使用接口将方法应用于 ArrayList [英] Using an interface to apply method to ArrayList

问题描述

我正在复习考试.旧测试中的一个问题是:使用接口编写一个方法，该方法将任意方法应用于 ArrayList 的每个元素.数组列表和方法都是方法的参数.

I'm reviewing for an exam. A question on an old test was to: Using an interface, write a method that applies an arbitrary method to every element of an ArrayList. Both the arraylist and method are the parameters to the method.

可行的解决方案是:

public <object> someMethod() {
    scanner GLaDOS = new (someArray);
    someArray.useDelimiter(",");
    for (i = 0; i < someArray.length; i++) {
        someOtherMethod(someArray[i]);
    }
}

推荐答案

我会期待这样的:

// define the interface to represent an arbitrary function
interface Function<T> {
    void Func(T el);
}

// now the method to apply an arbitrary function to the list
<T> void applyFunctionToArrayList(ArrayList<T> list, Function<T> func){
    // iterate over the list
    for(T item : list){
        // invoke the "arbitrary" function
        func.Func(item);
    }
}

<小时>

问题含糊不清，但这可能意味着返回一个新的 ArrayList，因此这可能是另一个可接受的答案

---

It's ambiguous in the question, but this might mean returning a new ArrayList, so this might be another acceptable answer

// define the interface to represent an arbitrary function
interface Function<T> {
    T Func(T el);
}

// now the method to apply an arbitrary function to the list
<T> ArrayList<T> applyFunctionToArrayList(ArrayList<T> list, Function<T> func){
    ArrayList<T> newList = new ArrayList<T>();

    // iterate over the list
    for(T item : list){
        // invoke the "arbitrary" function
        newList.add(func.Func(item));
    }
}

顺便说一句，您可以像这样调用应用程序(例如，将列表中的每个数字都加倍):

On a side note, you would then, say, invoke the application like (for example, doubling every number in the list):

ArrayList<Double> list = Arrays.asList(1.0, 2.0, 3.0);
ArrayList<Double> doubledList = applyFunctionToArrayList(list, 
  new Function<Double>{
    Double Func(Double x){
        return x * 2;
    }
});

这篇关于使用接口将方法应用于 ArrayList的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！