Nested Classes in Java (Rules)
1. The inner class(non-static nested) has access to all of the outer class's members, including those marked private , directly(without inst.)
2. To instantiate an inner class, you must have a reference to an instance of the outer class.
syntax :
Instantiating a non-static nested class requires using both the outer inst and nested class names as follows:
BigOuter.Nested n = new BigOuter().new Nested();
3. Such Inner classes cant have static members.(From JDK 1.8 onwards can have --static final members)
About method-local inner classes
1.A method-local inner class is defined within a method of the enclosing class.
2.For the inner class to be used, you must instantiate it, and that instantiation must happen within the same method, but after the class definition code.
3. A method-local inner class cannot use variables declared within the method
(including parameters) unless those variables are marked final.
static nested classes
1.A static nested class is not an inner class, it's a top-level nested class.
2. You don't need an instance of the
outer class to instantiate a static nested class.
4.It cannot access non-static members of the outer class directly BUT can access static members of the outer class.
5. It can contain both static & non-static members.
6. JVM will not load any class's static init block -- until u actually refer to something from that class.
(Lazy loading) This is true for static nested classes too.
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