The following function keeps returning the error message "This method must return a result of type int" and I cannot figure out why.
int
loaderResource( Plate agent ) {
if(agent.plateScale==SCALE25nm )
{if(loaders.get(0).isIdle)
return 0;
else
if(loaders.get(1).isIdle)
return 1;
else
if(loaders.get(2).isIdle)
return 2;
else
if(loaders.get(4).isIdle)
return 4;
else
if(loaders.get(5).isIdle)
return 5;
;}
else
if(agent.plateScale==SCALE200pm)
{if(loaders.get(3).isIdle)
return 3;
else
if(loaders.get(5).isIdle)
return 5;
;}
else
if(agent.plateScale==SCALE500pm)
{if(loaders.get(3).isIdle)
return 3;
else
if(loaders.get(5).isIdle)
return 5;}
else
if(agent.plateScale==SCALE100nm)
{if(loaders.get(4).isIdle)
return 4;}
;
}
Say agent.plateScale==314159
Do you see how there is no return statement? Add return -1 to the end, and check when you call the function that it is at least 0. If not throw a new Runtime Exception "Invalid input".
I agree with the previous answer. If all of the if conditions fail to evaluate to true then nothing will be returned which is why it is suggested you need a return statement at the end.
Also just a quick comment on the duplication in your code. You could extract out methods to check if a loader is idle or not. Say loaders is a list, pass the list down to the new method and iterate over its contents returning the index if it is indeed idle.
Also excessive use of if-else constructs can make code confusing and hard to read. You could store all the entries in a map and iterate over the keys and values. You could also use a switch but these can be controversial in there own right... the key is to try and minimize duplication and try keep the open closed principle (OCP) in mind when writing code.
Hope this helps.
Joe
If none of your 'if' statements is true, what integer value gets returned?
Your code does not say. This is why Java is giving you the error message.
As suggested above, add a final statement such as, return -1; or throw an exception to indicate to the caller that none of the conditions were true.
Hope this helps,
Dan
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Plating