英文:
Java generic type conversion like <String, String> to <Object, Object>
问题
从：<Object, Object> 到：<String, String>
或者
从：<String, String> 到：<Object, Object>
我在 ConcurrentKafkaListenerContainerFactory<Object, Object> 和 ConcurrentKafkaListenerContainerFactory<String, String> 之间有这种情况。
英文:
Is there a way in java to convert type
from : <Object, Object>
to : <String, String>
or
from : <String, String>
to : <Object, Object>
I have it between ConcurrentKafkaListenerContainerFactory<Object, Object> and ConcurrentKafkaListenerContainerFactory<String, String>
答案1
得分: 2
以下是翻译好的部分：
你必须使用中间的原始类型。这里有一个从 Object 到 String 转换的示例。反向转换看起来是相同的。
static ConcurrentKafkaListenerContainerFactory<Object, Object> stringFactoryToObjectFactory(
ConcurrentKafkaListenerContainerFactory<String, String> stringFactory) {
@SuppressWarnings("rawtypes")
ConcurrentKafkaListenerContainerFactory rawTypeFactory = stringFactory;
@SuppressWarnings("unchecked")
ConcurrentKafkaListenerContainerFactory<Object, Object> objectFactory = rawTypeFactory;
return objectFactory;
}
当然，这违反了类型安全性，如果这些工厂使用不同的类型，将在运行时引发 ClassCastException。
英文:
You have to use intermediate raw type. Here's an example for Object to String conversion. Reverse conversion will look identical.
static ConcurrentKafkaListenerContainerFactory<Object, Object> stringFactoryToObjectFactory(
ConcurrentKafkaListenerContainerFactory<String, String> stringFactory) {
@SuppressWarnings("rawtypes")
ConcurrentKafkaListenerContainerFactory rawTypeFactory = stringFactory;
@SuppressWarnings("unchecked")
ConcurrentKafkaListenerContainerFactory<Object, Object> objectFactory = rawTypeFactory;
return objectFactory;
}
Of course it violates type safety and ClassCastException will occur at runtime, if those factories will use different types.
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