Creating a program that works as javap tool (Reflection Session-4)

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.

1.    import java.lang.reflect.*;  

2.      

3.    public class MyJavap{  

4.       public static void main(String[] args)throws Exception {  

5.        Class c=Class.forName(args[0]);  

6.          

7.        System.out.println("Fields........");  

8.        Field f[]=c.getDeclaredFields();  

9.        for(int i=0;i<f.length;i++)  

10.         System.out.println(f[i]);  

11.       

12.     System.out.println("Constructors........");  

13.     Constructor con[]=c.getDeclaredConstructors();  

14.     for(int i=0;i<con.length;i++)  

15.         System.out.println(con[i]);  

16.       

17.         System.out.println("Methods........");  

18.     Method m[]=c.getDeclaredMethods();  

19.     for(int i=0;i<m.length;i++)  

20.         System.out.println(m[i]);  

21.    }  

22. }  

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

Output: