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Utility classes, APIs and tools for Java

There is a newer version: 0.99-alpha1

package net.sf.javagimmicks.collections.mapping;

import java.io.Serializable;

import net.sf.javagimmicks.collections.mapping.ValueMappings.Mapping;
import net.sf.javagimmicks.lang.LangUtils;

/**
 * An abstract implementation of {@link Mapping} that provides a default
 * implementation for all derivable methods.
 */
public abstract class AbstractValueMapping implements Mapping, Serializable
{
   private static final long serialVersionUID = -293860609319776316L;

   protected AbstractValueMapping()
   {}

   @Override
   public Mapping invert()
   {
      return new AbstractValueMapping()
      {
         private static final long serialVersionUID = -2436668735196156472L;

         @Override
         public Mapping invert()
         {
            return AbstractValueMapping.this;
         }

         @Override
         public R getLeftKey()
         {
            return AbstractValueMapping.this.getRightKey();
         }

         @Override
         public L getRightKey()
         {
            return AbstractValueMapping.this.getLeftKey();
         }

         @Override
         public E getValue()
         {
            return AbstractValueMapping.this.getValue();
         }
      };
   }

   @Override
   public boolean equals(final Object obj)
   {
      if (this == obj)
      {
         return true;
      }

      if (!(obj instanceof Mapping))
      {
         return false;
      }

      final Mapping other = (Mapping) obj;

      return getLeftKey().equals(other.getLeftKey()) && getRightKey().equals(other.getRightKey())
            && LangUtils.equalsNullSafe(getValue(), other.getValue());
   }

   @Override
   public int hashCode()
   {
      return 5 * getLeftKey().hashCode() + 7 * getRightKey().hashCode() + 3872123;
   }

   @Override
   public String toString()
   {
      return new StringBuilder()
            .append("[")
            .append(getLeftKey())
            .append("/")
            .append(getRightKey())
            .append(": ")
            .append(getValue())
            .append("]")
            .toString();
   }
}