构造器 (二)
intInitC(String s) {
System.out.println(s);
return 1;
}
}
class D {
D() {
System.out.println("D() constructor");
}
}
public class LoadClass extends B {
static int i = printInit("LoadClass.i initialized");
LoadClass() {
System.out.println("LoadClass() constructor");
}
public static void main(String[] args) {
// accessing static main causes loading (and initialization)
// of A, B, & LoadClass
System.out.println("hi");
// call constructors from loaded classes:
LoadClass lc = new LoadClass();
// call to static field loads & initializes C:
System.out.println(C.a);
// call to constructor loads D:
//D d = new D();
}
}
/**
* 请证明加载类的动作仅发生一次，证明该类的第一个实体
* 的创建或者对static成员的访问都有可能引起加载*/
class A {
static int j = printInit("A.j initialized");
static int printInit(String s) {
System.out.println(s);
return 1;
}
A() {
System.out.println("A() constructor");
}
}
class B extends A {
static int k = printInit("B.k initialized");
B() {
System.out.println("B() constructor");
}
}
class C {
static int n = printInitC("C.n initialized");
static A a = new A();
C() {
System.out.println("C() constructor");
}
static int printInitC(String s) {
System.out.println(s);
return 1;
}
}
class D {
D() {
System.out.println("D() constructor");
}
}
public class LoadClass extends B {
static int i = printInit("LoadClass.i initialized");
LoadClass() {
System.out.println("LoadClass() constructor");
}
public static void main(String[] args) {
// accessing static main causes loading (and initialization)
// of A, B, & LoadClass
System.out.println("hi");
// call constructors from loaded classes:
LoadClass lc = new LoadClass();
// call to static field loads & initializes C:
System.out.println(C.a);
// call to constructor loads D:
//D d = new D();
}
}