Get Parameter type from Constructor using reflection - Java Reflection

Java examples for Reflection:Constructor

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Description

Get Parameter type from Constructor using reflection

Demo Code

import java.lang.reflect.Constructor;
import java.lang.reflect.Type;
import static java.lang.System.out;

public class ConstructorSift {
    public static void main(String... args) {
        try {//  w w  w .  j av  a  2 s.  c  o m
            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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