带有静态初始化程序的java嵌套类

Question

正在读一本名为Emergent Design的书,关于单身人士的话题......

public class MyApp {
 private class SingletonHolder {
  public Object singleton; 
  static {
   singleton = new Object(); 
  }
 }
}

然后eclipse一直抱怨静态{}

正在阅读Java,类应该能够拥有多个静态初始化器.那么我怎样才能完成上述工作呢？

---

/tmp/jc_4873/MyApp.java:5: non-static variable singleton cannot be referenced from a static context
   singleton = new Object(); 
   ^
/tmp/jc_4873/MyApp.java:4: inner classes cannot have static declarations
  static {
  ^
2 errors

---

public class MyApp {
 private class SingletonHolder {
  public static Object singleton; 
  static {
   singleton = new Object(); 
  }
 }
}

/tmp/jc_8488/MyApp.java:3: inner classes cannot have static declarations
  public static Object singleton; 
                       ^
/tmp/jc_8488/MyApp.java:4: inner classes cannot have static declarations
  static {
  ^
2 errors

---

public class MyApp {
 private static class SingletonHolder {
  public static Object singleton; 
  static {
   singleton = new Object(); 
  }
 }
}

Answer 1

对于要在静态上下文中合法引用的字段,该字段必须是上下文的本地字段,或者在类中声明为静态字段.如果要引用singleton,则需要声明它static.