Java 8 sort multiple objects

Question

   public class B {
              private String name;
              private String  value;

             //Setters and Get
       }        
       public class C {
             private String name;
             private String  value;
        //Setters and Get Methods
       }
        public class D {
             private String name;
             private String  value;
             //Setters and Get
        }
        public class A {
              private B b;
              private C c;
              private D d;
            // Setters and Get
         }
        public class  Example{
          List<A> a = new Array List<A>();
            //Lets assume a  will contain objects of class B, C and D
           a .sort( Comparator.comparing(A::getB().getName).thenComparing(A::getC().getName));

         }

Sort field from one pojo , then sort field by next pojo. Need to understand how to sort in this situation. Can we use Comparator.comparing ()in this case?

Mureinik · Accepted Answer · 2019-03-20 10:35:42Z

2

You can't use method refences like that, but you could just use lambda expressions:

a.sort(Comparator.comparing((A x) -> x.getB().getName())
                 .thenComparing(x -> x.getC().getName()));

edited Mar 20, 2019 at 10:35

answered Mar 19, 2019 at 17:47

Mureinik

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3 Comments

user3233289 Over a year ago

1) x.getB().getName()-- x should be type casted to Class A rite? 2) Should class A implement comparator? I am getting java.lang.ClassCastException: java.lang.Class cannot be cast to java.lang.Comparable

Holger Over a year ago

You need Comparator.comparing((A x) -> x.getB().getName()) .thenComparing(x -> x.getC().getName()), due to the limited type inference. @user3233289 it’s impossible to get that ClassCastException with what you have posted in your question.

user3233289 Over a year ago

Thank you!. That helped

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