Singleton mode

The simplest single instance mode was introduced yesterday. You can directly enter it from here: Singleton mode (1) Today, let’s continue to explore the single case model, or take the relationship between the universe, the earth and man as an example, You will find that the test result is that five different object addresses are printed, which suddenly destroys the principle of singleton object uniqueness. Let’s go on to review the code. Someone may find that every time we are return new Earth(); If you add an if judgment to…