了解类加载机制

知道下面的程序输出的内容么?

public class Singleton {
  private static Singleton singleton = new Singleton();
  public static int counter1;
  public static int counter2 = 0;
  private Singleton() {
      counter1++;
      counter2++;
  }
  public static Singleton getSingleton() {
      return singleton;
  }
 }

  public class TestSingleton {
    public static void main(String args[]){
        Singleton singleton = Singleton.getSingleton();
        System.out.println("counter1="+singleton.counter1);
        System.out.println("counter2="+singleton.counter2);
    }
}