unreported exception

[shana07]

I have unreported exceptions as below:

unreported exception java.lang.Exception; must be caught or declared to be thrown
Euclid euc = new Euclid();
^
unreported exception java.lang.Exception; must be caught or declared to be thrown
euc.methodEuclid(arrayArgs);
^
2 errors

Below is my code...what's wrong with it..
In my Euclid class already throws exception ...please help me

try
            {   
                BufferedReader inputA = new BufferedReader (new FileReader("A.txt"));
                BufferedReader inputB = new BufferedReader (new FileReader("B.txt"));                   
 
                for(int ind=0; ind<2;ind++)
                {
                    lineA = inputA.readLine(); 
                    lineB = inputB.readLine();                       
 
                    String a = lineA;
                    String b = lineB;
                    String[] arrayArgs = new String[] { a, b}; 
 
                    Euclid euc = new Euclid();
                    euc.methodEuclid(arrayArgs);    
 
               }
 
             } catch (FileNotFoundException e) 
              {
                   e.printStackTrace(); 
              }
 
             catch (IOException e) 
           {
              System.out.println("There was a problem creating/writing to the temp file");
              e.printStackTrace();
           } 

[dmjpro]

did u specify the method ,where u write the main code .....
like this .....

return_type method_name (args) throws Exception

that's why this error thrown by Compiler.

because the Exception is the base class of all exception classes.

actually here checked and unchecked exception come.

i think u got my point.

[shana07]

did u specify the method ,where u write the main code .....
like this .....

return_type method_name (args) throws Exception

that's why this error thrown by Compiler.

because the Exception is the base class of all exception classes.

actually here checked and unchecked exception come.

i think u got my point.

Yes, I think I got it.
Could you pls tell me how to tackle this problem?
I've tried to remove throws exception at both methods,
but I think it can't be removed (throws exception)

 public void methodEuclid(String[] arrayArgs)
    {
        int opcode = GCD; 
 
        BigInteger b1=null, b2=null;
        String out="";
 
        b2 = receiveNumber(arrayArgs[1]);
        b1 = receiveNumber(arrayArgs[0]);

[dmjpro]

it ll be better if u post ur total code.

then i can solve ur problem.

plz send.

[JosAH]

Basically exceptions come in two flavours: checked and unchecked exceptions.
The unchecked exceptions are thrown when a program error occurs such as
null pointers, division by zero, illegal arguments, array index out of bounds etc.

The compiler can't check on these exceptions so it doesn't. The checked
exceptions are usually external events that cause the program to fail such as
IO errors, broken socket connections etc. When a piece of code can throw
a checked exception it has to say so in its method header otherwise the
method can't throw such an exception. It can catch such exceptions and deal
with it (e.g. repair the situation, inform the user about it etc.)

The compiler checks your code for it: i.e. when your method can (in)directly
throw an exception it has to report it in its method header:

public void foo() throws FooExecption { ... }

If you fail to do that the compiler will flag that as a compilation error. Some
beginners are tempted to just write a "throws Exception" and forget about
the rest. This is a very bad habit because any other code calling your method
can't tell *what* exactly was thrown and act accordingly.

Exceptions must be part of the design, never just put "throws Exception"
at every method header when the compiler complains about it.

kind regards,

Jos

[shana07]

it ll be better if u post ur total code.

then i can solve ur problem.

plz send.

yes please help me to check my code..Thank you very much
The first code is from MyProgram class - I put main method here

public static void main (String[] args) 
  {
         String lineA = "";
         String lineB = ""; 
         try
            {   
                BufferedReader inputA = new BufferedReader (new FileReader("A.txt"));
                BufferedReader inputB = new BufferedReader (new FileReader("B.txt"));                   
 
                for(int ind=0; ind<20;ind++)
                {
                    lineA = inputA.readLine(); 
                    lineB = inputB.readLine();                       
 
                    String a = lineA;
                    String b = lineB;
                    String[] arrayArgs = new String[] { a, b}; 
 
                    Euclid euc = new Euclid();   //exception error
                    euc.methodEuclid(arrayArgs);  //exception error
               }
 
             } catch (FileNotFoundException e) 
              {
                   e.printStackTrace(); 
              }
 
             catch (IOException e) 
           {
            System.out.println("There was a problem creating/writing to the temp file");
              e.printStackTrace();
           }     
    ................
 

This is the Euclid class.

public class Euclid 
{
     public Euclid()throws Exception
     {
 
     }
 
     public void methodEuclid(String[] arrayArgs) throws Exception 
    {
        int opcode = GCD; 
 
        BigInteger b1=null, b2=null;
        String out="";
 
        b2 = receiveNumber(arrayArgs[1]);
        b1 = receiveNumber(arrayArgs[0]);
 
         switch (opcode) 
         {           
            case GCD:       out = b1.gcd(b2).toString();
                            break;
            default:        throw new Exception("invalid operation");
        }
 
          System.out.println(out);     }       
 
      private static final BigInteger receiveNumber(String str) throws Exception 
    {
        BigInteger b = null;
        String thisLine = null;
 
        b = new BigInteger(str);  
        return b;
    }    
}

[shana07]

Basically exceptions come in two flavours: checked and unchecked exceptions.
The unchecked exceptions are thrown when a program error occurs such as
null pointers, division by zero, illegal arguments, array index out of bounds etc.

The compiler can't check on these exceptions so it doesn't. The checked
exceptions are usually external events that cause the program to fail such as
IO errors, broken socket connections etc. When a piece of code can throw
a checked exception it has to say so in its method header otherwise the
method can't throw such an exception. It can catch such exceptions and deal
with it (e.g. repair the situation, inform the user about it etc.)

The compiler checks your code for it: i.e. when your method can (in)directly
throw an exception it has to report it in its method header:

public void foo() throws FooExecption { ... }

If you fail to do that the compiler will flag that as a compilation error. Some
beginners are tempted to just write a "throws Exception" and forget about
the rest. This is a very bad habit because any other code calling your method
can't tell *what* exactly was thrown and act accordingly.

Exceptions must be part of the design, never just put "throws Exception"
at every method header when the compiler complains about it.

kind regards,

Jos

Jos, thank you. I assume checked and unchecked exceptions are refer to reported and unreported exceptions that I am having now. I still don't get, why some methods don't need throws Exception? How about main method?
Sorry, still not crystall clear about it...

[JosAH]

Jos, thank you. I assume checked and unchecked exceptions are refer to reported and unreported exceptions that I am having now. I still don't get, why some methods don't need throws Exception? How about main method?
Sorry, still not crystall clear about it...

Not really: there are two type of exceptions: checked and unchecked. For the
checked exceptions you either have to catch and handle them or *report* that
your method lets that exception pass to its caller(s). If you do neither the
compiler will tell you that you forgot to report the exception. Reporting is
simply adding a "throws SuchAndSoException" to the method declaration.

kind regards,

Jos