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The editor displays a warning when there are multiple catch blocks for the same try statement. However, this is allowed and often used style. Of course, the exceptions need to be in the "correct" order such that they can be caught properly.
Could you please provide a test case that shows this behavior? The "correct" order should already be checked. It should not complain if the "correct" order is used.
From mail message: My example uses an external library: JADE, the API is at http://jade.cselt.it/doc/api/index.html. The code is here: =========================== try { ... } catch(StaleProxyException spe) { spe.printStackTrace(); } catch(ControllerException ce) { ce.printStackTrace(); } =========================== The second catch is yellow with a warning "Catch block is hidden by another one in the same try statement" When I change the order of catches, the second one(StaleProxyException then) gives an error message "Unreachable catch block". Please keep the discussion here. It is easier to follow the thread. Thanks.
I download the source and compiled it, but I didn't find this specific error. Two things to check: 1) Are you sure that the ControllerException is not already handled in the try block. Something like: try { ... try { .... } catch(ControllerException e) { .... } .... } catch(StaleProxyException e) { .... } catch(ControllerException e) { .... } 2) Try to remove the second catch. The problem could be that this catch block is never reach because the only exception that could be thrown in the try block is a StaleProxyException. Let me know if your code matches one of the cases.
Here is a small test case that might reproduce what you have: class E1 extends Exception { } class E2 extends E1 { } public class A { static void foo() throws E2 { } public static void main(String[] args) { try { foo(); } catch(E2 e) { } catch(E1 e) { } } } The compiler reports: Compiled 19 lines in 2500 ms (7.6 lines/s) 3 .class files generated ---------- 1. WARNING in D:\temp\A.java (at line 17) } catch(E1 e) { } ^^^^^^ Catch block is hidden by another one in the same try statement ---------- 1 problem (1 warning) The reason is that the second catch cannot be reached when the first catch is there. It is not strictly unreachable in the JLS meaning, because a compatible exception can be thrown inside the try block. You might try to see if we can improve such a diagnosis, but according to what I tried, something must be wrong with your try statement. Besides this warning, I found lot of suspicious warnings compiling the JADE code using the Eclipse compiler (assignment with no effects, lot of non-static access and other warnings).
After trying lots of things based on your remarks, the following seems to be the cause: I have a comment in my code (/**- ... /**/). When the first part is removed the warning disappears! There is no real reason I can think how the two things a re connected. Thus, the bug must be somewhere else, such as the interpretation of comments in this fashion. Here is the full code of my class. If you remove the line with /**- the warning goes away. Reinserting it brings the warning back. You will need a class UserAgentGenerator (subclass of jade.core.Agent). package simedia; import jade.core.Runtime; import jade.core.Profile; import jade.core.ProfileImpl; import jade.wrapper.*; public class Mediashelf { private MainContainer mc; public Mediashelf() { Agent myAgent = null; try { // Get a hold on JADE runtime Runtime rt = Runtime.instance(); rt.setCloseVM(true); // Launch a complete platform on the 8888 port // create a default Profile Profile pMain = new ProfileImpl(null, 8888, null); mc = rt.createMainContainer(pMain); /**- // starting the RMA GUI AgentController rma = mc.createNewAgent ("rma", "jade.tools.rma.rma", new Object[0]); rma.start(); /**/ // create UserAgentGenerator myAgent = (Agent)mc.createNewAgent ("UserAgentGenerator", UserAgentGenerator.class.getName(), new Object[] { }); myAgent.start(); } catch(StaleProxyException spe) { spe.printStackTrace(); } catch(ControllerException ce) { ce.printStackTrace(); } } /** * This method starts the Mediashelf */ public static void main(String[] args) { new Mediashelf(); } }
This is not a bug. In your code, the first start() invocation (in comment) // starting the RMA GUI AgentController rma = mc.createNewAgent ("rma", "jade.tools.rma.rma", new Object[0]); rma.start(); throws a ControllerException whereas the second start() invocation: // create UserAgentGenerator myAgent = (Agent)mc.createNewAgent ("UserAgentGenerator", UserAgentGenerator.class.getName(), new Object[] { }); myAgent.start(); throws only a StaleProxyException. So when the two start() invocations are called, the two catch clauses are reachable, but when the first one is commented, the second catch clause is hidden by the first catch clause. Hope this explanation help to understand the code. Close as INVALID.
