Android 随机生成4位数 仿验证码

 final TextView textView= (TextView) findViewById(R.id.text);
      textView.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View v) {
              Random random = new Random();
              Set set = new HashSet();
              while (set.size() < 4)
              {
                  int randomInt = random.nextInt(10);
                  set.add(randomInt);
              }
              StringBuffer sb = new StringBuffer();
              for (Integer i : set)
              {
                  sb.append("" + i);
              }
              textView.setText(sb.toString());
          }
      });