泛型问题# Java - 爪哇娇娃
e*7
1 楼
我已经听了kite runner, harry potter 1-7, lord of the ring 1-3, 哪里有什么其
他的英文小说的audio book？
他的英文小说的audio book？
s*e
3 楼
鬼灵报告 第2部 周氏兄弟 第86章 哀煞离身
“孙大鹏在下边么…？”魏笑彤从上边喊道。
“暂时没看见！下边好像没什么危险，你下来吧！”钟鬼灵用手电照了照岩缝深处
，似乎没什么动静。
“万一他没到这底下来，咱们把他弄丢了，回去怎么和茅山派那个张老道交代？”
没多会，魏笑彤也下到了裂缝底下。
“他出不了事！”钟鬼灵斩钉截铁道，“一来刚才那东西绝非什么厉害玩艺，二来
我猜想那很有可能是贺掌石布阵的一部分，冲孙大鹏身子的东西很可能只是引路，应该
不会伤他性命…”
道教曾有过这样的传说野史，就是世间存在一种叫“垩垆”的地方，“垩”的意思
是白色土，而“垆” 则是黑色土的意思，白为阳，黑为阴，“垩垆”拼在一起，便代
表阴阳交替的地方，相传这种地方是得道成仙者踏步仙境的必经之路，更有甚者，甚至
认为“垩垆” 就是仙界与人界的重叠处，是修道成仙后继续修行的第一站，也就是说
只有成了仙才有资格观光，凡夫俗子是没有资格进入的，如果普通人误打误撞撞上了，
则应该严格保守秘密，否则就是泄露天机。
道门野史相传，当年鬼谷子就是误打误撞发现了一处“垩垆”，便以凡人之身留在
那里修行，后来终于得道成仙，之
“孙大鹏在下边么…？”魏笑彤从上边喊道。
“暂时没看见！下边好像没什么危险，你下来吧！”钟鬼灵用手电照了照岩缝深处
，似乎没什么动静。
“万一他没到这底下来，咱们把他弄丢了，回去怎么和茅山派那个张老道交代？”
没多会，魏笑彤也下到了裂缝底下。
“他出不了事！”钟鬼灵斩钉截铁道，“一来刚才那东西绝非什么厉害玩艺，二来
我猜想那很有可能是贺掌石布阵的一部分，冲孙大鹏身子的东西很可能只是引路，应该
不会伤他性命…”
道教曾有过这样的传说野史，就是世间存在一种叫“垩垆”的地方，“垩”的意思
是白色土，而“垆” 则是黑色土的意思，白为阳，黑为阴，“垩垆”拼在一起，便代
表阴阳交替的地方，相传这种地方是得道成仙者踏步仙境的必经之路，更有甚者，甚至
认为“垩垆” 就是仙界与人界的重叠处，是修道成仙后继续修行的第一站，也就是说
只有成了仙才有资格观光，凡夫俗子是没有资格进入的，如果普通人误打误撞撞上了，
则应该严格保守秘密，否则就是泄露天机。
道门野史相传，当年鬼谷子就是误打误撞发现了一处“垩垆”，便以凡人之身留在
那里修行，后来终于得道成仙，之
A*e
5 楼
amazon.com
【在 e*******7 的大作中提到】
: 我已经听了kite runner, harry potter 1-7, lord of the ring 1-3, 哪里有什么其
: 他的英文小说的audio book？
【在 e*******7 的大作中提到】
: 我已经听了kite runner, harry potter 1-7, lord of the ring 1-3, 哪里有什么其
: 他的英文小说的audio book？
F*k
6 楼
这能干嘛
s*e
7 楼
why don't you just use the A's compareTo() method? it seems to be your
intention to compare them as A, no matter whether subtype they are.
or if you do care their type, you might override the compareTo() method like:
if (!(a instanceof B)) throws new SomeException();
return super.compareTo(a);
but i do suspect it's not what you want it to do.
【在 A**o 的大作中提到】
: if A implements Comparable
: and B extends A
: then B can't implements Comparable
: so, what should i do to make it work?
: currently, i have to override in B using:
: compareTo(A a) then do type checking and all the same shit. :(
intention to compare them as A, no matter whether subtype they are.
or if you do care their type, you might override the compareTo() method like:
if (!(a instanceof B)) throws new SomeException();
return super.compareTo(a);
but i do suspect it's not what you want it to do.
【在 A**o 的大作中提到】
: if A implements Comparable
: and B extends A
: then B can't implements Comparable
: so, what should i do to make it work?
