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private final String _lock = new String("LOCK").intern();

public void doSomething() {
  synchronized(_lock) {
    // ...
  }
}

According to the Java API \[[API 06|AA. Java References#API 06]\], class {{java.lang.String}} documentation:

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// This bug was found in jetty-6.1.3 BoundedThreadPool
private final String _lock = "LOCK";

// ...
  synchronized(_lock) { 
    // ...
  }
// ...

A String literal is a constant and is interned. Consequently, it suffers from the same pitfalls as the preceding noncompliant code example.

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private final String _lock = new String("LOCK");

public void doSomething() {
  synchronized(_lock) {
    // ...
  }
}

A String instance differs from a String literal. The instance has a unique reference and its own intrinsic lock that is not shared by other string object instances or literals. A better approach is to synchronize on an internal private final lock object as shown in the following compliant solution.

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