Comparable Interface

Objects that have an ordering are compared using the compareTo() method.

2. Comparable <T> Interface



Answer:
"apple", "orange", "plum".
This is the order that compareTo() would place the strings.






Comparable<T> Interface





    

    

    

        

            

                

            

        

    






An interface consists of constants and method declarations. The Comparable<T> interface consists of just one method (and no constants):





    
        

            
                
int compareTo( T obj )                        

Compare the object running
                obj, which 
 is of type T. Return a 
 negative integer, zero, or a 
 positive integer, when he 
 object running the method is 
 less than, equal, or greater 
 than obj.

            		
        

    




T stands for the type of the objects. If the objects are Strings, then T is String. Strings implement the Comparable<String> interface.


If an object is of a class that implements Comparable, then that object is less than, equal, or greater than any object of that class. compareTo() returns an integer
    to show which of these three relations hold.




    
        

             
            Relation
             
            objectA.compareTo( objectB )
        

        

            objectA
            Less Than
            objectB
            Negative Integer
        

        

            objectA
            Equal
            objectB
            Zero
        

        

            objectA
            Greater Than
            objectB
            Positive Integer
        

    






Question 2:
Does compartTo() tell us enough?
If any two objects can be compared, and the result is less than, equal, or greater 
than is this enough to put a collection of objects in order?