java为什么会出现找不到符号错误？

Question

import java.util.ArrayList;
import java.util.List;

public class NestedListEg1 {
    public static void main(String[] args) {
        
        List<List<Money>> outerList = new ArrayList<List<Money>>();
        
        List<Money> innerList = new ArrayList<Money>();
        
        innerList.add(new Money(Currency.USD, 100));
        outerList.add(innerList);
        
        
        System.out.println("outerList = "+outerList);
    }
}

Answer 1

你需要进口货币