The below code can be used to Publish Custom Metrics in AWS CloudWatch using JAVA.
AmazonCloudWatch amazonCloudWatch =
AmazonCloudWatchClientBuilder.standard().withEndpointConfiguration(
new AwsClientBuilder.EndpointConfiguration("monitoring.us-west-1.amazonaws.com","us-west-1")).build();
PutMetricDataRequest putMetricDataRequest = new PutMetricDataRequest();
putMetricDataRequest.setNamespace("CUSTOM/SQS");
MetricDatum metricDatum1 = new MetricDatum().withMetricName("MessageCount").withDimensions(new Dimension().withName("Personalization").withValue("123"));
metricDatum1.setValue(-1.00);
metricDatum1.setUnit(StandardUnit.Count);
putMetricDataRequest.getMetricData().add(metricDatum1);
PutMetricDataResult result = amazonCloudWatch.putMetricData(putMetricDataRequest);
Only thing to remember is to include aws-java-sdk-cloudwatch