Android判断APP是否第一次启动

SharedPreferences setting = getSharedPreferences(SHARE_APP_TAG, 0);
Boolean user_first = setting.getBoolean("FIRST",true);
if(user_first){//第一次
      setting.edit().putBoolean("FIRST", false).commit();
      Toast.makeText(MainActivity.this, "第一次", Toast.LENGTH_LONG).show();
 }else{
     Toast.makeText(MainActivity.this, "不是第一次", Toast.LENGTH_LONG).show();
}