[英]Java generics ? extends Clazz
I'm using spring, hibernate and junit to setup a test class for some of my models. 我正在使用spring,hibernate和junit为我的某些模型设置测试类。
All of my models extend BaseModel 我所有的模型都扩展了BaseModel
I have the following function in my testing class: 我的测试课中有以下功能:
void printValidation(Set<ConstraintViolation<? extends BaseModel>> v){
Iterator<ConstraintViolation<? extends BaseModel>> it = v.iterator();
while (it.hasNext()) {
ConstraintViolation<? extends BaseModel> violation = it.next();
l.info("Validation error {}", violation);
}
}
I use it like so inside a test case: 我在测试用例中这样使用它:
eModel = new Entry(); //This class extends BaseModel
Set<ConstraintViolation<? extends BaseModel>> v = validator.validate(eModel);
assertTrue("There should be validation errors...", v.size() > 0);
printValidation(v);
However, I get the following message in Eclipse, and it does not seem to work: Type mismatch: cannot convert from Set<ConstraintViolation<Entry>>
to Set<ConstraintViolation<? extends BaseModel>>
但是,我在Eclipse中收到以下消息,并且似乎不起作用:类型不匹配:无法从
Set<ConstraintViolation<Entry>>
转换为Set<ConstraintViolation<? extends BaseModel>>
Set<ConstraintViolation<? extends BaseModel>>
I have a bunch of other tests, and if I make the function take <Entry>
instead of <? extends BaseEntry>
我还有很多其他测试,如果我使函数采用
<Entry>
而不是<? extends BaseEntry>
<? extends BaseEntry>
it works. <? extends BaseEntry>
起作用。 I have a number of models I'm testing like this, and it is sort of the whole point of generics to not have to duplicate this. 我有很多这样的模型正在测试,而通用类的全部要点就是不必复制它。
What am I missing here, I guess it has something to do with either what validator.validate is returning or something? 我在这里想念的是什么,我想这可能与validator.validate返回什么有关?
** Edited to fix inline code formatting ** **编辑以修复内联代码格式**
@geoand - Almost, here is the working code: @geoand-差不多,这是工作代码:
<T extends BaseModel> void printValidation(Set<ConstraintViolation<T>> v){
Iterator<ConstraintViolation<T>> it = v.iterator();
while (it.hasNext()) {
ConstraintViolation<T> violation = it.next();
l.info("Validation error {}", violation);
}
}
And the function that does the test: 和做测试的功能:
@Test
public void testEntry() {
Set<ConstraintViolation<Entry>> v = validator.validate(eModel);
assertTrue("There should be validation errors...", v.size() > 0);
printValidation(v);
尝试void <T extends BaseModel> printValidation(Set<ConstraintViolation<T>> v)
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