Java -从HashMap单键多值中获取键(反向映射)

import java.util.HashMap;
import java.util.Map;

public class ReverseHashMap {
    public static void main(String[] args) {
        // 创建原始的HashMap
        HashMap<String, String> originalMap = new HashMap<>();
        originalMap.put("key1", "value1");
        originalMap.put("key2", "value2");
        originalMap.put("key3", "value1");
        originalMap.put("key4", "value3");

        // 创建新的HashMap进行反向映射
        HashMap<String, String> reverseMap = new HashMap<>();
        for (Map.Entry<String, String> entry : originalMap.entrySet()) {
            String key = entry.getKey();
            String value = entry.getValue();
            if (reverseMap.containsKey(value)) {
                // 如果新HashMap中已存在该值，则将原始键与现有键拼接作为新值
                String newValue = reverseMap.get(value) + ", " + key;
                reverseMap.put(value, newValue);
            } else {
                // 否则直接将原始键作为新值
                reverseMap.put(value, key);
            }
        }

        // 根据值获取键的操作
        String targetValue = "value1";
        String targetKeys = reverseMap.get(targetValue);
        System.out.println("值为 " + targetValue + " 的键为：" + targetKeys);
    }
}