java代码如下：
package com.mushishi.Imooc;

import org.testng.annotations.Test;

import org.testng.annotations.BeforeMethod;
import org.testng.annotations.AfterMethod;
import org.testng.annotations.BeforeClass;

import java.util.ArrayList;
import java.util.List;

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.chrome.ChromeDriver;
import org.testng.annotations.AfterClass;
import org.testng.annotations.BeforeTest;
import org.testng.annotations.AfterTest;

public class ShopsCaseTestng {

public WebDriver driver;



public ArrayList<String> getShopTitles() {
	List<WebElement> titleElements = driver.findElements(By.className("shizan-name"));
	ArrayList<String> shopTitles = new ArrayList<String>();
	for(WebElement element : titleElements) {
		String shopTitle = element.getAttribute("innerHTML");
		shopTitles.add(shopTitle);
	}
	return shopTitles;
}


public void initDriver() {
	driver = new ChromeDriver();
	driver.get("https://www.imooc.com/");
	try {
		Thread.sleep(3000);
	} catch (InterruptedException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
	driver.manage().window().maximize();
	try {
		Thread.sleep(2000);
	} catch (InterruptedException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
	driver.findElement(By.linkText("实战课程")).click();
	try {
		Thread.sleep(5000);
	} catch (InterruptedException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
	
	

}

/*
@Test
public void f() {
ArrayList titles = getShopTitles();
for(int i = 0;i<titles.size();i++) {
String title = titles.get(i);
WebElement shopElement = driver.findElement(By.xpath("//p[@title=’"+title+"’]"));
shopElement.click();
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
driver.navigate().back();
}

}
**/

@Test
public void test1() {
	List<WebElement> titleElements = driver.findElements(By.className("shizan-name"));
	for(WebElement element : titleElements) {
		System.out.println(element.getText());
		element.click();
		driver.navigate().back();
		try {
			Thread.sleep(3000);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		titleElements = driver.findElements(By.className("shizan-name"));
	}
	
}

@BeforeMethod
public void beforeMethod() {
}

@AfterMethod
public void afterMethod() {
}

@BeforeClass
public void beforeClass() {
initDriver();
}

@AfterClass
public void afterClass() {

// driver.close();
}

@BeforeTest
public void beforeTest() {
}

@AfterTest
public void afterTest() {
}

}

老师，请问我是按照视频中的方法，两次获取list，但是结果为啥还是一样报错呢？