Java Source code for Reflection to Spy on Objects

Reflection to Spy on Objects

import java.lang.reflect.*;

import java.util.*;

/**

* This program uses reflection to spy on objects.

*/

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 <>

{

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

}

<< Back == Next >>