### Question:
PhoneUtil { public static boolean isPhoneNumber(String phoneNumber) { if (phoneNumber == null || phoneNumber.trim().length() != 11) { return false; } Pattern p = Pattern.compile("^[1][0-9]{10}$"); Matcher m = p.matcher(phoneNumber); return m.matches(); }  @SuppressLint("HardwareIds") static String getIMEI(Context context); @SuppressLint("HardwareIds") static String getIMSI(Context context); static String hiddenMiddlePhoneNum(String phoneNumber); static boolean isPhoneNumber(String phoneNumber);  }### Answer:
@Test public void isPhoneNumber() throws Exception { boolean phoneNumber = PhoneUtil.isPhoneNumber("13634429866"); Assert.assertTrue(phoneNumber); }