四大内置核心函数式接口

1.Cosumer<T>消费型接口

void accept（T t）；

/**
 * @Author: 郜宇博
 * @Date: 2021/8/31 21:34
 * 四大核心内置接口
 */
public class BuiltInInterface {

    /**
     * 消费型接口
     * @param money
     * @param consumer
     */
    public void happy(int money, Consumer<Integer> consumer){
        consumer.accept(money);
    }
    @Test
    public void test(){
        happy(100,(Integer money)->{
            System.out.println("消费了"+money+"元");
        });
    }
    
}

2.Supploer< T> 供给型接口

T get();

@Test
public void test(){
    //每次调用供给型接口生产随机数，存储在arrayList中
    ArrayList<Integer> arrayList = product(10, ()-> new Random().nextInt(100));
    //遍历
    Iterator<Integer> iterator = arrayList.iterator();
    while (iterator.hasNext()) {
        System.out.println(iterator.next());
    }

}
public ArrayList<Integer> product(int count, Supplier<Integer> supplier){
    ArrayList<Integer> list = new ArrayList<>();
    //生产count次
    for (int i = 0; i < count; i++) {
        Integer num = supplier.get();
        list.add(num);
    }
    return list;
}

3.Function< T> 函数型接口

R apply(T t);

//函数式接口测试
@Test
public void test3(){
    final String oldStr = "\t\t\t你好";
    String strHandler = strHandler(oldStr,(str)->str.trim());
    System.out.println(oldStr);
    System.out.println(strHandler);
}

public String strHandler(String str, Function<String,String> function){
    String strHandler = function.apply(str);
    return strHandler;
}

4.Predicate< T>断言式接口

boolean test(T t);

@Test
public void test4(){
    List<String> list = Arrays.asList("abcd","abd","eww","dsadasdas","12");
    //接口实现为字符串长度大于3
    List<String> newList = strFilter(list,(str)->str.length()>3);
    System.out.println(newList);
}

//断言式接口
public List<String> strFilter(List<String> list, Predicate<String > predicate){
    List<String> newStrings = new ArrayList<>();
    for(String str: list){
        //满足断言条件的加入到新的集合中
        if (predicate.test(str)){
            newStrings.add(str);
        }
    }
    return newStrings;
}