Since multiple threads access and modify shared variables at the same time, it is easy to lead to data inconsistencies. To solve this problem, there are several ways to do it:
1.Use a lock mechanism.
In multithreaded programming, a locking mechanism can be used to ensure that only one thread can access a shared variable at a time. Both the synchronized keyword and the lock interface in j**a can implement the lock mechanism. By locking, you can ensure that only one thread can modify the value of a shared variable at a given time, thus avoiding uncertainty in the data.
2.Use the volatile keyword.
volatile is a keyword in j**a that allows variables to maintain visibility across multiple threads. When a shared variable is declared as volatile, it guarantees that the modified value is immediately updated to main memory, and when other threads need to read the variable, it reads the latest value in main memory. This avoids data inconsistencies due to caching.
3.Use atomic classes.
J**A provides atomic classes, such as atomicinteger, atomiclong, etc., which provide atomic operations to ensure the correctness of multi-threaded access to shared variables.
4.Use concurrent collection classes.
J**A provides concurrent collection classes, such as ConcurrentHashMap, CopyOnWriteArrayList, etc., which can be used safely in a multi-threaded environment. They use various locking mechanisms and data structures to ensure the correctness of multi-threaded access and avoid the problem of data uncertainty.
5.Avoid sharing variables.
If possible, try to avoid using shared variables to pass data. Communication between threads can be achieved by using thread local variables or by blocking queues, which can avoid data uncertainty.