Como gero um numero randomico?

n = new int[10];
           
            x = random.nextInt(99);

                  
            n[1] = random.nextInt(10);
            n[3] = random.nextInt(10);
            n[5] = random.nextInt(10);
            n[7] = random.nextInt(10);
            n[9] = random.nextInt(10);
                
            n[2] = random.nextInt(10);
            n[4] = random.nextInt(10);
            n[6] = random.nextInt(10);
            n[8] = random.nextInt(10);
            
            sum1 = n[1] + n[3] + n[5] + n[7] + n[9];
            sum2 = n[2] + n[4] + n[6] + n[8];

            s = x - sum1;
            n[10] = s - sum2;

nesta parte

s = x - sum1;

n[10] = s - sum2;

x = random.nextInt(99);

int x = random.nextInt(99);

while (x<10) {
 x = random.nextInt(99);
}

tenta ai

[]'s

String string = String.valueOf( n[i] );

/*
 * HelloMIDlet.java
 *
 * Created on 2 de Março de 2005, 15:55
 */

package hello;

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import java.util.Random;

/**
 * An example MIDlet with simple "Hello" text and an Exit command.
 * Refer to the startApp, pauseApp, and destroyApp
 * methods so see how each handles the requested transition.
 *
 * @author  Felipe
 * @version
 */
public class HelloMIDlet extends MIDlet implements CommandListener {
    
    private Command exitCommand, gerarCommand; // The exit command
    private Display display;    // The display for this MIDlet
    int n[];
    Random random = new Random(19857);
    int sum1, sum2;
    String strchave;
            
           
    public HelloMIDlet() {
        display = Display.getDisplay(this);
        exitCommand = new Command("Sair", Command.SCREEN, 2);
        gerarCommand = new Command("Gerar", Command.SCREEN, 3);
    }
    
    /**
     * Start up the Hello MIDlet by creating the TextBox and associating
     * the exit command and listener.
     */
    public void startApp() {
        TextBox t = new TextBox("Gerador de Seriais ", "String de Teste", 256, 0);
        
        t.addCommand(exitCommand);
        t.addCommand(gerarCommand);
        t.setCommandListener(this);
        
        display.setCurrent(t);
    }
    
    /**
     * Pause is a no-op since there are no background activities or
     * record stores that need to be closed.
     */
    public void pauseApp() {
    }
    
    /**
     * Destroy must cleanup everything not handled by the garbage collector.
     * In this case there is nothing to cleanup.
     */
    public void destroyApp(boolean unconditional) {
    }
    
    /*
     * Respond to commands, including exit
     * On the exit command, cleanup and notify that the MIDlet has been destroyed.
     */
    public void commandAction(Command c, Displayable s) {
        if (c == exitCommand) {
            destroyApp(false);
            notifyDestroyed();
        }

        if (c == gerarCommand) {
            n = new int[10];
                
            n[1] = random.nextInt(10);
            n[3] = random.nextInt(10);
            n[5] = random.nextInt(10);
            n[7] = random.nextInt(10);
            n[9] = random.nextInt(10);
                
            n[2] = random.nextInt(10);
            n[4] = random.nextInt(10);
            n[6] = random.nextInt(10);
            n[8] = random.nextInt(10);
            
            sum1 = n[1] + n[3] + n[5] + n[7] + n[9];
            sum2 = n[2] + n[4] + n[6] + n[8];

            int x = random.nextInt(99); 

            while (x<10) { 
                x = random.nextInt(99); 
            } 
            
           int y = x - sum1;
           
           n[10] = y - sum2;
           
           Alert alert = new Alert("Chave de Liberacao");
           alert.setTimeout(Alert.FOREVER);
           
           strchave = 'C' + String.valueOf(n[1]) + String.valueOf(n[2]) +
           String.valueOf(n[3]) + String.valueOf(n[4]) + String.valueOf(n[5]) + String.valueOf(n[6])
           + String.valueOf(n[7]) + String.valueOf(n[8]) + String.valueOf(n[9]) + String.valueOf(n[10])
           + String.valueOf(x);
           
           alert.setString(strchave);
                   
        }
    }
    
}