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1 | static Map<Class, Constructor> nuEmptyObject_cache = newDangerousWeakHashMap(); |
2 | |
3 | static <A> A nuEmptyObject(Class<A> c) ctex {
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4 | Constructor ctr; |
5 | |
6 | synchronized(nuEmptyObject_cache) {
|
7 | ctr = nuEmptyObject_cache.get(c); |
8 | if (ctr == null) {
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9 | nuEmptyObject_cache.put(c, ctr = nuEmptyObject_findConstructor(c)); |
10 | makeAccessible(ctr); |
11 | } |
12 | } |
13 | |
14 | try {
|
15 | ret (A) ctr.newInstance(); |
16 | } catch (InstantiationException e) {
|
17 | if (empty(e.getMessage())) |
18 | if ((c.getModifiers() & Modifier.ABSTRACT) != 0) |
19 | fail("Can't instantiate abstract class " + className(c), e);
|
20 | else |
21 | fail("Can't instantiate " + className(c), e);
|
22 | else throw rethrow(e); |
23 | } |
24 | } |
25 | |
26 | static Constructor nuEmptyObject_findConstructor(Class c) {
|
27 | for (Constructor m : getDeclaredConstructors_cached(c)) |
28 | if (m.getParameterTypes().length == 0) |
29 | ret m; |
30 | fail("No default constructor declared in " + c.getName());
|
31 | } |
Began life as a copy of #1001136
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| Snippet ID: | #1005599 |
| Snippet name: | nuEmptyObject - fast way to make an empty instance of a class (using default constructor) |
| Eternal ID of this version: | #1005599/10 |
| Text MD5: | 5856fab1a26b8fc0e34ac3ca926c8425 |
| Transpilation MD5: | 01b54238145bb60fe4839aa8030664e8 |
| Author: | stefan |
| Category: | javax |
| Type: | JavaX fragment (include) |
| Public (visible to everyone): | Yes |
| Archived (hidden from active list): | No |
| Created/modified: | 2022-03-29 19:42:53 |
| Source code size: | 962 bytes / 31 lines |
| Pitched / IR pitched: | No / No |
| Views / Downloads: | 647 / 793 |
| Version history: | 9 change(s) |
| Referenced in: | [show references] |