Java 8中如何智能去除List<T>中的连续重复元素？

我太懂这种需求了！常规的distinct()或者转Set完全不顶用——它们是全局去重，根本解决不了“只移除连续相邻重复元素”的场景。刚好Java 8的Stream或者增强库StreamEx能给出简洁可读的解决方案，给你分享两种靠谱思路：

方案一：纯Java 8原生Stream实现 #

原生Stream本身没有直接处理状态的操作，但我们可以借助Collectors.collectingAndThen结合遍历逻辑来实现，完全不用额外依赖：

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

public class ConsecutiveDuplicateHandler {
    public static <T> List<T> removeConsecutiveDuplicates(List<T> inputList) {
        if (inputList == null || inputList.isEmpty()) {
            return new ArrayList<>();
        }
        
        return inputList.stream()
                .collect(Collectors.collectingAndThen(
                        Collectors.toList(),
                        collectedList -> {
                            List<T> result = new ArrayList<>();
                            T previous = null;
                            
                            for (T current : collectedList) {
                                // 仅当当前元素和上一个不同时，才加入结果集
                                if (previous == null || !current.equals(previous)) {
                                    result.add(current);
                                    previous = current;
                                }
                            }
                            return result;
                        }
                ));
    }

    public static void main(String[] args) {
        List<String> original = List.of("A","A","A","B","B","A","A","A","C","C","C","A","A","B","B","A");
        List<String> cleaned = removeConsecutiveDuplicates(original);
        System.out.println(cleaned); // 输出: [A, B, A, C, A, B, A]
    }
}

这个方案的逻辑非常直白：先把所有元素收集到List，再遍历的时候只保留和前一个元素不同的项，完全用原生API就能实现，不用引入任何第三方库。

方案二：用StreamEx实现（极致简洁） #

如果你项目里已经引入了StreamEx（Java Stream的增强库），那这个问题一行代码就能搞定——StreamEx专门提供了dedup()方法，默认就是移除连续相邻的重复元素：

首先先引入StreamEx的依赖（以Maven为例）：

<dependency>
    <groupId>one.util</groupId>
    <artifactId>streamex</artifactId>
    <version>0.8.1</version>
</dependency>

然后实现代码：

import one.util.streamex.StreamEx;
import java.util.List;

public class ConsecutiveDuplicateHandler {
    public static void main(String[] args) {
        List<String> original = List.of("A","A","A","B","B","A","A","A","C","C","C","A","A","B","B","A");
        List<String> cleaned = StreamEx.of(original)
                .dedup()
                .toList();
        
        System.out.println(cleaned); // 输出: [A, B, A, C, A, B, A]
    }
}

dedup()方法内部已经封装了连续重复的判断逻辑，代码简洁到爆炸，可读性拉满。而且它还支持自定义重复判断规则，比如忽略大小写的连续去重：

// 示例：忽略大小写的连续重复移除
List<String> caseInsensitiveCleaned = StreamEx.of(original)
        .dedup(String::equalsIgnoreCase)
        .toList();

内容的提问来源于stack exchange，提问作者Mbded