from the ReflectiveOperationException class in the java.lang.reflect package, which inherits from the java.lang.Exception class. This means that when writing code, we must handle or declare the exception explicitly.

InvocationTargetException contains a cause attribute, which indicates the cause of the exception thrown by calling the target method or constructor. By calling the getCause() method of InvocationTargetException, we can obtain the original exception and further analyze and process it.

Usually, when using reflection to call a method or constructor, if the target function throws a checked exception, we can handle this exception by catching InvocationTargetException. After catching the InvocationTargetException, we can get the actual exception by calling the getCause() method, and handle it accordingly according to the specific business logic.

The following is an example that shows how to use InvocationTargetException to handle exceptions:

try {
    // 获取目标方法
    Method method = MyClass.class.getMethod("myMethod");
    
    // 调用目标方法
    method.invoke(new MyClass());
} catch (InvocationTargetException e) {
    // 获取原始异常
    Throwable cause = e.getCause();
    
    // 根据实际业务逻辑处理异常
    if (cause instanceof MyException) {
        // 处理MyException异常
    } else {
        // 处理其他异常
    }
} catch (NoSuchMethodException | IllegalAccessException e) {
    // 处理其他异常
}

In the above example, if the target method myMethod throws a MyException exception, then when the invoke() method is called , InvocationTargetException will encapsulate this exception and throw it. We can get the original MyException exception by catching InvocationTargetException and calling the getCause() method, and handle it according to the actual business logic.

Summary

InvocationTargetException is an exception class used to represent an exception that occurs when a method or constructor is called reflectively. It encapsulates exceptions thrown by target methods or constructors and provides a mechanism to handle these exceptions.

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