-
抽象方法
boolean test(T t); 该方法对传入的参数进行验证，满足条件返回true，否则返回false。
使用Lambda表达式实现Predicate接口
Predicate<String> predicate = e -> "mattie".equals(e);
predicate.test("mattie"); //true
predicate.test("hello"); //false
-
Predicate接口与BiFunction接口的结合使用
public static void main(String[] args) { List<String> names = Arrays.asList("ted", "mattie", "hello", "world"); //找出names中包含字母e的元素 List<String> result = getNameContainingCharacter("e", names, (t, u) -> { return u.stream().filter(name -> name.contains(t)).collect(Collectors.toList()); }); } public static List<String> getNameContainingCharacter(String c, List<String> names, BiFunction<String, List<String>, List<String>> biFunc) { return biFunc.apply(c, names); } 用Predicate接口传递`调用行为
public static void main(String[] args) {
List<Integer> list = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
PredicateDemo instance = new PredicateDemo();
instance.conditionFilter(list, e -> {return e > 5;});
instance.conditionFilter(list, e -> e % 2 == 0);
instance.conditionFilter(list, e -> true);//打印所有元素
}
public void conditionFilter(List<Integer> list, Predicate<Integer> predicate) {
list.forEach(e -> {
if (predicate.test(e)) {
System.out.println(e);
}
});
}
-
and,or,negate方法
Predicate<Integer> p = e -> e > 5;
//取反
instance.conditionFilter(list, p.negate()); // 5 6 7 8 9 10
//and
instance.conditionFilter(list, p.and(e -> e < 9));//6 7 8
//or
instance.conditionFilter(list, p.or(e -> e < 4));//1 2 3 6 7 8 9 10
-
isEqual方法说明static <T> Predicate<T> isEqual(Object targetRef) { return (null == targetRef) ? Objects::isNull //接口的函数引用实现，满足test方法签名的要求：接受一个参数，返回boolean值 : object -> targetRef.equals(object); //接口的lambda表达式实现，object就是test(T t)方法的参数t }
