android - Can't check if file on sdcard exists -

i'm trying make simple check if file exist. saw similar questions here, didn't help. when run application, app crashes , got message "unfortunatelly, filecheck1 has stopped". got error both on emulator , smartphone.

my code:

package com.example.filecheck1;  import android.app.activity; import android.os.bundle; import android.os.environment; import android.widget.textview;  import java.io.file;  public class myactivity extends activity {      textview msgtext;     @override     public void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.main);          msgtext = (textview) findviewbyid(r.id.textview);         string path = environment.getexternalstoragedirectory().getpath()+"/ping.xml";         file file = getbasecontext().getfilestreampath(path);         if(file.exists()){             msgtext.settext("found");         }         if(!file.exists()){             msgtext.settext("not found");         }     } } 

in manifest such permissions:

<uses-permission android:name="android.permission.internet"></uses-permission> <uses-permission android:name="android.permission.write_external_storage"></uses-permission> 

thanks in advance.

i think problem here:

getbasecontext() 

where assigned null. don't need line. can achieve goal with

string path = environment.getexternalstoragedirectory().getpath() + "/ping.xml"; file f = new file(path); if (f.exists()) {    // stuff } else {   // stuff } 

update:

if or else have samsung galaxy s3, please follow @raghunandan's answer because in case getexternalstoragedirectory() returns internal memory.