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Java初始化顺序
1、在类的内部,变量的定义的先后顺序决定了初始化顺序,即使变量定义散布于方法定义间,他们仍旧会在任何方法(包括构造器)被调用之前得到初始化
2、静态数据的初始化
class Bowl{ Bowl(int marker){ print("Bowl("+marker+")"); } void f1(int marker){ print("f1("+marker+")"); } class Table{ static Bowl bowl1=new Bowl(1); Table(){ print("Table()"); bowl2.f1(1); } void f2(int marker){ print("f2("+marker+")"); } static Bowl bowl2=new Bowl(2); } } class Cupboard{ Bowl bowl3=new Bowl(3); static Bowl bowl4=new Bowl(4); Cupboard(){ print("Cupboard()"); bowl4.f1(2); } void f3(int marker){ print("f3("+marker+")"); } static Bowl bowl5=new Bowl(5); } public class StaticInitialization{ public static void main(String args[]){ print("Creating new Cupboard() in main"); new Cupboard(); print("Creating new Cupboard() in main"); new Cupboard(); table.f2(1); cupboard.f3(1); } static Table table=new Table(); static Cupboard cupboard=new Cupboard(); }
output:
Bowl(1)
Bowl(2)
Table()
f1(1)
Bowl(4)
Bowl(5)
Bowl(3)
Cupboard()
f1(2)
Creating new Cupboard() in main
Bowl(3)
Cupboard()
f1(2)
Creating new Cupboard() in main
Bowl(3)
Cupboard()
f1(2)
f2(1)
f3(1)
3、显式的静态初始化
class Cup{ Cup(int marker){print("Cup("+marker+")");} void f(int marker){print("f("+marker+")");} } class Cups{ static Cup cup1; static Cup cup2; static { cup1=new Cup(1); cup2=new Cup(2); } Cups(){ print("Cups()"); } public class ExlicitStatic{ public static void main(String args[]){ print("Inside main()"); Cups.cup1.f(99); //(1) } //static Cups cup1=new Cup(); //(2) //static Cups cup2=new Cup(); //(2) } }
output:
Cup(1)
Cup(2)
f(99)
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