I have a class with a private static final
field that, unfortunately, I need to change it at run-time.
Using reflection I get this error: java.lan
Just saw that question on one of the interview question, if possible to change final variable with reflection or in runtime. Got really interested, so that what I became with:
/**
* @author Dmitrijs Lobanovskis
* @since 03/03/2016.
*/
public class SomeClass {
private final String str;
SomeClass(){
this.str = "This is the string that never changes!";
}
public String getStr() {
return str;
}
@Override
public String toString() {
return "Class name: " + getClass() + " Value: " + getStr();
}
}
Some simple class with final String variable. So in the main class import java.lang.reflect.Field;
/**
* @author Dmitrijs Lobanovskis
* @since 03/03/2016.
*/
public class Main {
public static void main(String[] args) throws Exception{
SomeClass someClass = new SomeClass();
System.out.println(someClass);
Field field = someClass.getClass().getDeclaredField("str");
field.setAccessible(true);
field.set(someClass, "There you are");
System.out.println(someClass);
}
}
The output will be as follows:
Class name: class SomeClass Value: This is the string that never changes!
Class name: class SomeClass Value: There you are
Process finished with exit code 0
According to documentation https://docs.oracle.com/javase/tutorial/reflect/member/fieldValues.html