How can Java achieve high concurrency?

Several methods can be used in Java to achieve high concurrency.

1. Utilizing a thread pool: manage threads through a thread pool to avoid the overhead of frequently creating and destroying threads.
2. Utilizing multithreading technology: splitting tasks into multiple subtasks and executing them simultaneously to enhance concurrency performance.
3. Using non-blocking IO technology: In network programming, utilizing non-blocking IO technology can reduce the time spent waiting for threads to unblock, thereby enhancing concurrent performance.
4. Using a message queue: by writing requests to a message queue and having multiple consumers process them, the processing time for requests is reduced and concurrency performance is improved.
5. Use distributed cache: store hot data in distributed cache to reduce access to the database, thus improving concurrent performance.
6. Using distributed locks: In cases of concurrent operations in multiple threads, distributed locks are used to ensure data consistency and thread safety.

The above are some commonly used methods, the specific implementation needs to be chosen and optimized based on the specific business scenario.