asked on

read java file

i`m trying to write a program that able to read a java file
and output a result to tell how many methods in the particular file.
for example:

public class Hello
{
int x;
Hello()
{

}

public static void main(String args[ ])
{

}

public void A( )
{

}

public void B()
{

}

}
output: 4 methods
-Hello
-main
-A
-B

can anyone please tell me how to to do?

Ravindra76

It will list Object methods also.

I will send later another version

import java.lang.reflect.*;

class GetMethods {

      public static void main(String args[]){

            try {
                  Hello obj = new Hello();
                  Class hello = obj.getClass();
                  Method methods[] = hello.getMethods();
                  for ( int i=0; i < methods.length; i++ ) {
                        System.out.println("Method "+(i+1)+"="+methods[i]);
                  }
            }
            catch ( Exception ee){
                  ee.printStackTrace();
            }
      }
}

Ravindra76

import java.lang.reflect.*;

class GetMethods {

      public static void main(String args[]){

            try {
                  Hello obj = new Hello();
                  Class hello = obj.getClass();
                  String cname = hello.getName();
                  System.out.println("Class Name="+cname);

                  Constructor constructors[] = hello.getConstructors();
                  System.out.println("Constructors="+constructors.length);
                  for ( int i=0; i < constructors.length; i++ ) {
                        String cons = constructors[i].toString();
                  //      if ( cons.indexOf(cname) > 0)
                        System.out.println("Constructor "+(i+1)+"="+cons);

                  }


                  Method methods[] = hello.getMethods();

                  for ( int i=0; i < methods.length; i++ ) {
                        String method = methods[i].toString();
                        if ( method.indexOf(cname) > 0)
                        System.out.println("Method "+(i+1)+"="+method);
                  }
            }
            catch ( Exception ee){
                  ee.printStackTrace();
            }
      }
}

Ravindra76

Read documentation for

java.lang.Class and java.lang.reflect package

Ravindra76

Ok.

From the output it is sure that

Java Interpreter is not treating

default constructor ( Hello () ) as a constructor.

That's why You got zero constructors

Ravindra76

ravindra76 changed the proposed answer to a comment

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wongww

ASKER

i have one problem!!My program have to open ANY type of standard .java file to read it using FileDialog.
In ur program u have declare an object for the particular class that u wanted to read.How can I do that in my case??

Ravindra76

import java.lang.reflect.*;
import java.lang.*;

class GetMethods {

      public static void main(String args[]){

            try {

                  Class hello = Class.forName(args[0]);
                  String cname = hello.getName();
                  System.out.println("Class Name="+cname);

                  Constructor constructors[] = hello.getConstructors();
                  System.out.println("Constructors="+constructors.length);
                  for ( int i=0; i < constructors.length; i++ ) {
                        String cons = constructors[i].toString();
                  //      if ( cons.indexOf(cname) > 0)
                        System.out.println("Constructor "+(i+1)+"="+ constructors[i].getName());

                  }


                  Method methods[] = hello.getMethods();

                  for ( int i=0; i < methods.length; i++ ) {
                        String method = methods[i].toString();
                        if ( method.indexOf(cname) > 0)
                        System.out.println("Method "+(i+1)+"="+methods[i].getName());
                  }
            }
            catch ( Exception ee){
                  ee.printStackTrace();
            }
      }
}
/*
java.io.File has getName() function.

Get the file name and substitute it in the palce of args[0]

That's all

:)*/

wongww

ASKER

I have follow ur code.But it is not working!!Got run time error. Can u please tell me why??
Heres my code:

import java.lang.reflect.*;
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import java.lang.*;
import java.util.*;

public class Display extends Frame implements ActionListener
{

int num_arr;
int num_array;
String filename;

public Display() //constructor
{
super();
setSize(400,300);
setTitle("");
addWindowListener(new WindowDestroyer());

Menu mb = new Menu("File");
MenuItem m;
m = new MenuItem("Open");
m.addActionListener(this);
mb.add(m);
m = new MenuItem("Close");
m.addActionListener(this);
mb.add(m);
m = new MenuItem("Exit");
m.addActionListener(this);
mb.add(m);

MenuBar mBar = new MenuBar();
mBar.add(mb);

setMenuBar(mBar);
}

public void actionPerformed(ActionEvent e)
{
try
{
String actionCommand = e.getActionCommand();
Dialog dl;
Label l;

if(actionCommand.equals("Open"))
{
FileDialog fd=new FileDialog(f,"Open Image file",FileDialog.LOAD);
fd.setVisible(true);
String fname=fd.getFile();
String fdir=fd.getDirectory();
String fn=fd.getName();

if((fname!=null && fname.indexOf(".JAVA")>0) || (fname!=null && fname.indexOf(".java")>0))
{
try{

Class hello = Class.forName(fn);
String cname = hello.getName();
System.out.println("Class Name="+cname);

}

catch ( Exception ee){
ee.printStackTrace();
}
}
} //end if
else if(actionCommand.equals("Close"))
{

} //end if

else if(actionCommand.equals("Exit"))
{
System.exit(0);
} // end if

} catch (NullPointerException e1) {}
}

public static void main(String[] args)
{
f=new Display();
f.setVisible(true);
f.setTitle("DISPLAY");
}//end main

static Display f = new Display();
Panel center=new Panel();

}//end class

Ravindra76

The correct version:_

import java.lang.reflect.*;
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import java.lang.*;
import java.util.*;

public class Display extends Frame implements ActionListener
{

int num_arr;
int num_array;
String filename;

public Display() //constructor
{
super();
setSize(400,300);
setTitle("");
//addWindowListener(new WindowDestroyer());

Menu mb = new Menu("File");
MenuItem m;
m = new MenuItem("Open");
m.addActionListener(this);
mb.add(m);
m = new MenuItem("Close");
m.addActionListener(this);
mb.add(m);
m = new MenuItem("Exit");
m.addActionListener(this);
mb.add(m);

MenuBar mBar = new MenuBar();
mBar.add(mb);

setMenuBar(mBar);
}

public void actionPerformed(ActionEvent e)
{
try
{
String actionCommand = e.getActionCommand();
Dialog dl;
Label l;

if(actionCommand.equals("Open"))
{
FileDialog fd=new FileDialog(f,"Open Image file",FileDialog.LOAD);
fd.setVisible(true);
String fname=fd.getFile();
       fname = fname.substring(0,fname.length()-5);
System.out.println("File name="+fname);

if(fname!=null )
{
try{

Class hello = Class.forName(fname);
String cname = hello.getName();
System.out.println("Class Name="+cname);

}

catch ( Exception ee){
ee.printStackTrace();
}
}
} //end if
else if(actionCommand.equals("Close"))
{

} //end if

else if(actionCommand.equals("Exit"))
{
System.exit(0);
} // end if

} catch (NullPointerException e1) {}
}

public static void main(String[] args)
{
f=new Display();
f.setVisible(true);
f.setTitle("DISPLAY");
}//end main

static Display f = new Display();
Panel center=new Panel();

}//end class

/* IMPORTANT:-The file You are selecting must be compiled before U run this program.
Because we are loading the Class object
which will execute when THe .java file is
compiled...SO be sure that , the file u are selecting from FileDialog must be compiled
      and .class file should be present in same directory.:)

In the code , You selected .java file from Dialog. But be sure that .class should be present
for that .java file.

If You select .class file directly in filedialog,
Replace

       fname = fname.substring(0,fname.length()-5);

with
            fname = fname.substring(0,fname.length()-6);

*/

:)

wongww

ASKER

Thankz!

wongww

ASKER

Adjusted points from 100 to 150