CODEWITHSUNDEEP
javajava-8predicatefunctional-interface
Ishant Gaurav
Ishant Gaurav

Reputation: 1203

Create custom Predicate with Set<String> and String as parameter

I have a String as "ishant" and a Set<String> as ["Ishant", "Gaurav", "sdnj"] . I need to write the Predicate for this. I have tried as below code, but it is not working 

Predicate<Set<String>,String> checkIfCurrencyPresent = (currencyList,currency) -> currencyList.contains(currency);

How can I create a Predicate which will take Set<String> and String as a parameter and can give the result?

Upvotes: 9

Views: 2249

Answers (3)

Naman
Naman

Reputation: 32046

If you were to stick with using Predicate, use something similar as :

Set<String> currencies = Set.of("Ishant", "Gaurav", "sdnj");
String input = "ishant";
Predicate<String> predicate = currencies::contains;
System.out.print(predicate.test(input)); // prints false

The primary difference between the BiPredicate and Predicate would be their test method implementation. A Predicate would use

public boolean test(String o) {
    return currencies.contains(o);
}

and a BiPredicate would instead use 

public boolean test(Set<String> set, String currency) {
    return set.contains(currency);
}

Upvotes: 8

Hadi
Hadi

Reputation: 17299

Aomine's answer is complete. using of BiFunction<T, U, R> is another way: 

BiFunction<Set<String>,String,Boolean> checkIfCurrencyPresent = Set::contains;

Upvotes: 2

Ousmane D.
Ousmane D.

Reputation: 56489

A Predicate<T> which you're currently using represents a predicate (boolean-valued function) of one argument.

You're looking for a BiPredicate<T,U> which essentially represents a predicate (boolean-valued function) of two arguments.

BiPredicate<Set<String>,String>  checkIfCurrencyPresent = (set,currency) -> set.contains(currency);

or with method reference:

BiPredicate<Set<String>,String> checkIfCurrencyPresent = Set::contains;

Upvotes: 9

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