public Integer getPeriod() {
        return this.period;
    }
<p>
The length, in seconds, used each time the metric specified in <code>MetricName</code> is evaluated. Valid values
are 10, 30, and any multiple of 60.
</p>
<p>
<code>Period</code> is required for alarms based on static thresholds. If you are creating an alarm based on a
metric math expression, you specify the period for each metric within the objects in the <code>Metrics</code>
array.
</p>
<p>
Be sure to specify 10 or 30 only for metrics that are stored by a <code>PutMetricData</code> call with a
<code>StorageResolution</code> of 1. If you specify a period of 10 or 30 for a metric that does not have
sub-minute resolution, the alarm still attempts to gather data at the period rate that you specify. In this case,
it does not receive data for the attempts that do not correspond to a one-minute data resolution, and the alarm
might often lapse into INSUFFICENT_DATA status. Specifying 10 or 30 also sets this alarm as a high-resolution
alarm, which has a higher charge than other alarms. For more information about pricing, see <a
href="https://aws.amazon.com/cloudwatch/pricing/">Amazon CloudWatch Pricing</a>.
</p>
<p>
An alarm's total current evaluation period can be no longer than one day, so <code>Period</code> multiplied by
<code>EvaluationPeriods</code> cannot be more than 86,400 seconds.
</p>

@return The length, in seconds, used each time the metric specified in <code>MetricName</code> is evaluated.
        Valid values are 10, 30, and any multiple of 60.</p>
        <p>
        <code>Period</code> is required for alarms based on static thresholds. If you are creating an alarm based
        on a metric math expression, you specify the period for each metric within the objects in the
        <code>Metrics</code> array.
        </p>
        <p>
        Be sure to specify 10 or 30 only for metrics that are stored by a <code>PutMetricData</code> call with a
        <code>StorageResolution</code> of 1. If you specify a period of 10 or 30 for a metric that does not have
        sub-minute resolution, the alarm still attempts to gather data at the period rate that you specify. In
        this case, it does not receive data for the attempts that do not correspond to a one-minute data
        resolution, and the alarm might often lapse into INSUFFICENT_DATA status. Specifying 10 or 30 also sets
        this alarm as a high-resolution alarm, which has a higher charge than other alarms. For more information
        about pricing, see <a href="https://aws.amazon.com/cloudwatch/pricing/">Amazon CloudWatch Pricing</a>.
        </p>
        <p>
        An alarm's total current evaluation period can be no longer than one day, so <code>Period</code>
        multiplied by <code>EvaluationPeriods</code> cannot be more than 86,400 seconds.
aws-java-sdk-cloudwatch/src/main/java/com/amazonaws/services/cloudwatch/model/PutMetricAlarmRequest.java