Java tutorial
//package com.java2s; import android.os.Environment; import android.text.TextUtils; import java.io.*; public class Main { public static String getRootByApi() { if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) { File file = Environment.getExternalStorageDirectory(); if (file == null) return null; String path = file.getAbsolutePath(); if (isValidRoot(path)) return path; } return null; } public static boolean isValidRoot(String root) { if (TextUtils.isEmpty(root)) return false; File rootFile = new File(root); return rootFile.exists() && rootFile.canRead() && rootFile.canWrite(); } }