This article is reproduced from: "Java regiment" official account.

1. Difference between object oriented and process oriented

Advantages of process oriented: the performance is higher than that of object-oriented, because class calls need to be instantiated, which costs a lot and consumes resources; For example, single chip microcomputer, embedded development and Linux / Unix generally adopt process oriented development, and performance is the most important factor. Disadvantages: there is no object-oriented, easy to maintain, easy to reuse and easy to expand. Object-oriented advantages: easy to maintain, easy to reuse and easy to expand. Because object-oriented has the characteristics of encapsulation, inheritance and polymorphism, it can design a low coupling system to make the system more flexible and easier to maintain. Disadvantages: the performance is lower than that of process oriented

翻译错误 TIMEOUT

3. The difference between overloading and rewriting

4. Can the constructor be overridden

5. The access control characters are public, protected, private, and default

7. Differences between string, StringBuffer and StringBuilder#

8. Relationship between hashcode and equals methods#

9. Differences between abstract classes and interfaces#

10. Automatic packing and unpacking#

11. What is generics, why are they used, and what are they#

12. Collection classes and relation diagrams in Java#

13. Implementation principle of HashMap#

14. Implementation principle of hashtable#

15. Differences between HashMap and hashtable#

16. Differences between ArrayList and vector#

17. Differences and usage scenarios between ArrayList and LinkedList#

18. Differences between collections and collections#

19. Implementation principle of concurrentashmap#

20. Difference between error and exception#

21.Unchecked

22. How to implement proxy mechanism in Java (JDK, cglib)#

23. Implementation of multithreading#

24. State transition of thread#