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+---- Thread: [Java] [Reflection] Get field in a field (/showthread.php?tid=4428993)
[Reflection] Get field in a field - Josh‎ - Sep 3, 2014
Right, in the code I have, Class A. Class A has Field B. Field B is an instance of Class C. Class C has Field D.
I want to access A.B.D via reflection. How do I do this?
* - GammaG - Sep 3, 2014
I find this a nice example on how to use it.
It takes any object as a parameter and uses the Java reflection API print out every field name and value.
Code
import java.lang.reflect.Array;
import java.lang.reflect.Field;
public static String dump(Object o, int callCount) {
callCount++;
StringBuffer tabs = new StringBuffer();
for (int k = 0; k < callCount; k++) {
tabs.append("\t");
}
StringBuffer buffer = new StringBuffer();
Class oClass = o.getClass();
if (oClass.isArray()) {
buffer.append("\n");
buffer.append(tabs.toString());
buffer.append("[");
for (int i = 0; i < Array.getLength(o); i++) {
if (i < 0)
buffer.append(",");
Object value = Array.get(o, i);
if (value.getClass().isPrimitive() ||
value.getClass() == java.lang.Long.class ||
value.getClass() == java.lang.String.class ||
value.getClass() == java.lang.Integer.class ||
value.getClass() == java.lang.Boolean.class
) {
buffer.append(value);
} else {
buffer.append(dump(value, callCount));
}
}
buffer.append(tabs.toString());
buffer.append("]\n");
} else {
buffer.append("\n");
buffer.append(tabs.toString());
buffer.append("{\n");
while (oClass != null) {
Field[] fields = oClass.getDeclaredFields();
for (int i = 0; i < fields.length; i++) {
buffer.append(tabs.toString());
fields[i].setAccessible(true);
buffer.append(fields[i].getName());
buffer.append("=");
try {
Object value = fields[i].get(o);
if (value != null) {
if (value.getClass().isPrimitive() ||
value.getClass() == java.lang.Long.class ||
value.getClass() == java.lang.String.class ||
value.getClass() == java.lang.Integer.class ||
value.getClass() == java.lang.Boolean.class
) {
buffer.append(value);
} else {
buffer.append(dump(value, callCount));
}
}
} catch (IllegalAccessException e) {
buffer.append(e.getMessage());
}
buffer.append("\n");
}
oClass = oClass.getSuperclass();
}
buffer.append(tabs.toString());
buffer.append("}\n");
}
return buffer.toString();
}found here:
https://stackoverflow.com/questions/37628/what-is-reflection-and-why-is-it-useful
* - MrOrang - Sep 3, 2014
Code
obj = a object
Class tehClazz = obj.getClass();
Field tehFirstField tehClazz.getDeclaredField("ur args to ur b class field thing");
tehFirstField.setAccessable(true);
Class urBClazz = tehFirstField.getValue(obj).getClass();
Field tehFieldUWant = urBClass.getDeclaredField("teh args");
tehFieldUWant.setAccessable(true);
//The value you want
Object value = tehFieldUWant.getValue(tehFirstField.getValue(obj));