A small doubt

[Hari Mohanan]

I am a beginner in java. So I have a small doubt....compare these two classes:

Marks Analysis class

 import javax.swing.* ;
import java.awt.* ;
import java.awt.event.*;
import javax.swing.border.*;

public class MarkAnalysis implements ActionListener{ 
	
	JFrame frame = new JFrame("::Marks Analysis::") ;
	JLabel loginLabel = new JLabel("Enter the security PIN Number:: ") ;
	JTextField field = new JTextField(4) ;
	JPanel login = new JPanel() ;
	JPanel markan = new JPanel() ;
	Font f = new Font("segoi ui", Font.BOLD, 14) ;	
	JLabel mainLabel = new JLabel("Welcome to Marks Analysis!") ;
	
	public void DoTheMagic() {
		
		frame.getContentPane().add(BorderLayout.WEST, login) ;
        frame.getContentPane().add(BorderLayout.NORTH, markan) ;
        
        field.addActionListener(this) ;
		
		login.add(loginLabel) ;
		login.add(field) ;
		login.setBackground(Color.gray) ;
		markan.setBackground(Color.white) ;
		markan.add(mainLabel) ;
		mainLabel.setFont(f) ;
		
		mainLabel.setBorder(BorderFactory.createEtchedBorder(10, Color.BLACK, Color.gray)) ;
	
		frame.setSize(400,300) ;
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) ;
		frame.setVisible(true) ;
		
		field.requestFocus() ;
	}
	
	public void actionPerformed(ActionEvent ev) {
		
		int n = 0 ;
		String sn = field.getText() ;
		try{
			n = Integer.parseInt(sn) ;
		}
		catch(Exception e){
			e.printStackTrace() ;
			JOptionPane.showMessageDialog(null, "Please enter numerals!", "Error!", JOptionPane.ERROR_MESSAGE) ;
		}
		if(n == 6973)
			JOptionPane.showMessageDialog(null, "Authenticating...success!", "Loggin in...", JOptionPane.INFORMATION_MESSAGE) ;
		else
			JOptionPane.showMessageDialog(null, "Authenticating...invalid PIN!", "Logging in...", JOptionPane.INFORMATION_MESSAGE) ;
	}
}



   

Marks Pages class

  import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class MarkPages ActionListener {

	
}  

Now my doubt is, if I inherit MarkPages from MarkAnalysis, can I modify the values of the JFrame 'frame'? That is, the components in the previous class will not be used, instead I only give a new form to the existing JFrame 'frame'. According to my knowledge, 'frame' is an object of class JFrame. So can an object's state be inherited? (Sorry for using confusing sentences, i am a newbie)

[Campbell Ritchie]

Don't understand the question; you have posted difficult code to read.

Moving to our GUIs forum.

[Hari Mohanan]

what i am trying to say it, can i use the same JFrame (frame) as common for both the classes without defining a new one..

[pete stein]

Hari Mohanan wrote:
Now my doubt is, if I inherit MarkPages from MarkAnalysis, can I modify the values of the JFrame 'frame'? That is, the components in the previous class will not be used, instead I only give a new form to the existing JFrame 'frame'. According to my knowledge, 'frame' is an object of class JFrame. So can an object's state be inherited? (Sorry for using confusing sentences, i am a newbie)

No, that is not what inheritance is for, for one, and for two, it simply won't work. Whenever you consider having one class extend another you must ask yourself is the child class a more specialized version of the parent class, for instance, a Dog a more specialized instance of an Animal, but Bark is not a more specialized version of Dog. The next issue is, even if it's not right, will it work? and the answer is no, it will not, since each class will own its own separate JFrame instance that are completely unrelated to each other.

The solution is to pass a reference of one class to the other.

[Hari Mohanan]

Thanks a lot for clearing my doubt, but can you tell me how to pass the reference?

[Michael Dunn]

> but can you tell me how to pass the reference?

really, that's on about page 1 of any beginner's book.