here is code show how to switch to next tab

switch_to_next_tab.java

package projectname.com.example;

import java.util.List;
import java.util.Set;

import junit.framework.Assert;

import org.openqa.selenium.WebElement;
import org.junit.After;
import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.Test;
import org.openqa.selenium.Alert;
import org.openqa.selenium.By;
import org.openqa.selenium.JavascriptExecutor;
import org.openqa.selenium.NoAlertPresentException;
import org.openqa.selenium.NoSuchElementException;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.interactions.Actions;
import org.openqa.selenium.support.ui.ExpectedCondition;
import org.openqa.selenium.support.ui.ExpectedConditions;
import org.openqa.selenium.support.ui.WebDriverWait;

public class AskMeWatch {
	// Declare a static driver variable
	private WebDriver driver;

	@BeforeClass
	public static void beforeClass() {
		System.setProperty("webdriver.chrome.driver", "/Users/ducnguyen/Workspace/chromedriver");
		// WebDriver driver = new ChromeDriver();

	}

	@Before
	public void setUp() throws Exception {
		this.driver = new ChromeDriver();
		this.driver.manage().window().maximize();
		// this.driver.get("https://askme.watch");
		Thread.sleep(5000);

	}

	// @Test
	public void watchAdvisor() throws InterruptedException {
		// click watch advisor tab
		clickButtonXpath("//*[@id='myNavbar']/ul[1]/li[1]/a");
		Thread.sleep(4000);
		// step 1
		clickButtonXpath("//div[@value='1']");
		clickButtonCss("#next-ans");
		// step 2
		clickButtonXpath(".//*[@id='quizarea']/div/div/div[2]/div/div[2]/div/div/div[1]/div");
		clickButtonCss("#next-ans");
		// step 3
		clickButtonXpath(".//*[@id='quizarea']/div/div/div[2]/div/div[3]/div/div/div[3]/div");
		clickButtonCss("#next-ans");
		// step 4
		clickButtonXpath(".//*[@id='quizarea']/div/div/div[2]/div/div[4]/div/div/div[1]/div");
		clickButtonCss("#next-ans");
		// step 5
		clickButtonXpath(".//*[@id='quizarea']/div/div/div[2]/div/div[5]/div/div/div[3]/div");
		clickButtonCss("#next-ans");
		// step 5
		clickButtonCss("#next-ans");
		// list results

		List<WebElement> listWatchAdvisor = driver.findElements(By.cssSelector(".watch-result div"));
		int r = listWatchAdvisor.size();
		if (r <= 0) {
			System.out.println("No results for watch advisor");
			return;
		} else {
			// click first element
			listWatchAdvisor.get(0).click();
		}
		// get url
		Thread.sleep(2000);
		// check URL consist of 'review-specifications-quote'
		checkConsistOFQuoteString();

	}

	// @Test
	public void priceFinder() throws InterruptedException {
		// click price finder tab
		clickButtonXpath(".//*[@id='myNavbar']/ul[1]/li[2]/a");
		// searching
		findXpath(".//*[@id='search-watch']").sendKeys("rolex");
		clickButtonXpath(".//*[@id='button-search']");
		Thread.sleep(5000);
		// paging
		// List<WebElement> listPaging = driver.findElements(By.cssSelector(".pagination
		// li"));
		// System.out.println(listPaging.size());
		// for (int i = 0; i < listPaging.size() - 3; i++) {
		// System.out.println("i:"+i);
		// // have problem can not click
		// clickButtonCss("a[rel=\"next\"]");
		// Thread.sleep(5000);
		// }
		WebElement link = findCss("a[rel=\"next\"]");
		while (link != null) {
			clickButtonCss("a[rel=\"next\"]");
			Thread.sleep(5000);
			link = findCss("a[rel=\"next\"]");
		}
		// click view detail
		// clickButtonXpath(".//*[@id='watches']/div[1]/div");
		// driver.close();
	}

	// @Test
	public void watchFinder() throws InterruptedException {
		// click price finder tab
		clickButtonXpath(".//*[@id='myNavbar']/ul[1]/li[3]/a");
		// searching
		findXpath(".//*[@id='search-watch']").sendKeys("rolex");
		clickButtonXpath(".//*[@id='button-search']");
		Thread.sleep(5000);
		// paging
		List<WebElement> listPaging = driver.findElements(By.cssSelector(".row.first_step_pagination li"));
		// for(int i = 0; i < listPaging.size() - 3; i++)
		// {//have problem can not click
		// clickButtonCss(".row.first_step_pagination .boxpaging-search li:last-child
		// a");
		// Thread.sleep(7000);
		// }
		// click view detail
		clickButtonXpath(".//*[@id='watches']/div[1]/div");
		Thread.sleep(2000);
		// check URL consist of 'review-specifications-quote'
		checkConsistOFQuoteString();

	}

	// @Test
	public void comPare() throws InterruptedException {

		// add product to compare
		this.driver.get("https://askme.watch/watch/detail/1");
		Thread.sleep(5000);
		// click compare bt //*[@id="compare-prc"]
		clickButtonCss("button#compare-prc");
		Thread.sleep(3000);
		// accept pop up
		acceptAlertMessage();
		Thread.sleep(5000);

		// driver.get("https://askme.watch/watch/detail/2");
		this.driver.navigate().to("https://askme.watch/watch/detail/2");
		Thread.sleep(5000);
		WebElement compareBtnElm = findCss("button#compare-prc");
		if (!clickButtonCss(compareBtnElm)) {
			scrollElementIntroView(compareBtnElm, -100);
			clickButtonCss(compareBtnElm);
		}
		Thread.sleep(5000);
		// accept pop up
		acceptAlertMessage();
		Thread.sleep(5000);
		// click watch to compare
		clickButtonXpath("html/body/div[2]/div[4]/p");
		clickButtonXpath(".//*[@id='compare']");
		Thread.sleep(3000);

