Common exceptions

The concept of abnormality ： Exception refers to abnormal things that happen during operation , It will interrupt the running program .

In life , According to the different exception corresponding processing , Without interrupting our lives .

exception handling ：Java Programming language uses exception handling mechanism to provide error handling ability for programs

step ： The way to deal with the exception in the program in advance , The program runs , Exception found , Handle exceptions , Finished processing , The program continues to run

Java The exception handling of 5 Keywords to achieve ：try,catch,finally,throw,throws

After abnormality ：1, location （ Find out what's unusual ）2, modify

try In the statement block, there are code logic blocks that may have exceptions 【try , catch Capture exception 】

try......catch.......finally [ If the exception is finally, that finally It will also present ] Except in one case ,JVM stop it

finally Processing logic includes those ？

        1.I/O The closing operation of flow is generally placed in finally In the block

        2. The database connection operation is generally placed in finally In the block

throws: Declaration exception （main If there is no in the method, it will throw Java virtual machine ） There is try,catch Just use throws

throw： Throw an exception 【 You can only throw it once, not many times 】

throwable： For the parent class Up again object

exception： By application Java Throw and handle non critical errors

error： A serious error that cannot be recovered by the program itself 【 Unavoidable 】

checked： Abnormal during inspection

Custom exception ：Java Of API Provide rich exception classes in

1. Inherit exception

2. Custom construction method

3. Use when needed throw new Custom exception