输出lambda表达式

Question

由于Interface IArea中的参数Map

，我输出结果时遇到了麻烦

public class Lambda {

    public static void main(String[] args) {

        double x=10,y=8,pi=3.14159265359,radius=7;
        IArea triangle = (Map<ShapeProperties, Double> props) -> {
        props.put(ShapeProperties.base, x);
        props.put(ShapeProperties.height, y); 
        return (props.get(ShapeProperties.base) * 
        props.get(ShapeProperties.height) / 2);
        };

    IArea rectangle = (Map<ShapeProperties, Double> props) -> {
        props.put(ShapeProperties.width, x);
        props.put(ShapeProperties.length, y); 
        return (props.get(ShapeProperties.base) * 
        props.get(ShapeProperties.height));
        };

    IArea circle = (Map<ShapeProperties, Double> props) -> {
        props.put(ShapeProperties.radius, radius);
        return (pi*Math.pow(props.get(ShapeProperties.radius),2));
        };

  //this is the part where the error occurs.
    System.out.println(triangle.getArea(Map<ShapeProperties, Double> 
    props));
}   
}

有人可以指导我如何处理本练习的输出部分？提前谢谢。

Answer 1

这是我的解决方案：

System.out.println(triangle.getArea(new HashMap<>()));

关键是您需要将Map对象传递给triangle.getArea（）