Why syntax limitation with try/catch?

[XmisterIS]

With reference to if blocks, I notice that you can do this:

if (condition1) method1();
else if (condition2) method2();
else if (condition3) method3();
//etc ...

... or this:

if (condition1) { method1(); }
else if (condition2) { method2(); }
else if (condition3) { method3(); }
//etc ...

... and the compiler is happy either way.

But if you try to do this (for example):

try method();
catch (Exception1 e1) err_method1(e1);
catch (Exception2 e2) err_method2(e2);
catch (Exception3 e3) err_method3(e3);

the compiler complains and insists that you do this:

try { method(); }
catch (Exception1 e1) { err_method1(e1); }
catch (Exception2 e2) { err_method2(e2); }
catch (Exception3 e3) { err_method3(e3); }

Why does it do that with try/catch but not if?

[JosAH]

Imagine a nested try ... catch( ... ) statement:

try {
   try {
      ...
   }
   catch ( ... ) ...
}
catch ( ... ) ...

Now imagine you don't need the curly brackets (i.e. a Statement instead of a Block syntactically):

try 
   try 
      ...
   catch( ... ) ...
catch( ... ) ...

You can't distinguish to wich try block the latest catch clause belongs anymore ...

kind regards,

Jos

[XmisterIS]

I see, yes it's different to if, I hadn't thought of that! ... but you could distinguish which block if there was an endtry keyword!

[JosAH]

I see ... but you could distinguish which block if there was an endtry keyword!

Yep, but there isn't an endtry keyword; that's not the way they have defined the syntax of the language.

kind regards,

Jos

[XmisterIS]

I know ... but they should! How dare they ... :p

[JosAH]

hai.... whn thre is possibility of arsing an exception tht should be kept in try catch block syntax limitation is tht for every try thre must be one catch block, a try can hve n no of catch blocks.... even , whn u don't mention the catch block and if the exception is arised thn it generally first checks for catch block if it is not handled tht exception goes to JVM thn JVM handles tht expection tht wasthe reason we will get the abnormal termination....

Example....


try{



}

catch()
{
}
catch(){
}

Counter example:

try
   try 
      ...
   catch ( ... ) ...
   catch ( ... ) ...
catch( ... ) ...

The catch block in the middle is 'dangling' if Statements would've been allowed instead of Blocks in try - catch statements.

kind regards,

Jos