get Generic Parameter Types from Constructor

     
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import static java.lang.System.out;

import java.lang.reflect.Constructor;
import java.lang.reflect.Type;

public class ConstructorSift {
  public static void main(String... args) {
    try {
      Class<?> cArg = Class.forName(args[1]);

      Class<?> c = Class.forName(args[0]);
      Constructor[] allConstructors = c.getDeclaredConstructors();
      for (Constructor ctor : allConstructors) {
        Class<?>[] pType = ctor.getParameterTypes();
        for (int i = 0; i < pType.length; i++) {
          if (pType[i].equals(cArg)) {
            out.format("%s%n", ctor.toGenericString());

            Type[] gpType = ctor.getGenericParameterTypes();
            for (int j = 0; j < gpType.length; j++) {
              char ch = (pType[j].equals(cArg) ? '*' : ' ');
              out.format("%7c%s[%d]: %s%n", ch, "GenericParameterType", j,
                  gpType[j]);
            }
            break;
          }
        }
      }

      // production code should handle this exception more gracefully
    } catch (ClassNotFoundException x) {
      x.printStackTrace();
    }
  }
}

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get Generic Parameter Types from Constructor : Generic « Reflection « Java

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