Category：Blogs
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Time：2021-3-7
Before JDK7, switch can only support byte, short, char, int or their corresponding encapsulation classes and enum types. After JDK7, switch supports string type. In the switch statement, the value of the expression cannot be null, otherwise NullPointerException will be thrown at runtime. Null cannot be used in the case clause, otherwise compilation errors will […]
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Time：2021-3-7
Modules allow us to divide the code in the crates into groups to improve readability and reusability. The module also controls the privacy of the project, that is, whether the project can be used by external code (public) or internal implementation details but not for external use (private). For example, let’s write a library box […]
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Time：2021-3-7
introduce function App() { const [n, setN] = useState(0) const onClick = ()=>{ setN(n+1) Set n (n + 1) // at this time, we find that n can only + 1, not + 2 // setN(i=>i+1) // setN(i=>i+1) } return ( <div className=”App”> <h1>n: {n}</h1> <button onClick={onClick}>+2</button> </div> ); } ReactDOM.render(<App />, document.getElementById(“root”)); The react […]
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Time：2021-3-7
A series of articles： Let’s talk about the career planning of developers Talk about developer career planning 2 Talk about the choice of developer career planning industry and good company Talk about the team, position and income of developer career planning Talk about 520 special of developer career planning How to consider career development From […]
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Time：2021-3-7
Reluctance random access memoryMRAMIt is a new type of memory, which has the advantages of fast reading speed, high integration and non-volatile. At present, many researches focus on the application of MRAM in computer storage system. At the same time, nonvolatile MRAM memory is also used in all levels of cache. MRAM replaces SRAM as L2 […]
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Time：2021-3-7
Introduction of socket Socket, also known as “socket”, will send data through UDP / TCP protocol to realize simple communication between two machines. Note: if you want to use socket to realize simple communication between two machines, please make sure that the two machines are connected to the same local area network. Of course, socket […]
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Time：2021-3-7
A series of articles： Notes on Linux 1 Linux miscellany root file system Linux miscellany 2 /Boot system boot related, kernel, initrd, grub, boot loader This work adoptsCC agreementReprint must indicate the author and the link of this article The wind in June
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Time：2021-3-7
1.Model management: web online process designer, preview process XML, export XML, deploy process 2.Process management: import and export process resource file, view flow chart, reflect process model according to process instance, activate suspend、Free jump 3.Process in operation: view process information, current task node, current flow chart, void and suspend process, assign to-do person 4.The flow […]
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Time：2021-3-7
meaning: LEN Function returns the length of the value in a text field. Returns the number of characters in a character expression SQL LEN() grammar SELECT LEN(column_name) FROM table_name give an example: 1、LENReturn the same value for the same single byte and double byte string, such as Chinese character, English character, symbol. Note: lenWhen the […]
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Time：2021-3-7
If a Vue project is created from scratch with the scaffold vue-cli3, then don’t choose eslint when creating it. It’s really not easy to use. It’s to make the novice code more standardized. In fact, it’s to make your code have dozens of irrelevant errors all at once, and then you need to slowly modify […]
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Time：2021-3-7
Problem Description:There is a test server installed with Oracle11g (11.2.0.1), which runs normally in the morning. As a result, it can’t be accessed directly in the afternoon. It prompts an error: there is no monitor problem with ora-12541. Troubleshooting:According to the conventional method, restart the monitor program and database, and reconfigure the monitor program have […]
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Time：2021-3-7
import asyncio import time import numpy, random import pyppeteer async def main(): IP = “xxxxx” ා proxy IP Port =? XXX? Proxy port browser = await pyppeteer.launch({‘headless’: False, ‘args’: [ ‘–window-size={1300},{600}’ ‘–disable-extensions’, ‘–hide-scrollbars’, ‘–disable-bundled-ppapi-flash’, ‘–mute-audio’, ‘–no-sandbox’, ‘–disable-setuid-sandbox’, ‘–disable-gpu’, ‘–disable-infobars’ f’–proxy-server={ip}:{port}’ ], ‘dumpio’: True }) page = await browser.newPage Open a new page await page.goto (‘url […]
