Creating a program that works as javap tool

Following methods of java.lang.Class class can be used to display the metadata of a class.

Method	Description
public Field[] getDeclaredFields()throws SecurityException	returns an array of Field objects reflecting all the fields declared by the class or interface represented by this Class object.
public Constructor[] getDeclaredConstructors()throws SecurityException	returns an array of Constructor objects reflecting all the constructors declared by the class represented by this Class object.
public Method[] getDeclaredMethods()throws SecurityException	returns an array of Method objects reflecting all the methods declared by the class or interface represented by this Class object.

Example of creating javap tool

Let's create a program that works like javap tool.

import java.lang.reflect.*;

public class MyJavap{
   public static void main(String[] args)throws Exception {
	Class c=Class.forName(args[0]);
	
	System.out.println("Fields........");
	Field f[]=c.getDeclaredFields();
	for(int i=0;i<f.length;i++)
		System.out.println(f[i]);
	
	System.out.println("Constructors........");
	Constructor con[]=c.getDeclaredConstructors();
	for(int i=0;i<con.length;i++)
		System.out.println(con[i]);
	
        System.out.println("Methods........");
	Method m[]=c.getDeclaredMethods();
	for(int i=0;i<m.length;i++)
		System.out.println(m[i]);
   }
}

At runtime, you can get the details of any class, it may be user-defined or pre-defined class.