package horstmann.ch07_reflect2;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Random;

/**
   This program shows how to use reflection to print
   the names and values of all nonstatic fields of an object.
 */
public class FieldTester
{
	public static void main(String[] args)
			throws IllegalAccessException
	{
		Random r = new Random();
		System.out.print(spyFields(r));
		r.nextInt();
		System.out.println("\nAfter calling nextInt:\n");
		System.out.print(spyFields(r));
	}

	/**
      Spies on the field names and values of an object.
      @param obj the object whose fields to format
      @return a string containing the names and values of
      all fields of obj
	 */
	public static String spyFields(Object obj)
			throws IllegalAccessException
	{
		StringBuilder buffer = new StringBuilder();
		Field[] fields = obj.getClass().getDeclaredFields();
		for (Field f : fields)
		{
			if (!Modifier.isStatic(f.getModifiers()))
			{
				f.setAccessible(true);
				Object value = f.get(obj);
				buffer.append(f.getType().getName());
				buffer.append(" ");
				buffer.append(f.getName());
				buffer.append("=");
				buffer.append("" + value);
				buffer.append("\n");
			}
		}
		return buffer.toString();
	}
}