Utils

from https://github.com/ros2java-alfred/ros2_java_utils

Nodes

$ ros2nodes_java 

Topics

$ ros2topics_java 
ros2topic_java is a command-line tool for printing information about ROS Topics.
Commands:
	ros2topic_java echo	print messages to screen
	ros2topic_java find	find topics by type
	ros2topic_java hz	display publishing rate of topic    
	ros2topic_java list	list active topics
	ros2topic_java pub	publish data to topic
	ros2topic_java type	print topic type
Type ros2topic_java <command> -h for more detailed usage, e.g. 'ros2topic echo -h'

Services

$ ros2services_java 
ros2service_java is a command-line tool for printing information about ROS Services.
Commands:
	ros2service_java find	find service by type
	ros2service_java list	list active services
	ros2service_java req	request data to service
	ros2service_java type	print service type
Type ros2service_java <command> -h for more detailed usage, e.g. 'ros2service_java echo -h'

Parameters

From rclcpp package

$ ros2param list