The getParameterCount() method of java.lang.reflect.Constructor class is used to return the number of parameters present on this constructor object. Every constructor contains a number of parameters starting from zero to many. This method is helpful to get those numbers of parameters.
Syntax:
public int getParameterCount()
Parameters: This method accepts nothing.
Return: This method returns the number of formal parameters for the executable this object represents.
Below programs illustrate getParameterCount() method:
Program 1:
// Java program to illustrate getParameterCount() method  import java.lang.reflect.Constructor;  public class GFG {      public static void main(String[] args)    {        // create a class object        Class classObj = String.class;          // get Constructor object        // array from class object        Constructor[] cons = classObj.getConstructors();          // get count of parameter        int params = cons[0].getParameterCount();          // print parameter count        System.out.println("No of Parameters: " + params);    }} |
Output:
No of Parameters: 3
Program 2:
// Java program to illustrate getParameterCount() method  import java.lang.reflect.Constructor;import java.util.ArrayList;  public class GFG {      public static void main(String[] args)    {        // create a class object        Class classObj = ArrayList.class;          // get Constructor object        // array from class object        Constructor[] cons = classObj.getConstructors();          for (int i = 0; i < cons.length; i++) {            // get count of parameter            int params = cons[i].getParameterCount();              // print parameter count            System.out.println(                cons[i].toGenericString()                + "-> parameter count = " + params);        }    }} |
Output:
public java.util.ArrayList(java.util.Collection)-> parameter count = 1 public java.util.ArrayList()-> parameter count = 0 public java.util.ArrayList(int)-> parameter count = 1
References: https://docs.oracle.com/javase/10/docs/api/java/lang/reflect/Constructor.html#getParameterCount()
