I've created a simple test class with one method:
public class TestClass {
int a = 0;
public void test() {
synchronized(TestClass.class) {
a = 1;
}
}
}
After opening the generated class file with Eclipse I got the next
result (I've removed the parts that are irrelevant)
public void test();
0 ldc <Class TestClass> [1]
2 dup
3 astore_1
4 monitorenter
5 aload_0 [this]
6 iconst_1
7 putfield TestClass.a : int [12]
10 aload_1
11 monitorexit
12 goto 18
15 aload_1
16 monitorexit
17 athrow
18 return
Exception Table:
[pc: 5, pc: 12] -> 15 when : any
[pc: 15, pc: 17] -> 15 when : any
I do understand that after the monitor is entered it is very important
that it leaves it again with the instruction monitorexit. In normal
case where no exceptions occur it will call monitorexit at the address
11. But if an exception occurs it has to make sure monitorexit is
called and therefore the exception table defines in the first entry
that on any exception the VM jumps to address 15. Until here
everything is understandable, but what is the second entry in the
exception table telling me? if an exception occurs betweern 15 and 17
then jump to 15 ... doesn't this cause an endless loop?
