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javadesign-patternsif-statementcomparatorcomparable

Java: Implement Compararable but too many conditional ifs. How can I avoid them?

I have a list of objects which implement Comparable.

I want to sort this list and that is why I used the Comparable.

Each object has a field, weight that is composed of 3 other member int variables.

The compareTo returns 1 for the object with the most weight.
The most weight is not only if the 

weightObj1.member1 > weightObj2.member1  
weightObj1.member2 > weightObj2.member2  
weightObj1.member3 > weightObj2.member3

but actually is a little more complicated and I end up with code with too many conditional ifs.

If the weightObj1.member1 > weightObj2.member1 holds then I care if weightObj1.member2 > weightObj2.member2.

and vice versa.

else if weightObj1.member2 > weightObj2.member2 holds then I care if weightObj1.member3 > weightObj2.member3 and vice versa.

Finally if weightObj1.member3 > weightObj2.member3 holds AND if a specific condition is met then this weightObj1 wins and vice versa

I was wondering is there a design approach for something like this?

Solution

  • The API for Comparable states:

    It is strongly recommended (though not required) that natural orderings be consistent with equals.

    Since the values of interest are int values you should be able to come up with a single value that captures all comparisons and other transformations you need to compare two of your objects. Just update the single value when any of the member values change.