Functional Programming in java Venkat Subramaniam memoizer -

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in book functional programming in java venkat subramaniam, autor gives example of memoizer works perfectly, next leave implementation of memoizer class:

public class memoizer {     public static <t,r> r callmemoizer( final bifunction< function<t,r>,t,r> function, final t input ){         function<t,r> memoized = new function<t,r>(){             hashmap<t,r> store = new hashmap<>();             @override             public r apply(t input) {                 return store.computeifabsent(input, key -> function.apply(this, key));             }         };         return memoized.apply(input);     } }

so here question, wouldn't function memoized created in every call method callmemoizer? assume not because other ways hashmap store won't storing values... please explain me how , why piece of code works...

the local variable function<t,r> memoized = new function<t,r>() created each time callmemoizer invoked. important point however, expensive calculation , association key happen once (assuming map not weak/soft) via computeifabsent


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