在Java中编写单例的不同方法

在java中编写单例的经典之处如下：

The classic of writing a singleton in java is like this:

public class SingletonObject
{
    private SingletonObject()
    {
    }

    public static SingletonObject getSingletonObject()
    {
      if (ref == null)
          // it's ok, we can call this constructor
          ref = new SingletonObject();
      return ref;
    }

    private static SingletonObject ref;
}

如果我们需要在多线程情况下运行它们，我们可以添加synchronized关键字。

and we can add synchronized keyword if we need it to run in multithreaded cases.

但我更喜欢把它写成：

public class SingletonObject
{
    private SingletonObject()
    {
        // no code req'd
    }

    public static SingletonObject getSingletonObject()
    {
      return ref;
    }

    private static SingletonObject ref = new SingletonObject();
}

我觉得更简洁，但奇怪的是我没有看到任何样本以这种方式编写的代码，如果我以这种方式编写代码会有什么不良影响吗？

which I think is more concise, but strangely I didn't see any sample code written in this way, is there any bad effects if I wrote my code in this way?