CODEWITHSUNDEEP
javaeclipsefindbugssuppress-warnings
tttppp
tttppp

Reputation: 8183

Suppress FindBugs warnings in Eclipse

I am using a string as a lock and so want to ensure the object is a new instance. FindBugs complains because it's generally more efficient to define the string directly (with double quotes). My code looks like:

/** A lock for the list of inputs. */
@edu.umd.cs.findbugs.annotations.SuppressWarnings("DM_STRING_CTOR")
//We want a new String object here as this is a lock.
private final Object inputListLock = new String("inputListLock");

Am I doing something wrong here? The Eclipse FindBugs plugin is still reporting this as a problem:

Pattern id: DM_STRING_CTOR, type: Dm, category: PERFORMANCE

Using the java.lang.String(String) constructor wastes memory because the object so constructed will be functionally indistinguishable from the String passed as a parameter.  Just use the argument String directly.

Upvotes: 3

Views: 5144

Answers (3)

Stephen C
Stephen C

Reputation: 718788

The normal idiom is to do this:

private final Object inputListLock = new Object();

which saves space (relative to new String("someLock")) and gets rid of the pesky PMD warning. But if you really want the lock to be a String, there are other ways to create a copy of a String that PMD is unlikely to object to; e.g. 

private final Object inputListLock = "some".concat("Lock");

(Note that "someLock".concat("") doesn't actually create a new String!)

Upvotes: 2

tttppp
tttppp

Reputation: 8183

Ok, so although both the other answers were interesting and useful (+1 for both), I didn't end up changing the code and I'm going to accept my own answer. To satisfy FindBugs I moved the annotation from the member variable to the surrounding class.

I've looked for some time but I haven't found any information suggesting that the SuppressWarnings may only be applied to classes and methods. Neither have I found any examples of it being applied to member variables. So though this solution works I don't know that it's the 'right' solution (maybe there's still something wrong with my FindBugs/Eclipse setup for example).

Upvotes: 1

Cameron Skinner
Cameron Skinner

Reputation: 54306

Why not just declare the lock object as a new Object? You don't need to make it a String, since you don't do anything that requires the String-ness of the lock, and presumable you don't use it for anything other than locking.

Without seeing the rest of your code I can hazard a guess that you're locking on access to a list of some kind. You could use the list itself as the lock object. If it's private then there is no chance that someone else will cause a deadlock.

Upvotes: 5

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