Loop Agents in ADK Java — The Basic While-Loop Pattern

The basic shape

public AgentResponse runLoop(String task, int maxIterations) {
  String current = task;
  for (int i = 0; i < maxIterations; i++) {
    AgentResponse resp = agent.invoke(current);
    if (isDone(resp)) {
      return resp;
    }
    current = resp.text();
  }
  throw new LoopExhaustedException(maxIterations);
}

Deciding 'done'

The stopping condition can be model-driven ('does the agent say STOP?') or external ('does the output pass validation?'). External is more reliable — models forget to say STOP.

Always cap iterations

Never write an unbounded while(true) agent loop. Cap at 5-10 for most cases. Log when the cap is hit — that's diagnostic gold.