java exception has occurred

class.Java.lang.IllegalAccessErrorIllegal access error. This exception is thrown when an application attempts to access, modify, or invoke the domain (field) of a class or call its methods, but violate the visibility declaration of a domain or method.Java.lang.IncompatibleClassChangeErrorIncompatible class change error. This exception is thrown when an incompatible change is made to the class definition on

InvocationTargetException of Java exception Handling (reflection exception)InvocationTargetException exception by Method.invoke (obj, args ...) Method is thrown. This exception is received when an exception is thrown inside the

1. Try catch An exception is a running error. It can be generated by the system during Java runtime, or manually by code. Five keywords try catch throw throws finally Try {} Catch (exceptiontype1 E1 ){...} Catch (exceptiontype2 E2) {system. Out. println (E2 );} ... Finally {} All exception types are subclasses of the built-in class throwable. Two branches:

exception from the way the exception occurred gradually spread out, first passed to the caller of the method, the method is low, the user again to its caller.。。Until it is finally uploaded to the main method, assume that the main method still does not handle the exception. The JVM will abort the program. and print the

exception of the switch branch, program code readability becomes poor.1.2. Exception handling mechanismWhen an exception is thrown in the program, the program jumps out of the code that caused the exception in the program, the Java Virtual machine detects the catch block th

Exceptions include compile exceptions and run-time exceptions, while compile-time exceptions are mainly our syntax exceptions, and run-time exceptions are primarily exceptions that occur during code runtime.Exceptions are handled as objects in Java, the root class is the Java.lang.Throwable class, and many exception classes are defined in Java (such as OutOfMemor

the container and be processed at an unexpected level.② It is possible to create and use an adapter (adapter) class to categorize event actions.③ is advantageous in distributing work to various classes.Focus on learning this event-handling model 3. EventsThe three elements of event handling.(1) The event source event source is the creator of an event, such as a button, a window, a text field, and so on.(2) Event type Java All events are encapsulated

Exception: an Exception occurs during the running of the program.1. Exception handling mechanism for Java exceptionsEarly cases:The programming languages used in the early stage did not provide special exception handling functions. The programmers can only use conditional st

programs are static statement segments directly included in the class.Java. lang. IllegalAccessErrorIllegal access error. This exception is thrown when an application attempts to access, modify the Field of a class, or call its method, but violates the visibility Declaration of the domain or method.Java. lang. IncompatibleClassChangeErrorIncompatible class change error. This exception is thrown when the cl

The problem with Java code that occurs during runtime is an exception. in the In Java, the exception information is encapsulated into a class. When a problem occurs, an exception class object is created and information about the exceptio