Ban a spesific function/constructor

[VirtualTim]

Basically I'm looking at banning the specific Thread constructor Thread(Runnable task), to force people to name their threads (ie: use Thread(Runnable task, String name)).

Currently I'm attempting to achieve this with regex, but it's pretty tricky as the runnable can be declared inline.
I was hoping that IllegalInstantiationCheck would achieve this, but that appears to ban all constructors, where I just want to ban one specific one.

Any ideas?

[nrmancuso]

@VirtualTim it sounds like MatchXPath could be perfect for your use case; we can help you to formulate an XPath expression. Please share an example of

but it's pretty tricky as the runnable can be declared inline

to make sure we can cover all cases.

[VirtualTim]

What I meant by inline Runnable is something like this:

new Thread(new Runnable() {
  @Override
  public void run() {
    do_something();
  }
}, "thread name").start();

As opposed to:

new Thread(do_something, "thread name").start();

or

new Thread(() -> do_something(), "thread name").start();

So any suggestion on using MatchXpath to match any use of Thread(Runnable task)?

I'm currently using the regex \bThread\([^,]*\), but that generates false positives.

[romani]

Try to use forbiddenapis tool

Example:

checkstyle/pom.xml

Line 1658 in c8ee5ba

<signaturesFile>${basedir}/config/signatures.txt</signaturesFile>

checkstyle/config/signatures.txt

Line 1 in c8ee5ba

com.puppycrawl.tools.checkstyle.DefaultConfiguration#getAttributeNames() @ Usage of deprecated API is forbidden. Please use DefaultConfiguration.getPropertyNames() instead.

[nrmancuso]

@VirtualTim this should work for you:

➜  src cat Test.java 
public class Test {
    void inlineGood() {
        new Thread(new Runnable() {
            @Override
            public void run() {}
        }, "thread name").start();
    }

    void inlineBad() {
        new Thread(new Runnable() { // violation
            @Override
            public void run() {}
        }).start();
    }

    void goodThreads() {
        new Thread(m(), "thread name").start();
        new Thread(() -> m(), "thread name").start();
    }

    void badThreads() {
        new Thread(m()).start(); // violation
        new Thread(() -> m()).start(); // violation
    }

    Runnable m() {
        return System.out::println;
    }
}

➜  src cat config.xml
<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
    "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
    "https://checkstyle.org/dtds/configuration_1_3.dtd">
<module name="Checker">
  <property name="severity" value="error"/>
  <property name="fileExtensions" value="java, properties, xml"/>
  <module name="TreeWalker">
    <module name="MatchXpath">

      <property name="query" value="//LITERAL_NEW
                [./IDENT[@text='Thread'] and .[2 > count(./ELIST/*)]]"/>
      <message key="matchxpath.match"
              value="Thread should be named via 'Thread(task, name)' constructor."/>
    </module>
  </module>
</module>

➜  src java -jar checkstyle-10.7.0-all.jar -c config.xml Test.java
Starting audit...
[ERROR] /home/nick/IdeaProjects/tester/src/Test.java:10:9: Thread should be named via Thread(task, name) constructor. [MatchXpath]
[ERROR] /home/nick/IdeaProjects/tester/src/Test.java:22:9: Thread should be named via Thread(task, name) constructor. [MatchXpath]
[ERROR] /home/nick/IdeaProjects/tester/src/Test.java:23:9: Thread should be named via Thread(task, name) constructor. [MatchXpath]
Audit done.
Checkstyle ends with 3 errors.

[VirtualTim]

Awesome, thanks for that, I'll give it a shot.
Edit: Works great. Thanks @nrmancuso.