collection.shuffle does not work in java netbeans 8.2

I am trying to shuffle JButton using collections.shuffle(),but it does not work when I run the program…

this is my code :

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    package projetu;
    import java.awt.*;
    import java.util.*;
     * @author USER
    public class NewMain extends JFrame{
         * @param args the command line arguments
           final int row =3;
           final int col =3;
           javax.swing.JPanel panel;
           javax.swing.JButton button[];
           List<javax.swing.JButton> arrlist = new ArrayList();

        public NewMain (){
            panel = new javax.swing.JPanel();
            panel.setLayout(new GridLayout(row,col));
        button = new javax.swing.JButton[9];
        for (int i=0; i<9; i++){
            button[i] = new javax.swing.JButton(String.valueOf(i));
        } //end of script 0001
             public static void main(String[] args) {
            // TODO code application logic here
            NewMain n=new NewMain();