Validate Downloaded file after clicking on downloaded button/ link

gistfile1.txt

https://stackoverflow.com/questions/45573483/how-to-check-downloaded-files-selenium-webdriver
http://www.seleniumeasy.com/selenium-tutorials/verify-file-after-downloading-using-webdriver-java
https://stackoverflow.com/questions/30726126/detecting-a-file-downloaded-in-selenium-java

public class FileDownloadVerify {
	
	private WebDriver driver;
	
	private static String downloadPath = "D:\\seleniumdownloads";
	private String URL="http://spreadsheetpage.com/index.php/file/C35/P10/"; 
	
	@BeforeClass
	public void testSetup() throws Exception{
		driver = new FirefoxDriver(firefoxProfile());	
		driver.manage().window().maximize();
	}
	
	@Test
	public void example_VerifyDownloadWithFileName()  {
		driver.get(URL);
	    driver.findElement(By.linkText("mailmerge.xls")).click();
	    Assert.assertTrue(isFileDownloaded(downloadPath, "mailmerge.xls"), "Failed to download Expected document");
	}
	
        @Test
	public void example_VerifyDownloadWithFileExtension()  {
		driver.get(URL);
	    driver.findElement(By.linkText("mailmerge.xls")).click();
	    Assert.assertTrue(isFileDownloaded_Ext(downloadPath, ".xls"), "Failed to download document which has extension .xls");
	}

	@Test
	public void example_VerifyExpectedFileName() {
		driver.get(URL);
	    driver.findElement(By.linkText("mailmerge.xls")).click();
	    File getLatestFile = getLatestFilefromDir(downloadPath);
	    String fileName = getLatestFile.getName();
	    Assert.assertTrue(fileName.equals("mailmerge.xls"), "Downloaded file name is not matching with expected file name");
	}
	

	@AfterClass
	public void tearDown() {
		driver.quit();
	}