	}

	@Test
	public void addToMyWishlist() throws InterruptedException {

		logInFaceBook();
		// add product to my wishlist
		driver.get(
				"https://askme.watch/watch/detail/33?Search=A.-LANGE-&-SOHNE-LANGE-1-LANGE-1-38,5MM-191021-31000-review-specifications-quote");
		Thread.sleep(2000);
		clickButtonCss("#wishlist");

		driver.get(
				"https://askme.watch/watch/detail/1?Search=A.-LANGE-&-SOHNE-LANGE-1-LANGE-1-38,5MM-101021-31000-review-specifications-quote");
		Thread.sleep(2000);
		clickButtonCss("#wishlist");
		// open my wishlist
		driver.get("https://askme.watch/usercp/wishlist");
		Thread.sleep(2000);
		clickButtonCss(".btn-link");
		
		// share on facebook-<bug
		//Focus on new Tab: https://stackoverflow.com/questions/39449524/how-to-focus-on-second-tab-and-work-on-it-using-selenium-webdriver
		Thread.sleep(2000);
		Set<String> handles = driver.getWindowHandles();
		String currentHandle = driver.getWindowHandle();
		for (String handle : handles) {

			if (!handle.equals(currentHandle)) {
				driver.switchTo().window(handle);
			}
		}
		Thread.sleep(500);
		findCss("[name='xhpc_message_text']").sendKeys("my watch");
		clickButtonCss("#u_0_1w");
		Thread.sleep(500);
		driver.switchTo().window(currentHandle);

	}

	// @Test
	public void logInFaceBook() throws InterruptedException {
		driver.get("https://askme.watch/login");
		// log in wtih FB
		Thread.sleep(2000);
		clickButtonCss(".face");
		Thread.sleep(3000);
		// input email&pass
		findCss("#email").sendKeys("nhatthuysynova@gmail.com");
		findCss("#pass").sendKeys("Cud0123456789");
		clickButtonCss("#loginbutton");

	}

	@After
	public void name() throws InterruptedException {
		Thread.sleep(30000);
		this.driver.close();
	}

	public void scrollElementIntroView(WebElement element, int padding) {
		JavascriptExecutor jse = (JavascriptExecutor) this.driver;
		jse.executeScript("arguments[0].scrollIntoView(true);window.scrollBy(0," + padding + ");", element);
	}

	public Boolean clickButtonXpath(String idButton) {
		try {
			WebElement itemElement = this.driver.findElement(By.xpath((idButton)));
			itemElement.click();
			Thread.sleep(200);
			return true;
		} catch (Exception ex) {
			System.out.println("Not found for click button:" + idButton + ":" + ex.getMessage());
			return false;
		}
	}

	public Boolean clickButtonCss(String cssSelector) {
		try {

			WebElement itemElement = this.driver.findElement(By.cssSelector((cssSelector)));
			itemElement.click();
			Thread.sleep(200);
			return true;
		} catch (Exception ex) {
			System.out.println("Not found element to click:" + cssSelector + ":" + ex.getMessage());
			return false;
		}
	}

	public Boolean clickButtonCss(WebElement itemElement) {
		try {
			itemElement.click();
			Thread.sleep(200);
			return true;
		} catch (Exception ex) {
			System.out.println(
					"Can not click on button:" + itemElement.getAttribute("innerHTML") + ":" + ex.getMessage());
			return false;
		}
	}

	public WebElement findXpath(String idButton) throws InterruptedException {
		try {
			WebElement itemElement = this.driver.findElement(By.xpath(idButton));
			return itemElement;
		} catch (Exception ex) {
			System.out.println("Not found for find button:" + idButton);

			return null;
		}
	}

	public WebElement findCss(String idButton) throws InterruptedException {
		try {
			WebElement itemElement = this.driver.findElement(By.cssSelector(idButton));
			return itemElement;
		} catch (Exception ex) {
			System.out.println("Not found for find button:" + idButton + ";" + ex.getMessage());
			// System.exit(0);
			return null;
		}
	}

	public void waitForElementAppearCSS(String s) {
		WebDriverWait wait = new WebDriverWait(driver, 15);
		wait.until(ExpectedConditions.visibilityOfElementLocated(By.cssSelector(s)));
	}

	public void waitForElementAppearXpath(String s) {
		WebDriverWait wait = new WebDriverWait(driver, 15);
		wait.until(ExpectedConditions.visibilityOfElementLocated(By.xpath(s)));
	}

	public Boolean equalTwoString(String s1, String s2) {
		if (s1.equals(s2)) {
			return true;
		} else {
			System.out.println("String do NOT equal:" + s1 + "\n" + s2);
			return false;
		}
	}

	public void checkConsistOFQuoteString() {
		String s = driver.getCurrentUrl().trim();
		// get 'review-specification-quote' of URL
		String lastCharOfUrl = s.substring(s.length() - 27, s.length());
		// compare two String
		if (!lastCharOfUrl.equals("review-specifications-quote")) {
			System.out.println("URL do not consist of 'review-specifications-quote'" + "\n" + lastCharOfUrl);
		} else {
			System.out.println("Url consist of 'review-specifications-quote'");
		}
	}

	public boolean acceptAlertMessage() throws InterruptedException {

		try {
			Alert alertMessage = driver.switchTo().alert();
			alertMessage.accept();
			Thread.sleep(400);
			driver.switchTo().defaultContent();
			return true;
		} catch (NoAlertPresentException Ex) {
			Thread.sleep(400);
			return false;
		}

	}

}