ایجاد رمز تصادفی

 final TextView tv=(TextView)findViewById(R.id.textView77);
 Button b1=(Button)findViewById(R.id.button);
 b1.setOnClickListener(new View.OnClickListener() {
 @Override
 public void onClick(View view) {

 int random_string_length = 14;
 String[] all_characters = {
 "a","b","c","d","e","f","g","h","i","j","k","l","m",
 "n","o","p","q","r","s","t","u","v","w","x","y","z",
 "0","1","2","3","4","5","6","7","8","9",
 " "
 };
 int all_characters_length = all_characters.length;

 int min = 0;
 int max = all_characters_length-1;


 for(int x = 1; x < random_string_length+1; x = x+1) {
 Random r = new Random();
 int random_number = r.nextInt(max - min + 1) + min;
 String random_character = all_characters[random_number];
 random_string = random_string + random_character;
 tv.setText(random_string);
 }
 }


 });
tv.setText("");

با سلام 

این متد میتونه کمکتون کنه

 public String getPassword(int len) {
     String chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
     StringBuilder pass = new StringBuilder();
     Random rnd = new Random();
     while (pass.length() < len) { 
         int index = (int) (rnd.nextFloat() * chars.length());
         pass.append(chars.charAt(index));
     }
     return pass.toString();
 }

در ضمن شما میتونید در رشته chars هر کارکتری که میخواهید ازش در پسورد استفاده بشه رو وارد کنید!