Display random characters in grid

I have a piece of code to display an input string in shuffled order and also another code to display a simple grid.I am not sure how to integrate it though. I want the shuffled characters to sit in a random position in a grid and rest of the positions in the grid must be filled by random characters. How do I do it

//For drawing the grid

*import java.awt.GridLayout;
 import javax.swing.JFrame;
 import javax.swing.JLabel;
 import javax.swing.JPanel;
 public class DrawGrid 
 {
 public DrawGrid() 
 {
     int[][] grid = getGrid();
     Panel panel = new JPanel(new GridLayout(8,8));
     for (int i = 0; i < grid.length; i++) {
     for (int j = 0; j < grid[i].length; j++) {
     panel.add(new JLabel(String.valueOf(grid[i][j])));
  }
  }
  JFrame frame = new JFrame();
  frame.add(panel);
  frame.pack();
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  frame.setLocationRelativeTo(null);
  frame.setVisible(true);
}
public int[][] getGrid() {
    int[][] grid = new int[8][8];
    for (int i = 0; i < grid.length; i++) {
        for (int j = 0; j < grid[i].length; j++) {
            grid[i][j] = i;
        }
    }
    return grid;
}
public static void main(String[] args) {
    new DrawGrid();
}
}*

//to shuffle characters

 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 public class Main {

 public static void main(String[] args) throws Exception
 {
 ArrayList<String> obj = new ArrayList<String>();
 obj.add("G");
 obj.add("E");
 obj.add("O");
 obj.add("M");
 obj.add("E");
 obj.add("T");
 obj.add("R");
 obj.add("Y");
 Collections.shuffle(obj);
 System.out.println(obj);   //Prints the shuffled i/p string



 }   
 }