如何避免枚举（Enum）使用过程中抛出NullPointerException空指针异常

数据老陈

2026-9-26

问题根因

空指针异常并非出自orNull()后的匹配逻辑，Guava的Enums.getIfPresent方法对输入的查找字符串有强制非空校验，当传入的mood为null时，方法内部会先抛出NPE，根本不会执行到后续的orNull()以及匹配逻辑。

修复方案

优先对入参mood做非空、非空白校验，无效值直接返回false，避免进入后续枚举查找逻辑
优化判断逻辑：先统一转换得到枚举实例，再用Set的contains方法直接判断，无需遍历流重复执行枚举查找，性能更优

修复后代码

import com.google.common.base.Enums;
import com.google.common.base.Strings;
import com.google.common.collect.Sets;
import java.util.Set;

public enum KnowYourMoodEnum {
    ANGRY, SAD, HAPPY, FEELING_GOOD;
    
    private static final Set<KnowYourMoodEnum> HAPPY_MOOD_LIST = Sets.newHashSet(HAPPY, FEELING_GOOD);
    private static final Set<KnowYourMoodEnum> UPSET_MOOD_LIST = Sets.newHashSet(ANGRY, SAD);
    
    public static boolean isHappyMood(String mood) {
        // 入参无效直接返回false，也可自行替换为原生非空判断：if (mood == null || mood.isEmpty())
        if (Strings.isNullOrEmpty(mood)) {
            return false;
        }
        KnowYourMoodEnum targetMood = Enums.getIfPresent(KnowYourMoodEnum.class, mood).orNull();
        return targetMood != null && HAPPY_MOOD_LIST.contains(targetMood);
    }
    
    public static boolean isUpsetMood(String mood) {
        if (Strings.isNullOrEmpty(mood)) {
            return false;
        }
        KnowYourMoodEnum targetMood = Enums.getIfPresent(KnowYourMoodEnum.class, mood).orNull();
        return targetMood != null && UPSET_MOOD_LIST.contains(targetMood);
    }
    
}