: currently, i have to override in B using:
: compareTo(A a) then do type checking and all the same shit. :(
e*7
8 楼
faint. 我要不花钱的..
g*e
9 楼
免费印一张16x20的大幅照片。
【在 F*********k 的大作中提到】
: 这能干嘛
【在 F*********k 的大作中提到】
: 这能干嘛
A*o
10 楼
It was what i want. And I'm doing exactly that.
type checking, casting or throw exception, compare instance of B...
isn't that back to the days before generic?
what's the point of generic, then?
like:
【在 s***e 的大作中提到】
: why don't you just use the A's compareTo() method? it seems to be your
: intention to compare them as A, no matter whether subtype they are.
: or if you do care their type, you might override the compareTo() method like:
: if (!(a instanceof B)) throws new SomeException();
: return super.compareTo(a);
: but i do suspect it's not what you want it to do.
type checking, casting or throw exception, compare instance of B...
isn't that back to the days before generic?
what's the point of generic, then?
like:
【在 s***e 的大作中提到】
: why don't you just use the A's compareTo() method? it seems to be your
: intention to compare them as A, no matter whether subtype they are.
: or if you do care their type, you might override the compareTo() method like:
: if (!(a instanceof B)) throws new SomeException();
: return super.compareTo(a);
: but i do suspect it's not what you want it to do.
m*g
11 楼
verycd有一些
【在 e*******7 的大作中提到】
: faint. 我要不花钱的..
【在 e*******7 的大作中提到】
: faint. 我要不花钱的..
b*y
12 楼
谢谢
这个真好，不过不知道有人试过么？coupon可用么？
这个真好，不过不知道有人试过么？coupon可用么？
s*e
13 楼
generic is making methods more specific for a specific type. I think your
problem is not about generic. the problem comes out from the fact that B
extends A, no matter you use generic or not.
If B is not a subclass of A, then both A implements Comparable and B
implements Comparable make sense.
But if you make B a subclass of A, then B must fulfill the contract that A
provides, which is the method: int compareTo(A). I think you do want the
compareTo() method to be at the level of A, and not
【在 A**o 的大作中提到】
: It was what i want. And I'm doing exactly that.
: type checking, casting or throw exception, compare instance of B...
: isn't that back to the days before generic?
: what's the point of generic, then?
:
: like:
problem is not about generic. the problem comes out from the fact that B
extends A, no matter you use generic or not.
If B is not a subclass of A, then both A implements Comparable and B
implements Comparable make sense.
But if you make B a subclass of A, then B must fulfill the contract that A
provides, which is the method: int compareTo(A). I think you do want the
compareTo() method to be at the level of A, and not
【在 A**o 的大作中提到】
: It was what i want. And I'm doing exactly that.
: type checking, casting or throw exception, compare instance of B...
: isn't that back to the days before generic?
: what's the point of generic, then?
:
: like:
v*u
14 楼
verycd 有无数
其实只要能有名字的, 在书店卖的, 那么驴子上就应该有
但是什么值得听就需要花时间想想了.
【在 m*********g 的大作中提到】
: verycd有一些
其实只要能有名字的, 在书店卖的, 那么驴子上就应该有
但是什么值得听就需要花时间想想了.
【在 m*********g 的大作中提到】
: verycd有一些
s*e
15 楼
or you can consider Comparator anyway:
class A {
class MyComparator implements Comparator {
@Override
public int compare(A o1, A o2) {
// ...
return 0;
}
}
}
【在 A**o 的大作中提到】
: It was what i want. And I'm doing exactly that.
: type checking, casting or throw exception, compare instance of B...
: isn't that back to the days before generic?
: what's the point of generic, then?
:
: like:
class A {
class MyComparator implements Comparator {
@Override
public int compare(A o1, A o2) {
// ...
return 0;
}
}
}
【在 A**o 的大作中提到】
: It was what i want. And I'm doing exactly that.
: type checking, casting or throw exception, compare instance of B...
: isn't that back to the days before generic?
: what's the point of generic, then?
:
: like:
e*o
16 楼
都是很经典的， 不过听的时候有点费劲。 偶开车的时候听过NANNY DIARY, DEVIL
WEARS PRADA..
【在 e*******7 的大作中提到】
: 我已经听了kite runner, harry potter 1-7, lord of the ring 1-3, 哪里有什么其
: 他的英文小说的audio book？
WEARS PRADA..
