what is retry policy in android? code example

Example: android retry pollicy

/**
 * Attempts to prepare the request for a retry. If there are no more attempts remaining in the
 * request's retry policy, a timeout exception is thrown.
 * @param request The request to use.
 */
protected static void attemptRetryOnException(String logPrefix, Request<?> request, VolleyError exception) throws VolleyError {
    RetryPolicy retryPolicy = request.getRetryPolicy();
    int oldTimeout = request.getTimeoutMs();

    try {
        retryPolicy.retry(exception);
    } catch (VolleyError e) {
        request.addMarker(String.format("%s-timeout-giveup [timeout=%s]", logPrefix, oldTimeout));
        throw e;
    }
    request.addMarker(String.format("%s-retry [timeout=%s]", logPrefix, oldTimeout));

    //reentry the requestQueue
    RequestQueue requestQueue = getRequestQueue(request);
    if (requestQueue != null) {
        requestQueue.add(request);
    }

    throw new RetryError();
}