如何在主线程中获得异步结果

def async_operation(callback):
    # 异步操作
    result = "异步结果"
    callback(result)

def main():
    def callback(result):
        print("异步结果已获取：", result)

    async_operation(callback)

if __name__ == "__main__":
    main()

function asyncOperation() {
    return new Promise((resolve, reject) => {
        // 异步操作
        const result = "异步结果";
        resolve(result);
    });
}

async function main() {
    const result = await asyncOperation();
    console.log("异步结果已获取：", result);
}

main();

async function asyncOperation() {
    // 异步操作
    const result = "异步结果";
    return result;
}

async function main() {
    const result = await asyncOperation();
    console.log("异步结果已获取：", result);
}

main();

import java.util.concurrent.*;

public class Main {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        Future<String> future = asyncOperation();
        String result = future.get();
        System.out.println("异步结果已获取：" + result);
    }

    public static Future<String> asyncOperation() {
        ExecutorService executor = Executors.newSingleThreadExecutor();
        Future<String> future = executor.submit(() -> {
            // 异步操作
            String result = "异步结果";
            return result;
        });
        executor.shutdown();
        return future;
    }
}