//: generics/InstantiateGenericType.java
import static net.mindview.util.Print.*;
class ClassAsFactory<T> {
T x;
public ClassAsFactory(Class<T> kind) {
try {
x = kind.newInstance();
} catch(Exception e) {
throw new RuntimeException(e);
}
}
}
class Employee {}
public class InstantiateGenericType {
public static void main(String[] args) {
ClassAsFactory<Employee> fe =
new ClassAsFactory<Employee>(Employee.class);
print("ClassAsFactory<Employee> succeeded");
try {
ClassAsFactory<Integer> fi =
new ClassAsFactory<Integer>(Integer.class);
} catch(Exception e) {
print("ClassAsFactory<Integer> failed");
}
}
} /* Output:
ClassAsFactory<Employee> succeeded
ClassAsFactory<Integer> failed
*///:~
因为Integer没有默认构造器 所以会编译失败