resources.report.rules.pmd.UseConcurrentHashMap.html Maven / Gradle / Ivy

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UseConcurrentHashMap

UseConcurrentHashMap

Since Java5 brought a new implementation of the Map designed for multi-threaded access, you can perform efficient map reads without blocking other threads.



//Type[../VariableDeclarator/VariableInitializer//AllocationExpression/ClassOrInterfaceType[@Image != 'ConcurrentHashMap']]
/ReferenceType/ClassOrInterfaceType[@Image = 'Map']


Example(s):



public class ConcurrentApp {
  public void getMyInstance() {
    Map map1 = new HashMap(); 	// fine for single-threaded access
    Map map2 = new ConcurrentHashMap();  // preferred for use with multiple threads

    // the following case will be ignored by this rule
    Map map3 = someModule.methodThatReturnMap(); // might be OK, if the returned map is already thread-safe
  }
}