In Java, runtime errors are divided into two categories based on their nature: errors and exceptions. (Recommended learning: java course )
All exceptions in Java are objects generated by subclasses of the Throwable class, and all exception classes are subclasses of the Throwable class or a subclass of a subclass.
The Throwable class is a direct subclass of the Object class, and the Error class and Exception class are two direct subclasses of the Throwable class.
Inheritance relationship of Error:
##Inheritance relationship of Exception:
1.error: class includes some serious system error classes that cannot be handled by the program, such as memory overflow, virtual machine error, stack overflow, etc. This type of error is generally related to the hardware and has nothing to do with the program itself. It is usually handled by the system and cannot be captured and processed by the program itself. Common errors include: NotClassDeFountError (class undefined error), OutofMemoryError (memory overflow error), StackOverFlowError (stack overflow error).
2.Exception: Exceptions are divided into runtime exceptions and checked exceptions.
1) The Java compiler will ask us to catch the checked exception, which must be caught, otherwise it will not be compiled. Java believes that checked exceptions can be handled, so checked exceptions must be handled explicitly. Common checked exceptions include IOException and SqlException.
2) Runtime exception: Programmers do not need to manually catch. When a runtime exception occurs in the program, the Java virtual machine handles it. Common runtime exceptions include: null pointer exception, arithmetic exception, array out-of-bounds exception, etc.
error is a system error or resource error, which is uncontrollable.
Exception is caused by a program error. Checked exceptions must be displayed and processed by the programmer's try and catch in the program, but runtime exceptions do not need to be. It will have jvm for processing.
And all exceptions are subclasses of Throwable or subclasses of subclasses.
The above is the detailed content of what is the error in java. For more information, please follow other related articles on the PHP Chinese website!
