???? (Exception Handling)

1
????(Exception Handling)

• ???
• ??????
• ??????/???????/
• ???????????

2
?????????(1/3)

• readFile
• openFile
• determineSize
• allocateMemory
• readFileIntoMemory
• closeFile
• ????, W. D. Mitchell??, JAVA ??????, ?????,
  2001, pp. 3-8 3-10.

3
?????????(2/3)

• errorCodeType readFile
• initialize errorCode 0
• openFile
• if( fileIsOpen )
• determineSize
• if( gotFileLength )
• allocateEnoughMemory
• if( memoryAllocated )
• readFileIntoMemory
• if( readFailed )
• errorCode -1 handleError
• else
• errorCode -2 handleError

4
?????????(3/3)

• else
• errorCode -3 handleError
• closeFile
• if( fileDidNotClose errorCode 0 )
• errorCode -4 handleError
• else
• errorCode -5 handleError
• return errorCode

5
Try-Catch ??????(1/2)

• readFile
• try
• openFile
• determineSize
• allocateMemory
• readFileIntoMemory
• closeFile

6
Try-Catch ??????(2/2)

• catch( fileDidNotOpen )
• handleError // or throwException
• catch( sizeNotDetermined )
• handleError // or throwException
• catch( memoryAllocationFailed )
• handleError // or throwException
• catch( couldNotReadFile )
• handleError // or throwException
• catch( couldNotCloseFile )
• handleError // or throwException

7
??????

• ????????????,???????
• ????????????,??????,????
• ??????????, ?????????

8
UsingTryCatch.Program (1/3)

• using System
• namespace UsingTryCatch
• class Program
• /
• ??try...catch???
• 5/14/2007
• /
• static void Main(string args)

9
UsingTryCatch.Program (2/3)

• try
• Console.Write("???? ")
• int number int.Parse(Console.ReadLine())
  
• int result 5 / number
• catch (Exception e)
• Console.WriteLine("????")
• Console.WriteLine("???? " "\n\n"
• e.Message "\n")
• Console.WriteLine("???????????? "
• "\n\n" e.StackTrace "\n")

10
UsingTryCatch.Program (3/3)

• Console.WriteLine("??????? "
• "\n\n" e.TargetSite "\n")
• Console.WriteLine(
• "??????????? "
• "\n\n" e.Source "\n")
• Console.WriteLine("??????? "
• "\n\n" e.ToString() "\n")

11
UsingTryCatch2.Program (1/3)

• using System
• namespace UsingTryCatch2
• / ??????
• 5/14/2007
• /
• class Program
• static void Main(string args)
• bool success false
• do
• try

12
UsingTryCatch2.Program (2/3)

• Console.Write("???? ")
• int number int.Parse(Console.ReadLine(
  ))
• int result 5 / number
• Console.WriteLine("????" result)
• success true
• catch (FormatException e)
• Console.WriteLine("?????")
• Console.WriteLine(e.Message)
• catch (DivideByZeroException e)
• Console.WriteLine("?????")
• Console.WriteLine(e.Message)

13
UsingTryCatch2.Program (3/3)

• catch (Exception e)
• Console.WriteLine("????")
• Console.WriteLine(e.Message)
• finally
• if (!success) Console.WriteLine("????")
  
• while (!success)
• Console.ReadLine()

14
UserDefinedException.Program (1/6)

• using System
• namespace UserDefinedException
• /
• ????????????
• 5/14/2007
• /
• class Program
• static void Main(string args)
• int nStudents 3
• GradeTable table new GradeTable(nStudents)
  

15
??

• ??????-2????,????????????
• ????catch??????,?????
• ????,???????????????catch??????????????????

16
??

• ??FileDemo??,??????????????,?????????
• ????catch???,???????????

17
UserDefinedException.Program (2/6)

• try
• table0 90
• //table1 102
• table1 100
• table2 55
• Console.WriteLine("table0 "
  table0)
• Console.WriteLine("table1 "
  table1)
• Console.WriteLine("table2 "
  table2)
• //Console.WriteLine("table3 "
  table3)
• catch (GradeOutOfRangeException e)
• Console.WriteLine(e.ToString())

18
UserDefinedException.Program (3/6)

• catch (IndexOutOfRangeException e)
• Console.WriteLine(e.Message)
• catch (Exception e)
• Console.WriteLine(e.Message)
• Console.ReadLine()

19
UserDefinedException.Program (4/6)

• class GradeTable
• private int nStudents
• private int grades
• public GradeTable(int nStudents)
• this.nStudents nStudents
• grades new intnStudents
• public int thisint index
• get
• return gradesindex

20
UserDefinedException.Program (5/6)

• set
• if (value lt 0 value gt 100)
• throw new GradeOutOfRangeException(value)
• gradesindex value

21
UserDefinedException.Program (6/6)

• public class GradeOutOfRangeException
  ApplicationException
• private string message
• public GradeOutOfRangeException(int grade)
• base()
• message "??" grade "??0?100??"
• public override string ToString()
• return message

22
??????

• Exception
• ApplicationException
• SystemException
• ArithmeticException
• DivideByZeroException
• NotFiniteNumberException
• OverflowException
• FormatException
• InvalidCastException
• IndexOutOfRangeException
• NullReferenceException
• StackOverflowException
• IOException

23
??

• ????Square,?????a???????a????????????a????,???thro
  w????????
• ???????????
• ??????,???????-1????,?catch??,???????

24
NestedTryAndCatch.Program(1/8)

• using System
• namespace NestedTryAndCatch
• /
• ????try...catch?????
• 5/16/2007
• /
• class Program
• static void Main(string args)
• int nStudents 1
• bool validNStudents false

25
NestedTryAndCatch.Program(2/8)

• do
• Console.Write("?????? ")
• try
• nStudents int.Parse(Console.ReadLine()
  )
• if (nStudents gt 0) validNStudents
  true
• catch (FormatException e)
• Console.WriteLine(e.Message)
• catch (Exception e)
• Console.WriteLine(e.Message)
• while (!validNStudents)

26
NestedTryAndCatch.Program(3/8)

• try
• GradeTable table new GradeTable(nStudent
  s)
• for(int i0 iltnStudents i)
• bool validGrades false
• do
• Console.Write(
• "???"(i1)" ????? ")
• try
• tablei
• int.Parse(Console.ReadLine())
• Console.WriteLine("table"i" "
  
• tablei)

27
NestedTryAndCatch.Program(4/8)

• validGrades true
• catch (GradeOutOfRangeException e)
• Console.WriteLine(e.ToString())
• catch (FormatException e)
• Console.WriteLine(e.Message)
• while (!validGrades )

28
NestedTryAndCatch.Program(5/8)

• catch (IndexOutOfRangeException e)
• Console.WriteLine(e.Message)
• catch (Exception e)
• Console.WriteLine(e.Message)

29
NestedTryAndCatch.Program(6/8)

• class GradeTable
• private int nStudents
• private int grades
• public GradeTable(int nStudents)
• this.nStudents nStudents
• grades new intnStudents
• public int thisint index
• get
• return gradesindex

30
NestedTryAndCatch.Program(7/8)

• set
• if (value lt 0 value gt 100)
• throw new GradeOutOfRangeException(value)
• gradesindex value

31
NestedTryAndCatch.Program(8/8)

• public class GradeOutOfRangeException
  ApplicationException
• private string message
• public GradeOutOfRangeException(int grade)
• base()
• message "??" grade "?????"
• public override string ToString()
• return message

32
??

• ?NestedTryAndCatch????????????,??catch??????????
• ????????,???????End Of File???,????????
• ????,????End Of File???