用 Java 迭代列表中的两个元素

Question

Im looking for a way to iterate by two elements in Java

For example: i have this list: { "e1", "e2", "e3", "e4" }

and i want on first iteration get { "e1", "e2" }, on second { "e2", "e3" }

I have already find a way to do this with Python with itertools, like this:

import itertools
from itertools import tee

def pairwise(iterable):
    a, b = tee(iterable)
    next(b, None)
    return zip(a, b)

...
for e1,e2 in pairwise(list) :
    # creating an element using e1 and e2

I know i can do it manually in Java, but im asking is there's a defined way to do it, Thank you for your help

Answer 1

To achieve the task it's more then enough to use a regular loop and return on each step [curent,curent+1] list elements.

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

public class TestList
{
public static void main(String args[])
{
    ArrayList <String> l = new ArrayList(Arrays.asList("a","b","c","d"));
    List al = new TestList().iterateList(l);
    al.forEach(System.out::println);

}
public List iterateList(List l)
{

    ArrayList<String> al = new ArrayList();
    if(l==null || l.size() <= 1)
    {
        //list size should be not_null and greater then 1 : 2_fine
        return null;
    }
    for(int i=0;i<l.size()-1;i++)
    {
        String element = l.get(i)+","+l.get(i+1);
        al.add(element);
    }
    return al;
}

Output:
a,b
b,c
c,d

Answer 2

In Java, it is as simple as follows:

import java.util.List;

public class Main {
    public static void main(String[] args) {
        List<String> list = List.of("e1", "e2", "e3", "e4");
        for (int i = 0; i < list.size() - 1; i++) {
            System.out.println("(" + list.get(i) + ", " + list.get(i + 1) + ")");
        }
    }
}

Output:

(e1, e2)
(e2, e3)
(e3, e4)

Answer 3

After many searchs i think the only way in Java is to do it manually