1) S3 Connection :
AmazonS3ClientBuilder
.standard()
.withEndpointConfiguration(new EndpointConfiguration("http://localhost:4566/", "us-east-1")) // localstack endpoint configuration
.withCredentials(new DefaultAWSCredentialsProviderChain())
.withPathStyleAccessEnabled(true) // Disable virtualhost style connection and enable path style s3 bucket
.build();

2) SQS Connection :
AmazonSQSClientBuilder.standard()
.withEndpointConfiguration(new EndpointConfiguration("http://localhost:4566", "us-east-1"))
.withCredentials(new DefaultAWSCredentialsProviderChain());

3) SNS Connection : 
 AmazonSNSClientBuilder.standard()
  .withEndpointConfiguration(new EndpointConfiguration("http://localhost:4575", "eu-west-1")) 
  .build();