// make sure to use the Assistant v1 import!
import com.ibm.watson.assistant.v1.Assistant;

Authenticator authenticator = new IamAuthenticator("<iam_api_key>");
Assistant service = new Assistant("2019-02-28", authenticator);

MessageInput input = new MessageInput();
input.setText("Hi");
MessageOptions options = new MessageOptions.Builder(workspaceId)
  .input(input)
  .build();
MessageResponse response = service.message(options).execute().getResult();
System.out.println(response);

// make sure to use the Assistant v1 import!
import com.ibm.watson.assistant.v1.Assistant;

Context context = null;
MessageInput input = new MessageInput();

// first message
input.setText("First message");
MessageOptions newMessageOptions = new MessageOptions.Builder()
  .workspaceId("<workspace-id>")
  .input(input)
  .context(context)
  .build();

MessageResponse response = service.message(newMessageOptions).execute().getResult();
context = response.getContext();

// second message
input.setText("Second message");
newMessageOptions = new MessageOptions.Builder()
  .workspaceId("<workspace-id>")
  .input(input)
  .context(context) // using context from the first message
  .build();

response = service.message(newMessageOptions).execute().getResult();

System.out.println(response);

// make sure to use the Assistant v2 import!
import com.ibm.watson.assistant.v2.Assistant;

Authenticator authenticator = new IamAuthenticator("<iam_api_key>");
Assistant service = new Assistant("2019-02-28", authenticator);

MessageInput input = new MessageInput.Builder()
  .text("Hi")
  .build();
MessageOptions messageOptions = new MessageOptions.Builder()
  .assistantId("<assistant_id>")
  .sessionId("<session_id>")
  .input(input)
  .build();
MessageResponse messageResponse = service.message(messageOptions).execute().getResult();

System.out.println(messageResponse);

// make sure to use the Assistant v2 import!
import com.ibm.watson.assistant.v2.Assistant;

MessageContext context = new MessageContext();

// first message
MessageInput input = new MessageInput.Builder()
  .text("First message")
  .build();
MessageOptions messageOptions = new MessageOptions.Builder()
  .assistantId(assistantId)
  .sessionId(sessionId)
  .input(input)
  .context(context)
  .build();

MessageResponse messageResponse = service.message(messageOptions).execute().getResult();
context = messageResponse.getContext();

// second message
input = new MessageInput.Builder()
  .text("Second message")
  .build();
messageOptions = new MessageOptions.Builder()
  .assistantId(assistantId)
  .sessionId(sessionId)
  .input(input)
  .context(context) // using context from first message
  .build();

messageResponse = service.message(messageOptions).execute().getResult();

System.out.println(messageResponse);