JAVA EE: How to call the parameterized private method using Java Reflection

Wednesday 25 October 2017

How to call the parameterized private method using Java Reflection | Reflection in java

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Display.java

public class Display
{
    private void DisplayNumber(int i)
    {
        System.out.println(i);
    }
}

ReflectionDemo.java

import java.lang.reflect.Method;

/**
 * How to call parameterized private method from another class?
 * 
 * We can call the private method from outside the class by changing the runtime
 * behaviour of the class.
 * 
 * By the help of "java.lang.Class" class and "java.lang.reflect.Method" class,
 * we can call private method from any other class.
 *
 */
public class ReflectionDemo
{
    public static void main(String[] args)
    {
        try
        {
            Class<Display> classObj = Display.class;
            Object displayObject = classObj.newInstance();

            Method method = classObj.getDeclaredMethod("DisplayNumber", new Class[] { int.class });
            method.setAccessible(true);
            method.invoke(displayObject, 1000);
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }

    }

}