Why it does not cimpile without finally ?

[chi Lin]

Could someone explain why the code does not compile {error mesg : missing return tatement !!} until the finally clause with "return 0" is added ?
thanks
public class Test_9_3_02_2245 {
public static int testX(int i) {
try { exGenerator(i);
}
catch (ArithmeticException aex) {
System.out.println("Arith : "+aex);
return 1;
}
catch ( NullPointerException nex) {
System.out.println("Null : "+ nex);
return 2;
}
catch (RuntimeException rex) {
System.out.println("Runtime : "+ rex);
return 3;
}
//finally {System.out.println("Finally"); return 0; } }
static void exGenerator(int exType) {
switch(exType){
case 1 : throw new NullPointerException();
case 2 : throw new ArithmeticException();
case 3 : throw new RuntimeException();
default: throw new ArrayIndexOutOfBoundsException();
}
}
public static void main(String[] args) {
if(args.length!=1) { System.out.println(testX(5));}
if (args.length==1) {
int extype = Integer.parseInt(args[0]);
System.out.println(testX(extype));
}
}
}

[Ron Newman]

Your method is declared to return an int, so all possible exit points from the method have to return an int.
You do not need to have a finally clause, but if you don't have one, the last statement of the method needs to return an int.
I don't think it's good style to use a return statement in the finally clause, because it will silently override the return statements in your exception-handling code.
[ September 04, 2002: Message edited by: Ron Newman ]

[Dave Vick]

You need the finally block because the method testX is declared to return an int. Each of the catch blocks returns an int and so does the finally block, but the actual body of the method itself doesn't. So, if you compile it without the finally block the compiler will complain about the method signature.

[Ron Newman]

Run that with an argument of 1, 2, or 3, and you may be very surprised by the return value printed out!