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()
