源码展示

package java.util.function;

import java.util.Objects;

/**
 * Represents a predicate (boolean-valued function) of one argument.
 */
@FunctionalInterface
public interface Predicate<T> {

    /**
     * Evaluates this predicate on the given argument.
     */
    boolean test(T t);

    /**
     * Returns a composed predicate that represents a short-circuiting logical
     * AND of this predicate and another.
     */
    default Predicate<T> and(Predicate<? super T> other) {
        Objects.requireNonNull(other);
        return (t) -> test(t) && other.test(t);
    }

    /**
     * Returns a predicate that represents the logical negation of this
     * predicate.
     */
    default Predicate<T> negate() {
        return (t) -> !test(t);
    }

    /**
     * Returns a composed predicate that represents a short-circuiting logical
     * OR of this predicate and another.
     */
    default Predicate<T> or(Predicate<? super T> other) {
        Objects.requireNonNull(other);
        return (t) -> test(t) || other.test(t);
    }

    /**
     * Returns a predicate that tests if two arguments are equal according
     * to Objects#equals().
     */
    static <T> Predicate<T> isEqual(Object targetRef) {
        return (null == targetRef)
                ? Objects::isNull
                : object -> targetRef.equals(object);
    }
}


示例

import java.util.Objects;
import java.util.function.Predicate;

public class Test {
    public static void main(String args[]) {
        Predicate<String > p = (str)->{return Objects.equals("费哥哥", str);};
        System.out.println(p.test("费哥哥")); //true
    }
}