how to check file exist on sd card or not

i have a activity where i have a image view..i capture image and image get stored in sd card folder. at the time of capterd image a folder will create in sd card and the respective clicked image stored in sd card card folder. And absolute path of that image inserted in sqlite database. i get the table index of image and split the path to get file/image name..,,i want to know how to check that image name exist in sd card folder or not at the time of post image to server..

String trp=AppDBManager.w1; ///image name get in Aapdbmanager class variable w1
File sdCard = Environment.getExternalStorageDirectory(); File dir = new File(Environment.getExternalStorageDirectory()+ "/Retailsolution/"+trp+"");

    if(dir.exists()){

        //code 

}