ModifyingPrivateFields.java

package thinkinginjava.typeinfo;

import java.lang.reflect.*;

class WithPrivateFinalField {
	private int i = 1;
	private final String s = "I'm totally safe";
	private String s2 = "Am I safe?";

	public String toString() {
		return "i = " + i + ", " + s + ", " + s2;
	}
}

public class ModifyingPrivateFields {
	public static void main(String[] args) throws Exception {
		WithPrivateFinalField pf = new WithPrivateFinalField();
		System.out.println(pf);
		
		Field f = pf.getClass().getDeclaredField("i");
		f.setAccessible(true);
		System.out.println("f.getInt(pf): " + f.getInt(pf));
		f.setInt(pf, 47);
		System.out.println(pf);
		
		f = pf.getClass().getDeclaredField("s");
		f.setAccessible(true);
		System.out.println("f.get(pf): " + f.get(pf));
		f.set(pf, "No, you're not!");
		System.out.println(pf);
		
		f = pf.getClass().getDeclaredField("s2");
		f.setAccessible(true);
		System.out.println("f.get(pf): " + f.get(pf));
		f.set(pf, "No, you're not!");
		System.out.println(pf);
	}
}