final对基本类型,限定常量。
final对对象的引用,不可引用其他对象。
final的字段,必须在定义时或者构造器内完成初始化。构造内才完成初始化的Blank Final(空白final)。
class Poppet{private int i ;public Poppet(int ii){i = ii;}}class BlankFinal{private int i = 100;private final int j ;private final Poppet p;//BlankFinal field must be init in constructorpublic BlankFinal(){j = 10;p = new Poppet(10);}public BlankFinal(int x){j = x;p = new Poppet(x);}}