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how to do this?

how to do this?# Java - 爪哇娇娃

b*d2009-01-14 08:01

1 楼

i have a generic class
class Dummy {
public Dummy() {
}
private T dummy;
}
how to instantiate the dummy field in ctor? how to achieve "new T()" like in c+
+?

t*e2009-01-14 08:01

2 楼

You cannot instantiate it. Generic typed variables are fed through method input
parameters.

b*d2009-01-14 08:01

3 楼

ok then can i instantiate dummy in a non-ctor method?

input

【在 t*******e 的大作中提到】

: You cannot instantiate it. Generic typed variables are fed through method input
: parameters.

t*e2009-01-14 08:01

4 楼

What's you intent? Describe you use case.

F*n2009-01-14 08:01

5 楼

There is no way. Unlike C++, Java Generics is a compile-time thing. You
cannot dynamically create it during time.

in c+

【在 b*d 的大作中提到】

: i have a generic class
: class Dummy {
: public Dummy() {
: }
: private T dummy;
: }
: how to instantiate the dummy field in ctor? how to achieve "new T()" like in c+
: +?

s*k2009-01-14 08:01

6 楼

I'm a little confused. Isn't C++ template a "compile-time thing" too?

【在 F****n 的大作中提到】

: There is no way. Unlike C++, Java Generics is a compile-time thing. You
: cannot dynamically create it during time.
:
: in c+

F*n2009-01-14 08:01

7 楼

Java template variable declaration, (not type parameters in class definition
), does NOT have any impact on compiled binary code. Search for type erasure.

【在 s*****k 的大作中提到】

: I'm a little confused. Isn't C++ template a "compile-time thing" too?