try catch statement in java lang

Question

i have a statement like this that gives an error "missing return statement".But i assigned return statements as you see.whats wrong?

public int compareTo (Object o)
{
    try 
      {
          Sports m = (Sports)o;
          if(this.date.before(m.date)&& o instanceof x)
          {
             return -1;
          }
          else if(this.date.equals(m.date)&& o instanceof x)
          {
            return 0;
          }
          else
          { 
            return 1;
          }
    }

    catch(IllegalArgumentException e) 

    {
        System.out.print("Not an instance of x class");
    }
}

Try using proper braces or at least indentation, this code is also not much readable. — Sachin
– Sachin, Commented May 20, 2011 at 13:37
multiple returns is bad form and a single return after the catch block is sufficient — user177800
– user177800, Commented May 20, 2011 at 14:19

Jon Skeet · Accepted Answer · 2011-05-20 13:32:55Z

5

Yes - if IllegalArgumentException is caught, you're not returning anything.

To be honest, it's very rarely a good idea to catch IllegalArgumentException. Why are you catching it here?

answered May 20, 2011 at 13:32

Jon Skeet

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4 Comments

rena-c Over a year ago

i want to catch that exception if o is not an instance of class x.isnt it right to throw an illegal argument exception if x is not an instance of x class.

Robin Green Over a year ago

@cane-r OK, there's several confusions here. instanceof doesn't throw an exception, it just yields true or false. Casting does throw an exception - but ClassCastException, not IllegalArgumentException. Some methods may choose to throw IllegalArgumentException for a wrong argument type. Finally, what is x? A class placeholder?

rena-c Over a year ago

@robin i might be wrong.how i do this:if object o is not instance of the x class it throws an IllegalArgumentException.its like you enter a double integer in a program but you have to enter an int.so the program throws an exception that says enter an int.similar to this,you have to enter an object that an instance of class x.

Jon Skeet Over a year ago

@cane-r: If you want to throw an exception, you need to throw it - not catch it.

Ravi Parekh · Accepted Answer · 2011-05-20 13:41:25Z

2

if u want to use catch

int returnResult = -99;
try{

        returnResult = -1 ;
         else 
        returnResult = 0;
         else 
        returnResult = 1;
 }   catch(IllegalArgumentException e) {
    System.out.print("Not an instance of x class");
}
return returnResult;

answered May 20, 2011 at 13:41

Ravi Parekh

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Comments

Mike Thomsen · Accepted Answer · 2011-05-20 13:35:28Z

0

It's raising a compiler issue because there is a scenario with no return: when an exception is thrown. You need to add a return statement after the catch if you're really going to catch IllegalArgumentException.

answered May 20, 2011 at 13:35

Mike Thomsen

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1 Comment

Robin Green Over a year ago

After the catch block, or at the end of the catch block.

amukhachov · Accepted Answer · 2011-05-20 14:09:33Z

0

this.date.before(m.date)

it's the only piece of code which could generate IllegalArgumentException. Are you sure that you want to catch it? If you just want to be sure o is instance of x do smth like:

public int compareTo (Object o){
if(o instanceof x) {
    Sports m = (Sports)o;
    if(this.date.before(m.date)&& o instanceof x)
        return -1;
    else if(this.date.equals(m.date)&& o instanceof x)
        return 0;
    else 
        return 1;
}
else {
    System.out.print("Not an instance of x class");
    return 2; 
}

}

edited May 20, 2011 at 14:09

answered May 20, 2011 at 13:53

amukhachov

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