Scala函数初识

 scala中的map语法：

def map[B](f: Int => B)(implicit ct: scala.reflect.ClassTag[B]): Array[B]
override def map[B](f: Int => B): scala.collection.mutable.ArraySeq[B]

 应用：给的scala函数要符合函数声明标准

计算方式为乘10

scala> arr
res55: Array[Int] = Array(1, 2, 3, 4, 5)

scala> arr.map((a: Int) => a * 10)
res56: Array[Int] = Array(10, 20, 30, 40, 50)

java实现：

package lucas;

import java.util.ArrayList;

public class MyList {
    private ArrayList<Integer> arrayList;

    public MyList(ArrayList<Integer> arrayList) {
        this.arrayList = arrayList;
    }

    public ArrayList<Integer> getNewArrayList(IOperate op) {
        return op.operate(arrayList);

    }

    public static void main(String[] args) {
        ArrayList<Integer> result = new ArrayList<>();
        ArrayList<Integer> integers = new ArrayList<>();
        integers.add(1);
        integers.add(2);
        integers.add(3);
        integers.add(4);

        MyList myList = new MyList(integers);
        ArrayList<Integer> newArrayList = myList.getNewArrayList(new IOperate() {
            @Override
            public ArrayList operate(ArrayList<Integer> arrayList) {
                for (Integer i : arrayList) {
                    result.add(i * 10);
                }
                return result;
            }
        });

//        result.forEach(x-> System.out.println("x = " + x));

        for (Integer integer : result) {
            System.out.println("integer = " + integer);
        }
    }

}

 接口：

package lucas;

import java.util.ArrayList;

public interface IOperate {
    ArrayList<Integer> operate(ArrayList<Integer> arrayList);
}