package java_8;

    import org.junit.Test;

    import java.util.ArrayList;

    import java.util.Arrays;

    import java.util.List;

    import java.util.function.Consumer;

    import java.util.function.Predicate;

    import java.util.function.Supplier;

    import java.util.function.Function;

    /**

     * Java8内置的四大核心函数式接口

     * <p>

     * Consumer<T>: 消费型接口

     * void accept(T t);

     *

     * Supplier<T>:供给型接口

     * T get();

     *

     * Function<T, R>: 函数型接口

     * R apply(T t);

     *

     * Predicate<T>: 断言型接口:

     * boolean test(T t);

     *

     *Java8中还提供了其他函数式接口

     */

    public class TestLambda4 {

        //predicate<T> 断言型接口:

        @Test

        public void test4(){

            List<String> list = Arrays.asList("Hello","Lambda","Go","java");

            list = filterStr(list, s->s.contains("o"));

            list.forEach(System.out::println);

        }

        //需求:将满足条件的字符串添加到集合中

        public List<String> filterStr(List<String> list, Predicate<String> predicate) {

            List<String> stringList = new ArrayList<>();

            for (String str : list) {

                if (predicate.test(str))

                    stringList.add(str);

            }

            return stringList;

        }

        //-----------------------------------------------------------

        //Function<T,R>函数型接口

        @Test

        public void test3() {

            String str = strHandler("huangyichun", s -> s.toUpperCase());

            System.out.println(str);

        }

        //需求用于处理字符串

        public String strHandler(String str, Function<String, String> fun) {

            return fun.apply(str);

        }

        //-------------------------------------------------

        //Supplier<T>供给型接口:

        @Test

        public void test2() {

            List<Integer> list = getNumList(10, () -> (int) (Math.random() * 100));

            list.forEach(System.out::println);

        }

        //需求：产生指定个整数，并放入集合中

        public List<Integer> getNumList(int num, Supplier<Integer> sup) {

            List<Integer> list = new ArrayList<>();

            for (int i = 0; i < num; i++) {

                list.add(sup.get());

            }

            return list;

        }

        //-----------------------------------------------------------

        //Consumer<T> 消费型接口

        @Test

        public void test1() {

            happy(10000, m -> System.out.println(m));

        }

        public void happy(double money, Consumer<Double> con) {

            con.accept(money);

        }

    }