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Lecture 7: Review Exceptions IO

Review

Interfaces:

  • Must implement ALL the methods
  • All fields are final (cannot be changed)

关于继承这里讲的内容比较简单我就不再赘述了，简单来说就是父类与子类的关系。

Exceptions

Exception: Event that occurs when something "unexpected" happens

  • NullPointerException
  • ArrayIndexOutOfBoundsException
  • ClassCastException
  • RuntimeException

How do exceptions "happen":

Java doesn't know what to do, so

- Create an Exception object
- Includes some useful information
- "throws" the Exception

我们自己也可以使用throws语句来抛出异常

IO

InputStream有很多资料可以参考，需要的时候直接上手搜索相关的资料就好。