Csharp/C Sharp/Language Basics/Exception Throw
Содержание
- 1 Demonstrates rethrowing an exception from a method
- 2 Exception throw and catch
- 3 Exception throw and catch 2
- 4 Exception throws
- 5 illustrates creating and throwing an exception object
- 6 Intentionally throws an error to demonstrate Just-In-Time debugging
- 7 Let the C# runtime system handle the error
- 8 Manually throw an exception
- 9 Rethrow an exception
- 10 Throwing Your Own Exceptions
Demonstrates rethrowing an exception from a method
<source lang="csharp"> /* C# Programming Tips & Techniques by Charles Wright, Kris Jamsa Publisher: Osborne/McGraw-Hill (December 28, 2001) ISBN: 0072193794
- /
// Rethrow.cs -- Demonstrates rethrowing an exception from a method. // // Compile this program with the following command line: // C:>csc Rethrow.cs // namespace nsRethrow {
using System;
using System.IO;
public class Rethrow
{
static public void Main ()
{
while (true)
{
Console.Write ("Please enter a file name (return to exit): ");
string FileName = Console.ReadLine ();
if (FileName.Length == 0)
break;
try
{
ReadFile (FileName);
break;
}
catch (IOException e)
{
if (e is FileNotFoundException)
Console.WriteLine ("The file " + FileName + " was not found");
}
catch (Exception e)
{
Console.WriteLine (e.Message + "\n");
break;
}
}
}
static public void ReadFile (string FileName)
{
FileStream strm;
StreamReader reader;
try
{
strm = new FileStream (FileName, FileMode.Open);
reader = new StreamReader (strm);
string str = reader.ReadToEnd ();
Console.WriteLine (str);
}
catch (IOException e)
{
// If file not found, go back and get another name
if (e is FileNotFoundException)
throw (e);
// Code here to handle other IOException classes
Console.WriteLine (e.Message);
throw (new IOException());
}
}
}
}
</source>
Exception throw and catch
<source lang="csharp"> /* Learning C# by Jesse Liberty Publisher: O"Reilly ISBN: 0596003765
- /
using System;
namespace ExceptionHandling
{
public class TesterExceptionHandling2
{
static void Main()
{
Console.WriteLine("Enter Main...");
TesterExceptionHandling2 t = new TesterExceptionHandling2();
t.Run();
Console.WriteLine("Exit Main...");
}
public void Run()
{
Console.WriteLine("Enter Run...");
Func1();
Console.WriteLine("Exit Run...");
}
public void Func1()
{
Console.WriteLine("Enter Func1...");
Func2();
Console.WriteLine("Exit Func1...");
}
public void Func2()
{
Console.WriteLine("Enter Func2...");
try
{
Console.WriteLine("Entering try block...");
throw new System.Exception();
Console.WriteLine("Exiting try block...");
}
catch
{
Console.WriteLine("Exception caught and handled!");
}
Console.WriteLine("Exit Func2...");
}
}
}
</source>
Exception throw and catch 2
<source lang="csharp"> /* Learning C# by Jesse Liberty Publisher: O"Reilly ISBN: 0596003765
- /
using System;
namespace ExceptionHandling
{
public class TesterExceptionHandling3
{
static void Main()
{
Console.WriteLine("Enter Main...");
TesterExceptionHandling3 t = new TesterExceptionHandling3();
t.Run();
Console.WriteLine("Exit Main...");
}
public void Run()
{
Console.WriteLine("Enter Run...");
Func1();
Console.WriteLine("Exit Run...");
}
public void Func1()
{
Console.WriteLine("Enter Func1...");
try
{
Console.WriteLine("Entering try block...");
Func2();
Console.WriteLine("Exiting try block...");
}
catch
{
Console.WriteLine("Exception caught and handled!");
}
Console.WriteLine("Exit Func1...");
}
public void Func2()
{
Console.WriteLine("Enter Func2...");
throw new System.Exception();
Console.WriteLine("Exit Func2...");
}
}
}
</source>
Exception throws
<source lang="csharp"> /* Learning C# by Jesse Liberty Publisher: O"Reilly ISBN: 0596003765
- /
using System;
namespace ExceptionHandling
{
public class TesterExceptionHandling1
{
static void Main()
{
Console.WriteLine("Enter Main...");
TesterExceptionHandling1 t = new TesterExceptionHandling1();
t.Run();
Console.WriteLine("Exit Main...");
}
public void Run()
{
Console.WriteLine("Enter Run...");
Func1();
Console.WriteLine("Exit Run...");
}
public void Func1()
{
Console.WriteLine("Enter Func1...");
Func2();
Console.WriteLine("Exit Func1...");
}
public void Func2()
{
