Package io.vavr

Class Predicates

  • public final class Predicates
extends java.lang.Object
    Defines general-purpose predicates which are particularly useful when working with API.Match.

    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      private Predicates()  

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static <T> java.util.function.Predicate<T> allOf​(@NonNull java.util.function.Predicate<T> @NonNull ... predicates)
      Returns a predicate that is satisfied only when all of the provided predicates return true for a given input.
      static <T> java.util.function.Predicate<T> anyOf​(@NonNull java.util.function.Predicate<T> @NonNull ... predicates)
      Returns a predicate that is satisfied if at least one of the provided predicates returns true for a given input.
      static <T> java.util.function.Predicate<java.lang.Iterable<T>> exists​(@NonNull java.util.function.Predicate<? super T> predicate)
      Returns a predicate that checks if at least one element in an Iterable satisfies the given predicate.
      static <T> java.util.function.Predicate<java.lang.Iterable<T>> forAll​(@NonNull java.util.function.Predicate<? super T> predicate)
      Returns a predicate that checks if all elements in an Iterable satisfy the given predicate.
      static <T> java.util.function.Predicate<T> instanceOf​(@NonNull java.lang.Class<? extends T> type)
      Returns a Predicate that tests whether an object is an instance of the specified type.
      static <T> java.util.function.Predicate<T> is​(T value)
      Returns a Predicate that tests whether an object is equal to the specified value, using Objects.equals(Object, Object) for comparison.
      static <T> java.util.function.Predicate<T> isIn​(T @NonNull ... values)
      Returns a Predicate that tests whether an object is equal to at least one of the specified values, using Objects.equals(Object, Object) for comparison.
      static <T> java.util.function.Predicate<T> isNotNull()
      Returns a Predicate that tests whether an object is not null.
      static <T> java.util.function.Predicate<T> isNull()
      Returns a Predicate that tests whether an object is null.
      static <T> java.util.function.Predicate<T> noneOf​(@NonNull java.util.function.Predicate<T> @NonNull ... predicates)
      Returns a predicate that is satisfied if none of the provided predicates return true for a given input.
      static <T> java.util.function.Predicate<T> not​(@NonNull java.util.function.Predicate<? super T> predicate)
      Returns a predicate that negates the result of the given predicate.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • Predicates

        private Predicates()

    • Method Detail

      • allOf

        @SafeVarargs
public static <T> java.util.function.Predicate<T> allOf​(@NonNull java.util.function.Predicate<T> @NonNull ... predicates)
        Returns a predicate that is satisfied only when all of the provided predicates return true for a given input.

        If no predicates are supplied, the resulting predicate always evaluates to true.

        
 Predicate<Integer> isGreaterThanOne = i -> i > 1;
 Predicate<Integer> isGreaterThanTwo = i -> i > 2;

 allOf().test(0);                                   // true
 allOf(isGreaterThanOne, isGreaterThanTwo).test(3); // true
 allOf(isGreaterThanOne, isGreaterThanTwo).test(2); // false
        Type Parameters:
        T - the input type
        Parameters:
        predicates - the predicates to combine
        Returns:
        a predicate representing the logical conjunction of all given predicates
        Throws:
        java.lang.NullPointerException - if predicates is null

      • anyOf

        @SafeVarargs
public static <T> java.util.function.Predicate<T> anyOf​(@NonNull java.util.function.Predicate<T> @NonNull ... predicates)
        Returns a predicate that is satisfied if at least one of the provided predicates returns true for a given input.

        If no predicates are supplied, the resulting predicate always evaluates to false.

        
 Predicate<Integer> isGreaterThanOne = i -> i > 1;
 Predicate<Integer> isGreaterThanTwo = i -> i > 2;

 anyOf().test(0);                                   // false
 anyOf(isGreaterThanOne, isGreaterThanTwo).test(3); // true
 anyOf(isGreaterThanOne, isGreaterThanTwo).test(2); // true
 anyOf(isGreaterThanOne, isGreaterThanTwo).test(1); // false
        Type Parameters:
        T - the input type
        Parameters:
        predicates - the predicates to combine
        Returns:
        a predicate representing the logical disjunction of all given predicates
        Throws:
        java.lang.NullPointerException - if predicates is null

      • exists

        public static <T> java.util.function.Predicate<java.lang.Iterable<T>> exists​(@NonNull java.util.function.Predicate<? super T> predicate)
        Returns a predicate that checks if at least one element in an Iterable satisfies the given predicate.

        If the Iterable is empty, the resulting predicate evaluates to false.

        
 Predicate<Integer> isGreaterThanOne = i -> i > 1;
 Predicate<Iterable<Integer>> existsGreaterThanOne = exists(isGreaterThanOne);

 existsGreaterThanOne.test(List.of(0, 1, 2)); // true
 existsGreaterThanOne.test(List.of(0, 1));    // false
 existsGreaterThanOne.test(Collections.emptyList()); // false
        Type Parameters:
        T - the type of elements in the Iterable
        Parameters:
        predicate - the predicate to test elements against
        Returns:
        a predicate that evaluates to true if any element satisfies predicate
        Throws:
        java.lang.NullPointerException - if predicate is null

      • forAll

        public static <T> java.util.function.Predicate<java.lang.Iterable<T>> forAll​(@NonNull java.util.function.Predicate<? super T> predicate)
        Returns a predicate that checks if all elements in an Iterable satisfy the given predicate.

