void lock()

Acquires the lock.

If the lock is not available then the current thread becomes disabled for thread scheduling purposes and lies dormant until the

lock has been acquired.

Implementation Considerations ：A Lock implementation may be able to detect erroneous use of the lock, such as an invocation

that would cause deadlock, and may throw an (unchecked) exception in such circumstances. The circumstances and the exception

type must be documented by that Lock implementation.

boolean tryLock()

Acquires the lock only if it is free at the time of invocation.

Acquires the lock if it is available and returns immediately with the value true. If the lock is not available then this method will

return immediately with the value false.

A typical usage idiom for this method would be:

      Lock lock = ...;      if (lock.tryLock()) {          try {              // manipulate protected state          } finally {              lock.unlock();          }      } else {          // perform alternative actions      }

This usage ensures that the lock is unlocked if it was acquired, and doesn‘t try to unlock if the lock was not acquired.

tryLock & lock 区别