This is a generic Comparator for any kind of Comparable object, not just String:
package util;
import java.util.Comparator;
/**
* The Default Comparator for classes implementing Comparable.
*
* @param <E> the type of the comparable objects.
*
* @author Michael Belivanakis (michael.gr)
*/
public final class DefaultComparator<E extends Comparable<E>> implements Comparator<E>
{
@SuppressWarnings( "rawtypes" )
private static final DefaultComparator<?> INSTANCE = new DefaultComparator();
/**
* Get an instance of DefaultComparator for any type of Comparable.
*
* @param <T> the type of Comparable of interest.
*
* @return an instance of DefaultComparator for comparing instances of the requested type.
*/
public static <T extends Comparable<T>> Comparator<T> getInstance()
{
@SuppressWarnings("unchecked")
Comparator<T> result = (Comparator<T>)INSTANCE;
return result;
}
private DefaultComparator()
{
}
@Override
public int compare( E o1, E o2 )
{
if( o1 == o2 )
return 0;
if( o1 == null )
return 1;
if( o2 == null )
return -1;
return o1.compareTo( o2 );
}
}
How to use with String:
Comparator<String> stringComparator = DefaultComparator.getInstance();