C # abnormal processing mechanism preliminary
Today, I learned the C #'s abnormal handling mechanism, and now you will summarize the following:
First, C # exception handling is used to keywords
TRY is used to check an exception that occurs and helps send any possible exceptions.
Catch handles errors in a larger way to control, and you can have multiple CATCH clauses.
Finally's code blocks will be executed regardless of whether abnormalities have caused an exception.
Throw is used to trigger an exception, which can trigger predefined exceptions and custom exceptions.
Second, C # abnormal processing format
Try
{
Program block;
}
Catch (Exception E)
{
Exception handling code block;
}
Finally
{
The code block to be executed regardless of whether abnormalities occur;
}
Third, abnormal treatment
A simple example of a divisor and zero:
Public Class Divisoriszero
{
Private static void main ()
{
INT DIVIDEND = 10;
INT Divisor1 = 0;
INT Divisor2 = 5;
Int DivideValue;
Try
{
DivideValue = Dividend / Divisor1; // (1)
// DivideValue = Dividend / Divisor2; // (2)
System.console.writeline ("DivideValue = {0}", DiVideValue); // (3) This line will not be executed.
}
Catch
{
System.Console.writeline ("The passive exception value is: {0}", e);
}
Finally
{
System.console.writeline ("I will display anyway, I will show it.");
}
}
}
Note: (1) The line will be performed to throw an exception. If there is no Catch statement, the program will terminate, and the Catch clause without parameters can be used to capture any type of exception.
If (1) is released, enable (2) line, which means that the program does not have an exception, from output, the Finally code block will still be executed.
Multiple CATCH statements can be provided to the TRY statement to capture specific exceptions, as in the above example: 0 As the division, the DivideByzeroException type exception is triggered, and the CATCH statement in the above example can be modified as follows:
Catch (DivideByzeroExcection E)
{
System.console.writeline ("Zero cannot be used as a division! The abnormality value is: / n {0}", e);
}
Catch (Exception E)
{
System.Console.writeline ("Not / '' zero as an exception that caused by divisor /"! The exception value is: / n {0} ", e);
}
Why do you have a Catch (Exception E) clause? The reason is very simple, the Catch (DivideByzeroExcection e) clause can only capture specific exceptions, and the program code in the TRY may also produce other exceptions, which can only be captured by catch (Exception E).
The following table gives some common exceptions:
Commonly used in the SYSTEM namespace
Abnormal class name brief description
MEMBERACCESSEXCEPTION access error: Type member cannot be accessed argumentException parameter error: The parameter of the method is invalid
The argumentnullexception parameter is empty: pass an unacceptable empty parameter to the method
Arithmeticexception mathematical calculation error: Due to the abnormality caused by mathematical calculations, the coverage is wide.
ArrayTypeMatchThexception array type does not match
DivideByzeroException is zero
The format of the Formatexception parameter is incorrect
IndexOutofRangeException index is out of range, less than 0 or the index of the last element is large
INVALIDCASTEXCEPTION illegally enforced conversion, triggered during explicit conversion failure
MulticastNotSupportedException is not supported by multicast: combined two non-empty appointments fail
NotSupportedException calls are not implemented in the class
NullReferenceException triggered when references an empty reference object
OutofMemoryException cannot be caused for the new statement to allocate memory, insufficient memory
Overflowexception overflow
StackoverflowException stack overflow
TypeInitializationException Error Initiation Type: Static constructor triggered
NOTFINITENUMBEREXCEPTION 无限 无限 无限: Number is not legal
Fourth, define your own anomaly
In addition to predefined abnormalities, we can also create our own exception, the process is relatively simple:
(1) Declare an exception, the format is as follows:
Class ExceptionName: Exception {}
(Ii) Executivity:
Throw (ExceptionName);
Look at an example:
Class Iamsecondgrade: system.exception {} // declaration exception
Class Secondgrade
{
Public Static Int Mul (int first, int SECOND)
{
IF (First> 100 || SECOND> 100)
Throw new iamsecondgrade (); // triggered anomalies
Return (First * Second);
}
Public static void main ()
{
INT MUL_VALUE;
Try
{
Mul_Value = MUL (99, 56); System.Console.writeline ("99 and 56 accumulation: {0}", mul_value);
Mul_Value = MUL (101, 4);
System.console.writeline ("Exceeding is abnormal, this line is not executed.");
}
Catch (iamsecondgrade) // captures custom unusual exceptions
{
System.console.writeline ("I have the second grade, more than 100 multiplication, I won't. Hey, I have a customized exception.");
}
Catch (System.exception E)
{
System.console.writeline ("Non-customized exception. Its value is: {0}", e);
}
}
}
