当列表通过For循环返回时，无法在Java中将列表转换为Map

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class ListToMapExample {
    public static void main(String[] args) {
        List<String> list = new ArrayList<>();
        list.add("key1");
        list.add("value1");
        list.add("key2");
        list.add("value2");

        Map<String, String> map = new HashMap<>();
        for (int i = 0; i < list.size(); i += 2) {
            String key = list.get(i);
            String value = list.get(i + 1);
            map.put(key, value);
        }

        System.out.println(map);
    }
}