迭代conseecutive对象对在一个ArrayList [英] Iterate over conseecutive object pairs in an ArrayList

问题描述

我想对物体从一个ArrayList，所以我可以每个对象的元素之间进行计算。理想情况下，应该遍历对象对。例如，在一个列表{OBJ1，OBJ2，obj3，OBJ4}它应该通过{OBJ1，OBJ2}，{OBJ2，obj3}和{obj3，OBJ4}。

I want to get pairs of objects from an ArrayList so I can perform calculations between the elements of each object. Ideally it should iterate over pairs of objects. For example in a List with {obj1, obj2, obj3, obj4} it should go over {obj1,obj2}, {obj2,obj3} and {obj3,obj4}.

我已经试过到目前为止如下：

What I have tried so far is as follows.

public class Sum {
    public ArrayList<Double> calculateSum(ArrayList<Iter> iter) {
        ListIterator<Iter> it = iter.listIterator();
        ArrayList<Double> sums = new ArrayList<>();

        while (it.hasNext()) {
            Iter it1 = it.next();
            Iter it2;
            if(it.hasNext()){
                it2 = it.next();
            } else {    break;  }

            double sum = it1.getValue() + it2.getValue();
            sums.add(sum);
        }
        return sums;
    }
}

下面，它只是作为迭代{OBJ1，OBJ2}和{obj3，OBJ4}。我该如何解决这个问题？

Here, it just iterates as {obj1,obj2} and {obj3,obj4}. How can I fix this?

所有帮助是极大的AP preciated。谢谢！

All help is greatly appreciated. Thanks!

推荐答案

一个非常正常的循环，除非你需要循环到则为list.size（） - 1 ，在的前的最后的数组的元素。

A very normal loop, except that you need to loop up to list.size() - 1, the before last element of the array.

public ArrayList<Double> calculateSum(ArrayList<Iter> list) {
    ArrayList<Double> sums = new ArrayList<>();

    for (int i = 0; i < list.size() - 1; i++) {
        double sum = list.get(i).getValue() + list.get(i + 1).getValue();
        sums.add(sum);
    }
    return sums;
}

修改

在这种情况下，使用迭代器的的不的比做一个正常的循环更快，只是使逻辑过于复杂，很容易引入错误。

Using an iterator in this case will not be faster than doing a normal loop and just makes the logic unnecessarily complicated and can easily introduce bugs.

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