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?
The predicate is a predefined functional interface in Java defined in the java. util. Function package. It helps with manageability of code, aids in unit-testing, and provides various handy functions.
Interface BiPredicate<T,U>Represents a predicate (boolean-valued function) of two arguments. This is the two-arity specialization of Predicate . This is a functional interface whose functional method is test(Object, Object) .
Java IntPredicate interface is a predicate of one int-valued argument. It can be considered an operator or function that returns a value either true or false based on certain evaluation on the argument int value. IntPredicate is a functional interface whose functional method is boolean test(int a) .
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;
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);
}
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