Are you just looking to document your code? if so The simplest and built right into the JDK is Javadoc.
Javadoc will parse the comments from your code along with the method names, classes etc and create a nice HTML structure for you. If you have ever read the Java API that was created using Javadoc.
Other then that if you want to look at writing your own program to show you the contents of a class, try using some tools from Java.
For example, the below code will take a JTextArea and print out to the user the methods which JTextArea defines and their corresponding parameters.
import java.lang.reflect.Method;
import java.lang.reflect.Type;
JTextArea myArea = new JTextArea();
Method[] methods = myArea.getClass().getDeclaredMethods();
for(int i=0; i<methods.length; i++){
System.out.println("Method Name:: " + methods[i].getName() );
System.out.println("Return Type:: " + methods[i].getReturnType());
Type[] params = method[i].getGenericParameterTypes();
for(int j=0; j<params.length; j++){
System.out.println("Parameter: " + params[j].toString());
}
}