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May 20, 2022 Replied to a topic by agzou › Java › 请教一个 ConcurrentHashMap 问题 |
正如四楼大佬所说，contains 和 put 组合在一起就不是安全操作了
public class IdGeneratorService {
private final Map<String, AtomicLong> map = new ConcurrentHashMap<>();
public long nextId(String key) {
// 直接用这个方法
map.computeIfAbsent(key, it->new AtomicLong(0));
return map.get(key).incrementAndGet();
}
}
public class IdGeneratorService {
private final Map<String, AtomicLong> map = new ConcurrentHashMap<>();
public long nextId(String key) {
// 直接用这个方法
map.computeIfAbsent(key, it->new AtomicLong(0));
return map.get(key).incrementAndGet();
}
}
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