import java.lang.Comparable ;

/**

* Utility class to compare two objects in the sense

* of the java.lang.Comparable interface

*

*/

public class RJavaComparator {

/**

* compares a and b in the sense of the java.lang.Comparable if possible

*

* <p>instances of the Number interface are treated specially, in order to

* allow comparing Numbers of different classes, for example it is allowed

* to compare a Double with an Integer. if the Numbers have the same class,

* they are compared normally, otherwise they are first converted to Doubles

* and then compared</p>

*

* @param a an object

* @param b another object

*

* @return the result of <code>a.compareTo(b)</code> if this makes sense

* @throws NotComparableException if the two objects are not comparable

*/

public static int compare( Object a, Object b ) throws NotComparableException{

int res ;

if( a.equals( b ) ) return 0 ;

// treat Number s separately

if( a instanceof Number && b instanceof Number && !( a.getClass() == b.getClass() ) ){

Double _a = Double.valueOf( ((Number)a).doubleValue() );

Double _b = Double.valueOf( ((Number)b).doubleValue() );

return _a.compareTo( _b );

}

if( ! ( a instanceof Comparable ) ) throw new NotComparableException( a );

if( ! ( b instanceof Comparable ) ) throw new NotComparableException( b );

try{

res = ( (Comparable)a ).compareTo( b ) ;

} catch( ClassCastException e){

try{

res = - ((Comparable)b).compareTo( a ) ;

} catch( ClassCastException f){

throw new NotComparableException( a, b );

}

}

return res ;

}

}