2007-01-04 | java的初始化(2)【转载】
上一篇 / 下一篇 2007-04-27 17:58:48 / 个人分类:编程基础
1.初始化的顺序
对类而言,初始化的顺序是由变量在类的定义里面的顺序决定的,变量的定义可能会分散在类定义的各个地方,并且与方法的定义相互交错,但是变量的初始化会先于任何方法,甚至是构造函数的调用。
class Tag {51Testing软件测试网0q"~3_(qzq5d\c
Tag(int marker) {51Testing软件测试网2I2XJ3uH5v;n)}0@
System.out.println("Tag(" + marker + ")");51Testing软件测试网.Zs)@ s0``
}51Testing软件测试网~:m-\9N+E"GGp&Es/Q3SQ j
}51Testing软件测试网0Qy#X|xm:_
class Card {
-E*l:kWU k0 Tag t1 = new Tag(1); // Before constructor51Testing软件测试网N s]|9x
Card() {51Testing软件测试网b TK.u u6`?!f4S`P
// Indicate we're in the constructor:
} ODf^0 System.out.println("Card()");51Testing软件测试网)U[vH+D
t3 = new Tag(33); // Reinitialize t3
`(bdV!?)a _*|5xE3v u0 }
?FK_W C_p0 Tag t2 = new Tag(2); // After constructor
0{Wkk:L0 void f() {
$SO(dzgQ.?!b0 System.out.println("f()");51Testing软件测试网Q z7ym+V*CM
}51Testing软件测试网 C|!q.ld8wa
Tag t3 = new Tag(3); // At end
j7x zvP3w!xj|0}
9g*fpKP$Aa ]0public class Flower {51Testing软件测试网m?kT4_e~u,D%Y
public static void main(String[] args) {
]^)E|%JW0 Card t = new Card();
CiE7`u [[Po0 t.f(); // Shows that construction is done51Testing软件测试网E&R9VqJik;G
}51Testing软件测试网)i ~+wo6W(M,T:w
}
Tag(int marker) {51Testing软件测试网2I2XJ3uH5v;n)}0@
System.out.println("Tag(" + marker + ")");51Testing软件测试网.Zs)@ s0``
}51Testing软件测试网~:m-\9N+E"GGp&Es/Q3SQ j
}51Testing软件测试网0Qy#X|xm:_
class Card {
-E*l:kWU k0 Tag t1 = new Tag(1); // Before constructor51Testing软件测试网N s]|9x
Card() {51Testing软件测试网b TK.u u6`?!f4S`P
// Indicate we're in the constructor:
} ODf^0 System.out.println("Card()");51Testing软件测试网)U[vH+D
t3 = new Tag(33); // Reinitialize t3
`(bdV!?)a _*|5xE3v u0 }
?FK_W C_p0 Tag t2 = new Tag(2); // After constructor
0{Wkk:L0 void f() {
$SO(dzgQ.?!b0 System.out.println("f()");51Testing软件测试网Q z7ym+V*CM
}51Testing软件测试网 C|!q.ld8wa
Tag t3 = new Tag(3); // At end
j7x zvP3w!xj|0}
9g*fpKP$Aa ]0public class Flower {51Testing软件测试网m?kT4_e~u,D%Y
public static void main(String[] args) {
]^)E|%JW0 Card t = new Card();
CiE7`u [[Po0 t.f(); // Shows that construction is done51Testing软件测试网E&R9VqJik;G
}51Testing软件测试网)i ~+wo6W(M,T:w
}
输出结果如下:
Tag(1)
Tag(2)
Tag(3)
Card()
Tag(33)
f()
2.静态数据的初始化
无论创建多少对象,static数据只能有一份。它的初始化不是在定义的时候进行的。
class Bowl {51Testing软件测试网+KZ e v2C C%J
Bowl(int marker) {
ZeY0B,S,U mB0 System.out.println("Bowl(" + marker + ")");51Testing软件测试网8k2QE i?