【在 e*******7 的大作中提到】
: 我已经听了kite runner, harry potter 1-7, lord of the ring 1-3, 哪里有什么其
: 他的英文小说的audio book？
F*n
17 楼
Just use two variable to reference the same instance of B:
B b = new B()...;
A a = b;
Then use b to invoke B specific methods and a to compare.
【在 A**o 的大作中提到】
: if A implements Comparable
: and B extends A
: then B can't implements Comparable
: so, what should i do to make it work?
: currently, i have to override in B using:
: compareTo(A a) then do type checking and all the same shit. :(
B b = new B()...;
A a = b;
Then use b to invoke B specific methods and a to compare.
【在 A**o 的大作中提到】
: if A implements Comparable
: and B extends A
: then B can't implements Comparable
: so, what should i do to make it work?
: currently, i have to override in B using:
: compareTo(A a) then do type checking and all the same shit. :(
L*t
18 楼
我刚听了Bafallo Bill, 很好听.
F*n
19 楼
If A is supposed to be extended, it should be declared like
public class A implements Comparable {
public int compareTo(T t) {
...
}
}
Since it is very likely A will be compared with sub-classes of A.
【在 A**o 的大作中提到】
: It was what i want. And I'm doing exactly that.
: type checking, casting or throw exception, compare instance of B...
: isn't that back to the days before generic?
: what's the point of generic, then?
:
: like:
public class A
public int compareTo(T t) {
...
}
}
Since it is very likely A will be compared with sub-classes of A.
【在 A**o 的大作中提到】
: It was what i want. And I'm doing exactly that.
: type checking, casting or throw exception, compare instance of B...
: isn't that back to the days before generic?
: what's the point of generic, then?
:
: like:
S*9
20 楼
图书馆的AUDIO BOOK可以下载到电脑或爱疯
m*t
21 楼
B can override compareTo but still fulfill the contract,
as long as B.compareTo(A) works. That's actually the
essence of the problem.
The T in Comparable
A implements Comparable
says is that A is comparable to T, and _only_ comparable to T.
So if A already implements Comaprable, so would B from the
inheritance, and it would violate the contract for B to
(re)implement Comparable, because that would mean that B is
no longer comparable to A.
【在 s***e 的大作中提到】
: generic is making methods more specific for a specific type. I think your
: problem is not about generic. the problem comes out from the fact that B
: extends A, no matter you use generic or not.
: If B is not a subclass of A, then both A implements Comparable and B
: implements Comparable make sense.
: But if you make B a subclass of A, then B must fulfill the contract that A
: provides, which is the method: int compareTo(A). I think you do want the
: compareTo() method to be at the level of A, and not
S*9
22 楼
旱成这样 what a shame
s*e
23 楼
well, what you said is alright, which is showed in the compile error.
but I think what LZ needs is just for A to use Comparable, and for B to
use Comparable. it happens to be not possible if B extends A. so
Comparator is a way to get around.
【在 m******t 的大作中提到】
:
: B can override compareTo but still fulfill the contract,
: as long as B.compareTo(A) works. That's actually the
: essence of the problem.
: The T in Comparable doesn't really have to be A. All
: A implements Comparable
: says is that A is comparable to T, and _only_ comparable to T.
: So if A already implements Comaprable, so would B from the
: inheritance, and it would violate the contract for B to
: (re)implement Comparable, because that would mean that B is
but I think what LZ needs is just for A to use Comparable, and for B to
use Comparable. it happens to be not possible if B extends A. so
Comparator is a way to get around.
【在 m******t 的大作中提到】
:
: B can override compareTo but still fulfill the contract,
: as long as B.compareTo(A) works. That's actually the
: essence of the problem.
: The T in Comparable
: A implements Comparable
: says is that A is comparable to T, and _only_ comparable to T.
: So if A already implements Comaprable, so would B from the
: inheritance, and it would violate the contract for B to
: (re)implement Comparable, because that would mean that B is
e*o
24 楼
讲什么故事的？
【在 L********t 的大作中提到】
: 我刚听了Bafallo Bill, 很好听.
【在 L********t 的大作中提到】
: 我刚听了Bafallo Bill, 很好听.
e*o
25 楼
讲什么故事的？
【在 L********t 的大作中提到】
: 我刚听了Bafallo Bill, 很好听.
【在 L********t 的大作中提到】
: 我刚听了Bafallo Bill, 很好听.
s*e
26 楼
我是去社区图书馆借。免费。
BRIDGET JONES’ DIARY 很可乐，适合上下班的路上听。
BRIDGET JONES’ DIARY 很可乐，适合上下班的路上听。
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