异常分类

  • 所有的错误类都是Throwable类的子孙类型
  • Throwable有两个直接子类，Error和Exception

以下，是Throwable的注释

The superclass of all classes which can be thrown by the VM. The
two direct subclasses are recoverable exceptions ({@code Exception}) and
unrecoverable errors ({@code Error}). This class provides common methods for
accessing a string message which provides extra information about the
circumstances in which the {@code Throwable} was created (basically an error
message in most cases), and for saving a stack trace (that is, a record of
the call stack at a particular point in time) which can be printed later.

A {@code Throwable} can also include a cause, which is a nested {@code
Throwable} that represents the original problem that led to this {@code
Throwable}. It is often used for wrapping various types of errors into a
common {@code Throwable} without losing the detailed original error
information. When printing the stack trace, the trace of the cause is
included.

翻译一下：

这是所有能被VM虚拟机抛出的类的总称。它有两个直接子类，一个是可以被的可恢复的Exception,另一个是不可恢复的Error
本类提供了用附加字符串描述产生时错误环境的基本方法（大多数情况下描述的是Error），同时本类> 也保存了错误栈，以便以后打印。

  • Error为Java运行时内部错误，或者资源耗尽，总之就是外部中断。不应该被程序catch。

{@code Error} is the superclass of all classes that represent unrecoverable
errors. When errors are thrown, they should not be caught by application
code.

  • 与之相反，Exception是由程序产生，也就可以被程序所抓住。

{@code Exception} is the superclass of all classes that represent recoverable
exceptions. When exceptions are thrown, they may be caught by application
code.

  • Exception 的子类也分两种，RuntimeException和 非 RuntimeException

  • RuntimeException指的是执行程序时出错，或者换句话说程序有错误。一种Unckecked Exception ( 没有被检查出来的错误 )。这种错误不应该（但可以）被捕捉，我们应该用更多的精力来把bug消除。而不是偷懒。

  • 诸如 IndexOutOfBoundsException 以及 NullPointerException都是这种错误，他本应该被检查出来，出了错只能怪你喽。

{@code RuntimeException} is the superclass of all classes that represent
exceptional conditions which occur as a result of executing an application in
the VM. Unlike checked exceptions (exceptions where the type
doesn’t extend {@code RuntimeException} or {@link Error}), the compiler does
not require code to handle runtime exceptions.

  • 非RuntimeException ，也就是Checked Exception如IOException
  • 这种错误不归你管，哪怕你检查的再仔细也不能避免。于是需要，throws以及catch
  • 遇到这种Checked Exception，编译器也会强制你抛出和捕捉错误。

##最后
一种常用错误，用IllegalAugmentException 来控制输入，如果不对报错就行了，强迫上层的人去判断