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

fixture is a function used to provide preset environment or data for tests. 1. Use the @pytest.fixture decorator to define fixture; 2. Inject fixture in parameter form in the test function; 3. Execute setup before yield, and then teardown; 4. Control scope through scope parameters, such as function, module, etc.; 5. Place the shared fixture in conftest.py to achieve cross-file sharing, thereby improving the maintainability and reusability of tests.

Beginners should give priority to spot trading. 1. Spot trading is a way to buy and sell instantly and complete delivery. After buying, you actually own digital assets, which is relatively low risk and is suitable for beginners; 2. Contract trading speculates in future prices through leverage. Although it may amplify returns, it also greatly increases the risk of loss, which is suitable for experienced traders; 3. Pre-market trading is an off-market pre-order before the new token is launched. It has great opportunities but poor liquidity and high risk, so it requires strong identification ability; 4. Therefore, novices should first be familiar with the market through spot trading, accumulate experience, and then try contract trading carefully to avoid participating in high-risk pre-market trading to achieve a stable start.

In the digital asset derivatives market, contract trading is one of the core ways to play, and understanding different margin types is the first lesson for beginners. Choosing USDT, USDC, or currency standard contracts is directly related to your income calculation method and risk exposure. Understanding their differences will allow you to make better decisions in market fluctuations. If you have higher requirements for the compliance and transparency of funds, then choosing a USDC-based contract supported by large platforms such as Ouyi OKX and Binance will make you feel more at ease.