How should i get aws region names using regions

There isn't an AWS API method to call to get this information.

Some SDKs, such as the AWS SDK for .NET has this information baked into the SDK. For example, in C#:

var regions = Amazon.RegionEndpoint.EnumerableAllRegions;
foreach (var r in regions)
{
  Console.WriteLine("{0} -> {1}", r.SystemName, r.DisplayName);
}

Looking through the docs for the AWS SDK for Java, I am not finding an equivalent. If it were there, I would think it should be on the com.amazonaws.regions.Region class.

You may have to create your own mapping.