How to check if a jframe is opened?

Question

My code below create a new array and sends it to chat(jFrame).

String info1[]=new String[3];
 // username , userid , userid2 are variables
 info1[0]=username4;
 info1[1]=""+userid;
 info1[2]=""+userid2;

 chat.main(info1);

But i need to modify this code to work such a way that it , if the chat jframe was opened, then dont open a new jFrame .But instead open a new tab in chat jframe . The code for chat frame is :

private void formWindowActivated(java.awt.event.WindowEvent evt) {       
  JScrollPane panel2 = new JScrollPane();
  JTextArea ta=new JTextArea("");
  ta.setColumns(30);
  ta.setRows(19);
  panel2.setViewportView(ta);
  jTabbedPane1.add("Hello", panel2);   
}

Hostetter

I swear to god I saw this same question earlier today. Have you tried searching this? – Fetich

See also - The Use of Multiple JFrames, Good/Bad Practice? – Benevolence

Answer 1

I wonder if you shouldn't be using JDialogs instead of JFrames, if the window is dependent on another window.

A solution is to use a class field to hold a reference to the window (JFrame or JDialog) and checking if it is null or visible, and if so, then lazily create/open the window,

public void newChat(User user) {
  if (chatWindow == null) {
    // create chatWindow in a lazy fashion
    chatWindow = new JDialog(myMainFrame, "Chat", /* modality type */);
    // ...  set up the chat window dialog
  }

  chatWindow.setVisible(true);
  addTabWithUser(user);
}

but that's about all I can say based on the information provided. If you need more specific help, then you will need to provide more information.

Honduras

Thank you for giving me the idea of JDialog. – Hostetter

Answer 2

If using JFrames it can be simply done like this:

if (Frame1.component != null) {
   Frame1 is opened
} else if (Frame2.component == null) {
   Frame2 is closed
}

Component ex.JTextField, JComboBox etc.

Direful

getting "error: component has private access in Container" – Trueblood

Answer 3

this is old but i would like to share how i handle this kind of requirement:

import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;

public class multipleFrames extends JFrame {
    
    static JFrame mainFrame;
    static JFrame secondFrame;

    public multipleFrames() {
        // TODO Auto-generated constructor stub

    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        // Create the main frame
        openMainFrame();

    }

    protected static void openSecondFrame() {
        // TODO Auto-generated method stub
        secondFrame = new JFrame("Second Frame");
//      secondFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        secondFrame.setSize(400, 200);
        secondFrame.setLayout(new FlowLayout());
        secondFrame.setLocationRelativeTo(mainFrame);
        secondFrame.getContentPane().setBackground(Color.decode("#3d8500"));
        secondFrame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                JOptionPane.showMessageDialog(secondFrame,"Disposing secondFrame ...","Message",JOptionPane.PLAIN_MESSAGE);
                secondFrame.dispose();
                // clear secondFrame references to destroy it
                secondFrame = null;
            }
        });

        // Create buttons
        JButton backButton = new JButton("Back to Main Frame");
        backButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
//              secondFrame.setVisible(false);
                if (mainFrame==null) {
                    JOptionPane.showMessageDialog(secondFrame,"mainFrame not exist, creating ...","Message",JOptionPane.PLAIN_MESSAGE);
                    openMainFrame();
                }else {
                    mainFrame.setVisible(true);
                    mainFrame.toFront();
                }

            }
        });
        secondFrame.add(backButton);

        secondFrame.setVisible(true);
        
    }

    protected static void openMainFrame() {
        // TODO Auto-generated method stub
        mainFrame = new JFrame("Main Frame");
//        mainFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        mainFrame.setSize(400, 200);
        mainFrame.setLayout(new FlowLayout());
        mainFrame.setLocationRelativeTo(secondFrame);
        mainFrame.getContentPane().setBackground(Color.decode("#3d85c6"));
        mainFrame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                JOptionPane.showMessageDialog(mainFrame,"Disposing mainFrame ...","Message",JOptionPane.PLAIN_MESSAGE);
                mainFrame.dispose();
                // clear manFrame references to destroy it
                mainFrame = null;
            }
        });
        
        // Create buttons
        JButton secondButton = new JButton("Open Second Frame");
        secondButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
//              mainFrame.setVisible(false);
                if (secondFrame==null) {
                    JOptionPane.showMessageDialog(mainFrame,"secondFrame not exist, creating ...","Message",JOptionPane.PLAIN_MESSAGE);
                    openSecondFrame();
                }else {
                    secondFrame.setVisible(true);
                    secondFrame.toFront();
                }

            }
        });
        mainFrame.add(secondButton);
        
        mainFrame.setVisible(true);
        
    }

}

Dagney

Maybe you could make the code in your answer a minimal reproducible example? As it stands, I don't think it would compile since I can't find the declaration of variable otherframe in class myFrame. By the way, when posting code on SO, it is recommended to adhere to Java naming conventions. – Bowman