A class is said to be Immutable if its state cannot be changed once created, for example, String in Java is immutable. Once you create a String say "Java", you cannot change its content. Any modification in this string e.g. converting into upper case, concatenating with another String will

process 跟 thread 到底有什麼不同呢? 簡單的說，process 跟 process 之間的記憶體 (memory)是不共享的，而 thread 跟 thread 之間的記憶體是共享的