import java.util.ArrayList;
import java.util.Random;
import java.util.Collections;

public class Tester{

?ArrayList <String> string = new ArrayList<String>();
?Random random = new Random();
?
?public static void main(String [] args){
??Tester tester = new Tester();
??tester.sort();
??System.out.println("********Before sort*******");
??for(int i = 0;i < tester.string.size(); i++){
???System.out.println(tester.string.get(i));
??}
??System.out.println("********After sort*******");
??Collections.sort(tester.string);
??for(String temp: tester.string){
???System.out.println(temp);
??}
?}

?public void sort(){
??String s = "";
??for(int i = 0; i < 10; i++){
???
???do{
???s = createString();
???}while(string.contains(s));
???System.out.println("Element: "+s);
???string.add(s);
??}
??
??
?}
?
?public String createString(){
??
??String str = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
??
??StringBuilder sb = new StringBuilder();
??int number = (random.nextInt(9)+1);
??do{
???sb.append(str.charAt(random.nextInt(str.length())));
???number--;
??}while(number >0);
???return sb.toString();
?}

}