Csharp/CSharp Tutorial/Language Basics/Custom Exception
Содержание
- 1 A custom exception with HelpLink and Source
- 2 Create your own exception class based on Exception
- 3 CustomException is an application exception that supports remoting.
- 4 Derived exceptions must appear before base class exceptions.
- 5 Extends Exception
- 6 Use a custom Exception
- 7 User-Defined Exception Classes
A custom exception with HelpLink and Source
<source lang="csharp">using System; public class CustomException : ApplicationException {
public CustomException(string Message) : base(Message)
{
this.HelpLink = "See the Readme.txt file";
this.Source = "My Program";
}
} class MainClass {
public static void Main()
{
try
{
Console.WriteLine("Throwing a new CustomException object");
throw new CustomException("My CustomException message");
}
catch (CustomException e)
{
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>
Throwing a new CustomException object HelpLink = See the Readme.txt file Message = My CustomException message Source = My Program StackTrace = at MainClass.Main() TargetSite = Void Main()
Create your own exception class based on Exception
<source lang="csharp">using System; using System.Collections; public class MyException : Exception {
public MyException( String reason, Exception inner ) :base( reason, inner ) {
}
} public class MainClass {
static void Main() {
try {
try {
ArrayList list = new ArrayList();
list.Add( 1 );
Console.WriteLine( "Item 10 = {0}", list[10] );
}
catch( ArgumentOutOfRangeException x ) {
throw new MyException( "I"d rather throw this",x ) ;
}
finally {
Console.WriteLine( "Cleaning up..." );
}
}
catch( Exception x ) {
Console.WriteLine( x );
Console.WriteLine( "Done" );
}
}
}</source>
Cleaning up... MyException: I"d rather throw this ---> System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index at System.Collections.ArrayList.get_Item(Int32 index) at MainClass.Main() --- End of inner exception stack trace --- at MainClass.Main() Done
CustomException is an application exception that supports remoting.
<source lang="csharp">using System; using System.Reflection; using System.Runtime.Serialization; [assembly: AssemblyVersion("1.1.0.0")] [assembly: AssemblyCultureAttribute("")]
[Serializable] public class CustomException : Exception {
public CustomException(): base("custom exception", null) {
prop_Time = DateTime.Now.ToLongDateString() + " " + DateTime.Now.ToShortTimeString();
}
protected CustomException(SerializationInfo info,StreamingContext context)
: base(info, context) {
prop_Time = info.GetString("Time");
}
public override void GetObjectData(SerializationInfo info, StreamingContext context) {
info.AddValue("Time", prop_Time, typeof(string));
base.GetObjectData(info, context);
}
protected string prop_Time = null;
public string Time {
get {
return prop_Time;
}
}
}</source>
Derived exceptions must appear before base class exceptions.
<source lang="csharp">using System;
class MyException : ApplicationException {
public MyException() : base() { }
public MyException(string str) : base(str) { }
public override string ToString() {
return Message;
}
}
class MyDerivedException : MyException {
public MyDerivedException() : base() { }
public MyDerivedException(string str) : base(str) { }
public override string ToString() {
return Message;
}
}
class MainClass {
public static void Main() {
for(int x = 0; x < 3; x++) {
try {
if(x==0)
throw new MyException("Caught an MyException exception");
else if(x==1)
throw new MyDerivedException("Caught an MyDerivedException exception");
else
throw new Exception();
}
catch (MyDerivedException exc) {
// catch the exception
Console.WriteLine(exc);
}
catch (MyException exc) {
// catch the exception
Console.WriteLine(exc);
}
catch (Exception exc) {
Console.WriteLine(exc);
}
}
}
}</source>
Caught an MyException exception Caught an MyDerivedException exception System.Exception: Exception of type "System.Exception" was thrown. at MainClass.Main()
Extends Exception
<source lang="csharp">using System; using System.Runtime.Serialization; [Serializable] public sealed class MyException : Exception {
private string stringInfo;
private bool booleanInfo;
public MyException() : base() { }
public MyException(string message) : base(message) { }
public MyException(string message, Exception inner): base(message, inner) { }
private MyException(SerializationInfo info, StreamingContext context) : base(info, context)
{
stringInfo = info.GetString("StringInfo");
booleanInfo = info.GetBoolean("BooleanInfo");
}
public MyException(string message, string stringInfo, bool booleanInfo) : this(message)
{
this.stringInfo = stringInfo;
this.booleanInfo = booleanInfo;
}
public MyException(string message, Exception inner, string stringInfo, bool booleanInfo): this(message, inner)
{
this.stringInfo = stringInfo;
this.booleanInfo = booleanInfo;
}
public string StringInfo
{
get { return stringInfo; }
}
public bool BooleanInfo
{
get { return booleanInfo; }
}
public override void GetObjectData(SerializationInfo info, StreamingContext context)
{
info.AddValue("StringInfo", stringInfo);
info.AddValue("BooleanInfo", booleanInfo);
base.GetObjectData(info, context);
}
public override string Message
{
get
{
string message = base.Message;
if (stringInfo != null)
{
message += Environment.NewLine + stringInfo + " = " + booleanInfo;
}
return message;
}
}
} public class MainClass {
public static void Main()
{
try
{
throw new MyException("Some error", "SomeCustomMessage", true);
}
catch (MyException ex)
{
Console.WriteLine(ex.Message);
Console.WriteLine(ex.BooleanInfo);
Console.WriteLine(ex.StringInfo);
}
}
}</source>
Some error SomeCustomMessage = True True SomeCustomMessage
Use a custom Exception
<source lang="csharp">using System;
class RangeArrayException : ApplicationException {
public RangeArrayException() : base() { }
public RangeArrayException(string str) : base(str) { }
public override string ToString() {
return Message;
}
}
class MainClass {
public static void Main() {
try {
throw new RangeArrayException("Low index not less than high.");
} catch (RangeArrayException exc) {
Console.WriteLine(exc);
}
}
}</source>
Low index not less than high.
User-Defined Exception Classes
<source lang="csharp">using System; public class CountIsZeroException: ApplicationException{
public CountIsZeroException(){
}
public CountIsZeroException(string message) : base(message)
{
}
public CountIsZeroException(string message, Exception inner) : base(message, inner)
{
}
} class MainClass{
public static void Main() {
try {
DoAverage();
}
catch (CountIsZeroException e)
{
Console.WriteLine("CountIsZeroException: {0}", e);
}
}
public static void DoAverage() {
throw(new CountIsZeroException("Zero count in DoAverage"));
}
}</source>
CountIsZeroException: CountIsZeroException: Zero count in DoAverage at MainClass.DoAverage() at MainClass.Main()
