import java.lang.reflect.*; import java.util.*; /** * This program uses reflection to spy on objects. * @version 1.11 2004-02-21 * @author Cay Horstmann */ public class ObjectAnalyzerTest { public static void main(String[] args) { ArrayList squares = new ArrayList(); for (int i = 1; i <= 5; i++) squares.add(i * i); System.out.println(new ObjectAnalyzer().toString(squares)); } } class ObjectAnalyzer { /** * Converts an object to a string representation that lists all fields. * @param obj an object * @return a string with the object's class name and all field names and * values */ public String toString(Object obj) { if (obj == null) return "null"; if (visited.contains(obj)) return "..."; visited.add(obj); Class cl = obj.getClass(); if (cl == String.class) return (String) obj; if (cl.isArray()) { String r = cl.getComponentType() + "[]{"; for (int i = 0; i < Array.getLength(obj); i++) { if (i > 0) r += ","; Object val = Array.get(obj, i); if (cl.getComponentType().isPrimitive()) r += val; else r += toString(val); } return r + "}"; } String r = cl.getName(); // inspect the fields of this class and all superclasses do { r += "["; Field[] fields = cl.getDeclaredFields(); AccessibleObject.setAccessible(fields, true); // get the names and values of all fields for (Field f : fields) { if (!Modifier.isStatic(f.getModifiers())) { if (!r.endsWith("[")) r += ","; r += f.getName() + "="; try { Class t = f.getType(); Object val = f.get(obj); if (t.isPrimitive()) r += val; else r += toString(val); } catch (Exception e) { e.printStackTrace(); } } } r += "]"; cl = cl.getSuperclass(); } while (cl != null); return r; } private ArrayList visited = new ArrayList(); }