5. Abnormal loss

5. Exception loss Scenario One: Catch exception, throw new exception

This situation is described in the previous article, the following code in the F () function throws an exception will be lost, you can use Exception ex=new Exception (); Ex.initcause (e); reserved exceptions

Try {     f ();  } Catch (Exception e) {     thrownew  Exception ();    }

Case two: There is a return statement in finally

The exception thrown in F () is not caught

Try {    f ();} finally {//try not to catch exceptions    using catch words behind return　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　;} 

Case two: The exception thrown in finally will lose the previous exception

Try {      try{            f ();      } finally {            g ();      }} Catch (Exception e) {      e.printstacktrace ();}   

Summarize:

1. Only exceptions in G () can be captured and exceptions in F () are not captured

Best not to throw exceptions in 2.finally

Exception Limits

1. The parent Class A has method F ()-throws an exception E1 subclass B has method F ()--a. Can throw an exception E1 B. can throw an exception E2 (E1 subclass) c. Do not throw an exception

2. Throwing a subclass exception can catch the exception of the parent class, and vice versa.

Example:

classBaseexceptionextendsexception{}classChildexceptionextendsbaseexception{}Abstract classinning{ Public Abstract voidAtBat ()throwsbaseexception;}classStorminningextendsinning{ Public voidAtBat ()throwschildexception{Throw Newchildexception ();}}

inheritance implements exception handling of interfaces---important knowledge points

Interface type1{    void F ()throws  clonenotsupportedexception;} Interface type2{    void F ()throws  interruptedioexception;} class Implements type1,type2{----If you implement only one interface, you can not throw an exception, or throw an exception thrown in the    interface and its subtype public void  f () {} The f () here must throw the intersection of the exceptions in the Type1,type2 (or you can not throw exceptions)

fine-grained handling of anomalies

• Nesting with try blocks, graded catch exceptions

• classreadfirstline{ PublicReadfirstline () {Try{BufferedReader in=NULL; Try{ in=NewBufferedReader (NewFileReader (NewFile ("Test.iml"))); } Catch(FileNotFoundException e) {e.printstacktrace ();//do not need to close file} String firstline =In.readline ();        System.out.println (Firstline); } Catch(Exception e) {
  In.close ();//Close output stream e.printstacktrace (); }        finally {                }    }}

5. Abnormal loss