public class ShowTest{

public static void main(String[] args) {

Singleton si = new Singleton();

si.printMessage();



}

}

class Singleton {

private static Singleton instance = new Singleton();

public static Singleton getInstance(){

return instance;

}

public String printMessage(){

return "我代表一个功能，已完成！";

}

private Singleton(){};

}

这个代码为啥是错的