Console.WriteLine("Enter Func2...");
throw new System.Exception();
Console.WriteLine("Exit Func2...");
}
}
}
</source>
illustrates creating and throwing an exception object
<source lang="csharp"> /* Mastering Visual C# .NET by Jason Price, Mike Gunderloy Publisher: Sybex; ISBN: 0782129110
- /
/*
Example13_8.cs illustrates creating and throwing an exception object
- /
using System; public class Example13_8 {
public static void Main()
{
try
{
// create a new Exception object, passing a string
// for the Message property to the constructor
Exception myException = new Exception("myException");
// set the HelpLink and Source properties
myException.HelpLink = "See the Readme.txt file";
myException.Source = "My Example13_8 Program";
// throw the Exception object
throw myException;
}
catch (Exception e)
{
// display the exception object"s properties
Console.WriteLine("HelpLink = " + e.HelpLink);
Console.WriteLine("Message = " + e.Message);
Console.WriteLine("Source = " + e.Source);
Console.WriteLine("StackTrace = " + e.StackTrace);
Console.WriteLine("TargetSite = " + e.TargetSite);
}
}
}
</source>
Intentionally throws an error to demonstrate Just-In-Time debugging
<source lang="csharp"> /* C# Programming Tips & Techniques by Charles Wright, Kris Jamsa Publisher: Osborne/McGraw-Hill (December 28, 2001) ISBN: 0072193794
- /
// Throw.cs -- Intentionally throws an error to demonstrate // Just-In-Time debugging. // // Compile this program with the following command line: // C:>csc /debug:full Throw.cs // namespace nsThrow {
using System;
public class Throw
{
static public void Main ()
{
Console.WriteLine ("This program intentionally causes an error.");
int x = 42;
int y = 0;
int z = x / y;
}
}
}
</source>
Let the C# runtime system handle the error
<source lang="csharp"> /* C#: The Complete Reference by Herbert Schildt Publisher: Osborne/McGraw-Hill (March 8, 2002) ISBN: 0072134852
- /
// Let the C# runtime system handle the error.
using System;
public class NotHandled {
public static void Main() {
int[] nums = new int[4];
Console.WriteLine("Before exception is generated.");
// Generate an index out-of-bounds exception.
for(int i=0; i < 10; i++) {
nums[i] = i;
Console.WriteLine("nums[{0}]: {1}", i, nums[i]);
}
}
}
</source>
Manually throw an exception
<source lang="csharp"> /* C#: The Complete Reference by Herbert Schildt Publisher: Osborne/McGraw-Hill (March 8, 2002) ISBN: 0072134852
- /
// Manually throw an exception.
using System;
public class ThrowDemo {
public static void Main() {
try {
Console.WriteLine("Before throw.");
throw new DivideByZeroException();
}
catch (DivideByZeroException) {
// catch the exception
Console.WriteLine("Exception caught.");
}
Console.WriteLine("After try/catch block.");
}
}
</source>
Rethrow an exception
<source lang="csharp"> /* C#: The Complete Reference by Herbert Schildt Publisher: Osborne/McGraw-Hill (March 8, 2002) ISBN: 0072134852
- /
// Rethrow an exception.
using System;
class Rethrow {
public static void genException() {
// here, numer is longer than denom
int[] numer = { 4, 8, 16, 32, 64, 128, 256, 512 };
int[] denom = { 2, 0, 4, 4, 0, 8 };
for(int i=0; i<numer.Length; i++) {
try {
Console.WriteLine(numer[i] + " / " +
denom[i] + " is " +
numer[i]/denom[i]);
}
catch (DivideByZeroException) {
// catch the exception
Console.WriteLine("Can"t divide by Zero!");
}
catch (IndexOutOfRangeException) {
// catch the exception
Console.WriteLine("No matching element found.");
throw; // rethrow the exception
}
}
}
}
public class RethrowDemo {
public static void Main() {
try {
Rethrow.genException();
}
catch(IndexOutOfRangeException) {
// recatch exception
Console.WriteLine("Fatal error -- " +
"program terminated.");
}
}
}
</source>
Throwing Your Own Exceptions
<source lang="csharp">
using System;
class MyException : ApplicationException {
public MyException() : base("This is my exception message.")
{
}
}
class MainClass {
public static void Main()
{
try
{
MainClass MyObject = new MainClass();
MyObject.ThrowException();
}
catch(MyException CaughtException)
{
Console.WriteLine(CaughtException.Message);
}
}
public void ThrowException()
{
throw new MyException();
}
}
</source>