        If the Iterable is empty, the resulting predicate evaluates to true.

        
 Predicate<Integer> isGreaterThanOne = i -> i > 1;
 Predicate<Iterable<Integer>> forAllGreaterThanOne = forAll(isGreaterThanOne);

 forAllGreaterThanOne.test(List.of(0, 1, 2)); // false
 forAllGreaterThanOne.test(List.of(2, 3, 4)); // true
 forAllGreaterThanOne.test(Collections.emptyList()); // true
        Type Parameters:
        T - the type of elements in the Iterable
        Parameters:
        predicate - the predicate to test elements against
        Returns:
        a predicate that evaluates to true only if all elements satisfy predicate
        Throws:
        java.lang.NullPointerException - if predicate is null

      • instanceOf

        @GwtIncompatible
public static <T> java.util.function.Predicate<T> instanceOf​(@NonNull java.lang.Class<? extends T> type)
        Returns a Predicate that tests whether an object is an instance of the specified type. 
        
 Predicate<Object> instanceOfNumber = instanceOf(Number.class);

 instanceOfNumber.test(1);    // true
 instanceOfNumber.test("1");  // false
        Type Parameters:
        T - the type of objects being tested
        Parameters:
        type - the class to test instances against
        Returns:
        a predicate that evaluates to true if the object is an instance of type
        Throws:
        java.lang.NullPointerException - if type is null

      • is

        public static <T> java.util.function.Predicate<T> is​(T value)
        Returns a Predicate that tests whether an object is equal to the specified value, using Objects.equals(Object, Object) for comparison. 
        
 Predicate<Integer> isOne = is(1);

 isOne.test(1); // true
 isOne.test(2); // false
 isOne.test(null); // false
        Type Parameters:
        T - the type of object being tested
        Parameters:
        value - the value to compare against; may be null
        Returns:
        a predicate that evaluates to true if the tested object equals value

      • isIn

        @SafeVarargs
public static <T> java.util.function.Predicate<T> isIn​(T @NonNull ... values)
        Returns a Predicate that tests whether an object is equal to at least one of the specified values, using Objects.equals(Object, Object) for comparison. 
        
 Predicate<Integer> isIn = isIn(1, 2, 3);

 isIn.test(1); // true
 isIn.test(0); // false
 isIn.test(null); // false
        Type Parameters:
        T - the type of objects being tested
        Parameters:
        values - the values to compare against; may not be null
        Returns:
        a predicate that evaluates to true if the tested object equals any of the specified values
        Throws:
        java.lang.NullPointerException - if values is null

      • isNotNull

        public static <T> java.util.function.Predicate<T> isNotNull()
        Returns a Predicate that tests whether an object is not null. 
        
 Predicate<Integer> isNotNull = isNotNull();

 isNotNull.test(0);    // true
 isNotNull.test(null); // false
        Type Parameters:
        T - the type of object being tested
        Returns:
        a predicate that evaluates to true if the tested object is not null

      • isNull

        public static <T> java.util.function.Predicate<T> isNull()
        Returns a Predicate that tests whether an object is null. 
        
 Predicate<Integer> isNull = isNull();

 isNull.test(null); // true
 isNull.test(0);    // false
        Type Parameters:
        T - the type of object being tested
        Returns:
        a predicate that evaluates to true if the tested object is null

      • noneOf

        @SafeVarargs
public static <T> java.util.function.Predicate<T> noneOf​(@NonNull java.util.function.Predicate<T> @NonNull ... predicates)
        Returns a predicate that is satisfied if none of the provided predicates return true for a given input.

        If no predicates are supplied, the resulting predicate always evaluates to true.

        
 Predicate<Integer> isGreaterThanOne = i -> i > 1;
 Predicate<Integer> isGreaterThanTwo = i -> i > 2;

 noneOf().test(0);                                   // true
 noneOf(isGreaterThanOne, isGreaterThanTwo).test(1); // true
 noneOf(isGreaterThanOne, isGreaterThanTwo).test(2); // false
        Type Parameters:
        T - the input type
        Parameters:
        predicates - the predicates to combine
        Returns:
        a predicate that evaluates to true only if all predicates return false
        Throws:
        java.lang.NullPointerException - if predicates is null

      • not

        public static <T> java.util.function.Predicate<T> not​(@NonNull java.util.function.Predicate<? super T> predicate)
        Returns a predicate that negates the result of the given predicate. 
        
 // Negates a method reference
 Predicate<String> isNotNull1 = not(Objects::isNull);
 isNotNull1.test("");   // true
 isNotNull1.test(null); // false

 // Negates a predicate instance
 Predicate<String> isNotNull2 = not(Predicates.isNull());
 isNotNull2.test("");   // true
 isNotNull2.test(null); // false
        Type Parameters:
        T - the type of objects being tested
        Parameters:
        predicate - the predicate to negate
        Returns:
        a predicate that evaluates to true if the original predicate evaluates to false, and vice versa
        Throws:
        java.lang.NullPointerException - if predicate is null