InternalCleaner.java

import java.lang.ref.Cleaner;

public class InternalCleaner {

  public static void main(String... args) throws Exception {
    while (true) {
      SensitiveData data = new SensitiveData();

      Thread.sleep(100);
      System.gc();
    }
  }

  static class SensitiveData {

    private final StateCleaner cleaner;

    public SensitiveData() {
      cleaner = new StateCleaner(this);
    }

    public void clear() {
      System.out.println("I'm getting cleared - yay!");
    }

  }

  static class StateCleaner {
    private static final Cleaner cleaner = Cleaner.create();

    static class State implements Runnable {

      private final SensitiveData data;

      State(SensitiveData data) {
        this.data = data;
      }

      public void run() {
        data.clear();
      }
    }

    private final Cleaner.Cleanable cleanable;

    public StateCleaner(final SensitiveData data) {
      this.cleanable = cleaner.register(this, new State(data));
    }

  }

}