How do I display an array of Buttons on to a JScrollPane?

Question

I am trying to create an array of buttons and put them in a scroll box, but nothing gets displayed. Also, how do I add an action listener?

JPanel buttons4Contacts = new JPanel();
buttons4Contacts.setLayout(new GridLayout(5, 5));

for (User user: Network.usersList){ //Make a JButton for every contact.
    JButton button = new JButton(user.getName());
    button.setPreferredSize(new Dimension(100,100));
    buttons4Contacts.add(button);
}

JPanel contactButtonHolder = new JPanel(new FlowLayout(FlowLayout.CENTER, 0,0));
contactButtonHolder.add(buttonsforContacts);
contacts = new JScrollPane(contactButtonHolder);

contacts.add(buttons4Contacts);
contacts.setPreferredSize(new Dimension(200,200));
rightPanelSouth.add(contacts);

Put the buttons in a panel and add the panel to the scroll pane. *"Also, how do I add an action listener?"* SO is not a help-desk, but a Q&A site. As such, that should be on a separate question. — Andrew Thompson, Dec 13 '14 at 01:10
For better help sooner, post an [MCVE](http://stackoverflow.com/help/mcve) (Minimal Complete Verifiable Example) or [SSCCE](http://www.sscce.org/) (Short, Self Contained, Correct Example). — Andrew Thompson, Dec 13 '14 at 01:10
`contacts.setPreferredSize(new Dimension(200,200));` See [Should I avoid the use of set(Preferred|Maximum|Minimum)Size methods in Java Swing?](http://stackoverflow.com/q/7229226/418556) (Yes.) — Andrew Thompson, Dec 13 '14 at 01:13

score 1 · Answer 1 · answered Dec 13 '14 at 10:18

As other friends have previously mentioned you can create a Panel,add all the buttons in the panel and finally add scrollbar to the panel.

here is my simple code that does the job:

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;

public class ArrayOfButtons extends JFrame{

    final static int numberOfButtons=5;   

    // Label to display the message indicating which button generated the event.

    JLabel label=new JLabel();

    // Panel to accomodate the labels

    JPanel panel=new JPanel(); 

    //We create an array of buttons whose number depends on our choice  

    JButton buttons[]=new JButton[numberOfButtons]; 

public ArrayOfButtons(){
    super("Demo");

    //We create an instance of the class ButtonHandler which implements the interface
    //ActionListener. And this object "handler" is basically the object that handles 
    //the events.            

    ButtonHandler handler=new ButtonHandler();  

    //Using a for loop we create JButtons.    

    for(int i=0;i<numberOfButtons;i++){
        buttons[i]=new JButton("Button"+i);

        // here we register handler as the event listener for all the buttons.i.e if in 
        // case an event occurs in any of the buttons, the event listener (in our case
        //the handler object) calls an appropriate method that handles the event.            

        buttons[i].addActionListener(handler);

        // add each button to the panel

        panel.add(buttons[i]);
    }

   // we add the label to the JFrame 
   add(label,BorderLayout.SOUTH);
   // we add ScrollPane to the JFrame and in turn add Panel to the ScrollPane.
   add(new JScrollPane(panel));      
}

// This is an inner class that handles the events.(Look more on inner classes).

 public class ButtonHandler implements ActionListener{   

    //This method is called in case an action event occurs.For example you click on the
    //button      
     public void actionPerformed(ActionEvent event){

         // gets the name of the button and displays in the label.

         label.setText(event.getActionCommand());

     }       
}
}

Add a main method of your own, and the code will work just fine. Hope this will help.

How do I display an array of Buttons on to a JScrollPane?

1 Answers1