##### For example

- Run PMD on a Sourceforge project

## Coupling Rules

These are rules which find instances of high or inappropriate coupling between objects and packages.

### CouplingBetweenObjects

Rule counts unique attributes, local variables and return types within an object. An amount higher than specified threshold can indicate a high degree of coupling.

This rule is defined by the following Java class: net.sourceforge.pmd.rules.CouplingBetweenObjects

Here's an example of code that would trigger this rule:

    import com.Blah;
    import org.Bar;
    import org.Bardo;
    public class Foo {
     private Blah var1;
     private Bar var2;
     //followed by many imports of unique objects
     void ObjectC doWork() {
      Bardo var55;
      ObjectA var44;
      ObjectZ var93;
      return something;
     }
    }

This rule has the following properties:

Name | Default value | Description
--- | --- | ---
threshold | 20 | The unique type reporting threshold

### ExcessiveImports

A high number of imports can indicate a high degree of coupling within an object. Rule counts the number of unique imports and reports a violation if the count is above the user defined threshold.

This rule is defined by the following Java class: net.sourceforge.pmd.rules.ExcessiveImports

Here's an example of code that would trigger this rule:

    import blah.blah.Baz;
    import blah.blah.Bif;
    // 18 others from the same package elided
    public class Foo {
     public void doWork() {}
    }

This rule has the following properties:

Name | Default value | Description
--- | --- | ---
minimum | 30 | The import count reporting threshold

### LooseCoupling

Avoid using implementation types (i.e., HashSet); use the interface (i.e, Set) instead

This rule is defined by the following Java class: net.sourceforge.pmd.rules.design.LooseCoupling

Here's an example of code that would trigger this rule:

    import java.util.*;
    public class Bar {
     // Use List instead
     private ArrayList list = new ArrayList();
     // Use Set instead
     public HashSet getFoo() {
      return new HashSet();
     }
    }