ObjectAnalyzer

package objectAnalyzer;
import java.util.ArrayList;
/**
* This program uses reflection to spy on objects.
* @version 1.12 2012-01-26
* @author Cay Horstmann
*/
public class ObjectAnalyzerTest
{
public static void main(String[] args)
{
ArrayList<Integer> squares = new ArrayList<>();
for (int i = 1; i <= 5; i++)
squares.add(i * i);
System.out.println(new ObjectAnalyzer().toString(squares));
}
}

package objectAnalyzer;
import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Array;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
public class ObjectAnalyzer
{
private ArrayList<Object> visited = new ArrayList<>();
/**
* 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;
}
}