}
f4t0a#_7B;fd0 void f(int marker) {
Ou.R~E)b.x0 System.out.println("f(" + marker + ")");
E W3j/Yd B:EeS0 }
*n-d4\Bn5v2I+x;B0}
Ao.k-h'w;H*E5w[0class Table {51Testing软件测试网Q.} h3@B!e k7|
static Bowl b1 = new Bowl(1);
'ld yX\4\p-`7Wn S5k0 Table() {51Testing软件测试网e V7YYj&j;kmS+V
System.out.println("Table()");
Is)^Uw0 b2.f(1);51Testing软件测试网 C,N&~^ @8F^6p
}
UOe)Qx0 void f2(int marker) {51Testing软件测试网3o(?f~)ysw$G/yg
System.out.println("f2(" + marker + ")");51Testing软件测试网Q;hDR%N
}
jIu0A9~;oT0 static Bowl b2 = new Bowl(2);
MSfh YWJ0}
nrDg)Z^0class Cupboard {
"Y.[&C|)vh.W.p"|6^0 Bowl b3 = new Bowl(3);51Testing软件测试网_0{f WnO*o4w$Ab
static Bowl b4 = new Bowl(4);51Testing软件测试网t0k1Mpe1Bj
Cupboard() {51Testing软件测试网k"i5kw%`D
System.out.println("Cupboard()");
/Pz&}%{&fnqh0 b4.f(2);51Testing软件测试网 G] N-~G@"IRi2KN
}51Testing软件测试网 WL&F3sKV0_
void f3(int marker) {
Bowl(int marker) {
ZeY0B,S,U mB0 System.out.println("Bowl(" + marker + ")");51Testing软件测试网8k2QE i?
}
f4t0a#_7B;fd0 void f(int marker) {
Ou.R~E)b.x0 System.out.println("f(" + marker + ")");
E W3j/Yd B:EeS0 }
*n-d4\Bn5v2I+x;B0}
Ao.k-h'w;H*E5w[0class Table {51Testing软件测试网Q.} h3@B!e k7|
static Bowl b1 = new Bowl(1);
'ld yX\4\p-`7Wn S5k0 Table() {51Testing软件测试网e V7YYj&j;kmS+V
System.out.println("Table()");
Is)^Uw0 b2.f(1);51Testing软件测试网 C,N&~^ @8F^6p
}
UOe)Qx0 void f2(int marker) {51Testing软件测试网3o(?f~)ysw$G/yg
System.out.println("f2(" + marker + ")");51Testing软件测试网Q;hDR%N
}
jIu0A9~;oT0 static Bowl b2 = new Bowl(2);
MSfh YWJ0}
nrDg)Z^0class Cupboard {
"Y.[&C|)vh.W.p"|6^0 Bowl b3 = new Bowl(3);51Testing软件测试网_0{f WnO*o4w$Ab
static Bowl b4 = new Bowl(4);51Testing软件测试网t0k1Mpe1Bj
Cupboard() {51Testing软件测试网k"i5kw%`D
System.out.println("Cupboard()");
/Pz&}%{&fnqh0 b4.f(2);51Testing软件测试网 G] N-~G@"IRi2KN
}51Testing软件测试网 WL&F3sKV0_
void f3(int marker) {
System.out.println("f3(" + marker + ")");51Testing软件测试网r(E4rQU
}51Testing软件测试网[M3vcfg%VD*P3g
static Bowl b5 = new Bowl(5);
.VjYE;kQ0}
~rv.W.I }%ut ?Mo6a%c%e0public class E1 {
%gTT?*j-B0 public static void main(String[] args) {
/ow {W*j2]t0k@0 System.out.println("Creating new Cupboard() in main");51Testing软件测试网6ys)i0ac1NsC
new Cupboard();
~Yh\j0 System.out.println("Creating new Cupboard() in main");51Testing软件测试网;\{yq-_d
new Cupboard();
}51Testing软件测试网[M3vcfg%VD*P3g
static Bowl b5 = new Bowl(5);
.VjYE;kQ0}
~rv.W.I }%ut ?Mo6a%c%e0public class E1 {
%gTT?*j-B0 public static void main(String[] args) {
/ow {W*j2]t0k@0 System.out.println("Creating new Cupboard() in main");51Testing软件测试网6ys)i0ac1NsC
new Cupboard();
~Yh\j0 System.out.println("Creating new Cupboard() in main");51Testing软件测试网;\{yq-_d
new Cupboard();
Table t2 = new Table();