如何在while循环中初始化对象

Question

我正在尝试初始化对象直到成功。该代码工作正常，但不适用于第一个实例/迭代。有没有办法在 while 循环中初始化对象？

V1NamespaceList listOfns = null;
try {
    listOfns = api.listNamespace(null, true, null, null, null, null, null, null, null, null);
} catch (Exception e) {
    System.out.println("Something went wrong while fetching namespace list. Trying again ");
    while (listOfns != null)
    {
        listOfns = api.listNamespace(null, true, null, null, null, null, null, null, null, null);
    }
}

我的目标是尝试直到

listOfns

对象初始化成功。我怎样才能实现这一目标？

Answer 1

我建议在程序中添加重试次数。如果程序继续失败，您应该排除出现问题的原因。除非真的有特殊需要。

V1NamespaceList listOfNs = null;
int retryCount = 0;
final int MAX_RETRIES = 5; 
while (retryCount < MAX_RETRIES) {
    try {
        listOfNs = api.listNamespace(null, true, null, null, null, null, 
null, null, null, null);
        if (listOfNs != null) {
            break; 
        }
    } catch (Exception e) {
        System.out.println("Something went wrong while fetching namespace list. Trying again. Retry #" + (retryCount + 1));

    }
 retryCount++;

// can sleep for a while
 
//try {
//   Thread.sleep(1000);  
//} catch (InterruptedException ie) {
//    Thread.currentThread().interrupt();  
//}
   
}

if (listOfNs == null) {
    System.out.println("Failed to fetch namespace list after " + MAX_RETRIES + " attempts.");

// TODO

}

Answer 2

这就是 spring-retry 可以发挥作用的地方。只需根据您的喜好配置 retryTemplate 即可。

RetryTemplate retryTemplate = RetryTemplate.builder().infiniteRetry()
        .exponentialBackoff(Duration.ofMillis(100), 2, Duration.ofSeconds(5)).build();
String listOfNs = retryTemplate.execute(context -> {
    log.info("RetryNo: {}", context.getRetryCount());
    // return api.listNamespace(....)
    return "Hello World!";
});
log.info("Retry: {}", listOfNs);