Java将超类类型的对象指向适当的方法

Question

In my Java code I have a class 'Feature' which is extended by 'ContinuousFeature' and 'DiscreteFeature'. I have methods:

Calculate(ContinuousFeature c)

and

Calculate(DiscreteFeature d)

I have an ArrayList containing generic 'Feature' objects (both Discrete and Continuous), and am trying to do something like:

for(Feature f : features) {

    Calculate(f);

}

Hoping that they would automatically be directed to the appropriate method. However, IntelliJ is informing me that it cannot find a method Calculate for type 'Feature'. Any advice? :)

Answer 1

You can change code like this.

for(Feature f : features) {
if(f instanceof ContinuousFeature)
    Calculate((ContinuousFeature)f);
else {
 Calculate((DiscreteFeature)f);
}

}

Answer 2

如果你不喜欢使用instanceof ，我建议在它们各自的类中添加像isContinuousFeature()这样的方法，返回一个布尔类型并每次检查，它可能不是最干净的，但它会得到你想要的。

Answer 3

You could create in your Feature.java something like

public void Calculate(Feature feature){}

And I think that line could solve your problem. Or maybe make the class abstract and something like:

public abstract void Calculate(Feature feature);

would be enough. And I think it would be cleaner. But that's just my opinion. Hope this helps.