JAVA EE: How to get the parameter count of method using Java Reflection

Thursday, 2 November 2017

How to get the parameter count of method using Java Reflection | Reflection in java

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DisplayMessage.java

class DisplayMessage
{
    
    public void displayMessage(String message)
    {
        System.out.println(message);
    }
}

ReflectionDemo.java

import java.lang.reflect.Method;

/**
 * 
 * How to get method parameter count.
 *
 */
public class ReflectionDemo
{
    public static void main(String[] args)
    {
        Class<DisplayMessage> classObj = DisplayMessage.class;
        Method[] methodArray = classObj.getMethods();
        for (Method method : methodArray)
        {
            System.out.println(method);
            System.out.println("Parameter Count = "+method.getParameterCount());
            System.out.println("---------------------------");
        }
    }

}

Output

public void DisplayMessage.displayMessage(java.lang.String)
Parameter Count = 1
---------------------------
public final void java.lang.Object.wait() throws java.lang.InterruptedException
Parameter Count = 0
---------------------------
public final void java.lang.Object.wait(long,int) throws java.lang.InterruptedException
Parameter Count = 2
---------------------------
public final native void java.lang.Object.wait(long) throws java.lang.InterruptedException
Parameter Count = 1
---------------------------
public boolean java.lang.Object.equals(java.lang.Object)
Parameter Count = 1
---------------------------
public java.lang.String java.lang.Object.toString()
Parameter Count = 0
---------------------------
public native int java.lang.Object.hashCode()
Parameter Count = 0
---------------------------
public final native java.lang.Class java.lang.Object.getClass()
Parameter Count = 0
---------------------------
public final native void java.lang.Object.notify()
Parameter Count = 0
---------------------------
public final native void java.lang.Object.notifyAll()
Parameter Count = 0
---------------------------