The settings.json file is located in the user-level or workspace-level path and is used to customize VSCode settings. 1. User-level path: Windows is C:\Users\\AppData\Roaming\Code\User\settings.json, macOS is /Users//Library/ApplicationSupport/Code/User/settings.json, Linux is /home//.config/Code/User/settings.json; 2. Workspace-level path: .vscode/settings in the project root directory

To correctly handle JDBC transactions, you must first turn off the automatic commit mode, then perform multiple operations, and finally commit or rollback according to the results; 1. Call conn.setAutoCommit(false) to start the transaction; 2. Execute multiple SQL operations, such as INSERT and UPDATE; 3. Call conn.commit() if all operations are successful, and call conn.rollback() if an exception occurs to ensure data consistency; at the same time, try-with-resources should be used to manage resources, properly handle exceptions and close connections to avoid connection leakage; in addition, it is recommended to use connection pools and set save points to achieve partial rollback, and keep transactions as short as possible to improve performance.

itertools.combinations is used to generate all non-repetitive combinations (order irrelevant) that selects a specified number of elements from the iterable object. Its usage includes: 1. Select 2 element combinations from the list, such as ('A','B'), ('A','C'), etc., to avoid repeated order; 2. Take 3 character combinations of strings, such as "abc" and "abd", which are suitable for subsequence generation; 3. Find the combinations where the sum of two numbers is equal to the target value, such as 1 5=6, simplify the double loop logic; the difference between combinations and arrangement lies in whether the order is important, combinations regard AB and BA as the same, while permutations are regarded as different;

DependencyInjection(DI)isadesignpatternwhereobjectsreceivedependenciesexternally,promotingloosecouplingandeasiertestingthroughconstructor,setter,orfieldinjection.2.SpringFrameworkusesannotationslike@Component,@Service,and@AutowiredwithJava-basedconfi

There are four main ways to obtain BTC: 1. Register and exchange it with fiat currency or other digital assets through centralized trading platforms such as Binance, OK, Huobi, and Gate.io; 2. Participate in P2P platforms to directly trade with individuals, and pay attention to the credit risks of the counterparty; 3. Provide goods or services to accept BTC as payment; 4. Participate in airdrops, competitions and other platform reward activities to obtain a small amount of BTC. The core difference between BTC and digital currency is: 1. BTC is a type of digital currency, which belongs to a genus relationship; 2. BTC adopts a proof of work (PoW) mechanism, while other digital currencies may use various technologies such as proof of stake (PoS); 3. BTC emphasizes the value storage function of "digital gold", and other digital currencies may focus on payment efficiency or

Use classes in the java.time package to replace the old Date and Calendar classes; 2. Get the current date and time through LocalDate, LocalDateTime and LocalTime; 3. Create a specific date and time using the of() method; 4. Use the plus/minus method to immutably increase and decrease the time; 5. Use ZonedDateTime and ZoneId to process the time zone; 6. Format and parse date strings through DateTimeFormatter; 7. Use Instant to be compatible with the old date types when necessary; date processing in modern Java should give priority to using java.timeAPI, which provides clear, immutable and linear

TheJVMenablesJava’s"writeonce,runanywhere"capabilitybyexecutingbytecodethroughfourmaincomponents:1.TheClassLoaderSubsystemloads,links,andinitializes.classfilesusingbootstrap,extension,andapplicationclassloaders,ensuringsecureandlazyclassloa

The difference between cryptocurrencies and stocks lies in the nature of assets, market mechanisms and risk-return characteristics. 1. Stocks represent corporate ownership, value is based on profits and dividends, regulated and trading time is limited, with an annualized return of about 10%, suitable for medium- and long-term investors; 2. Cryptocurrencies rely on market consensus and technology applications, with 24-hour trading, no limit on fluctuations, and volatility is severe. Bitcoin’s historical average annual return reaches 46.6%, but the drawdown is often more than 80%, which is even higher; 3. Conservative investors should allocate 70-80% stocks 20-30% cryptocurrency fixed investment, and radicals can invest in crypto assets mainly and use stablecoins and AI tools to hedge risks; 4. The optimal strategy in 2025 is to build a combination of "stock ballast (70%) cryptocurrency commando (30%)".