Populate a 2d array with random alphabetic values in Java

import java.util.Arrays;
import java.util.Random;
public class Demo {
	public static void main(String[] args) {
		char arr[][] = new char[3][3];
		Random randNum = new Random();
		for (int i = 0; i< 3; i++) {
			for (int j = 0; j< 3; j++) {
				int x = randNum.nextInt(3);
				switch (x) {
					case 0: {
						arr[i][j] = 'p';
						break;
					}
					case 1: {
						arr[i][j] = 'q';
						break;
					}
					case 2: {
						arr[i][j] = 'r';
						break;
					}
					case 3: {
						arr[i][j] = 's';
						break;
					}
					case 4: {
						arr[i][j] = 't';
						break;
					}
					case 5: {
						arr[i][j] = 'u';
						break;
					}
					case 6: {
						arr[i][j] = 'v';
						break;
					}
					case 7: {
						arr[i][j] = 'w';
						break;
					}
				}
			}
		}
		System.out.println("Random alphabets...");
		System.out.println(Arrays.deepToString(arr));
	}
}