新手上路，求助大神selenium webdriver 火狐，IE，Chrome并发报空指针错误

[qq_29077265]

package FirstNGDemo;

import org.testng.annotations.Test;
import org.testng.annotations.BeforeMethod;
import org.testng.annotations.Parameters;
import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.ie.InternetExplorerDriver;
import org.testng.Assert;
import org.testng.annotations.AfterMethod;

public class MultipleBrowseSearchTest {
public WebDriver driver;
String baseUrl = "http://www.sogou.com"; //设定访问网站的地址

@Parameters("browser")

@BeforeMethod
public void beforeMethod(String Browser) {
if(Browser.equalsIgnoreCase("firefox")) {
System.setProperty("webdriver.firefox.bin", "C:\\program Files (x86)\\Mozilla Firefox\\firefox.exe");
driver = new FirefoxDriver();
}else if(Browser.equalsIgnoreCase("ie")) {
System.setProperty("WebDriver.ie.driver", "D:\\IEDriverServer.exe");
driver = new InternetExplorerDriver();
}
else {
System.setProperty("webdriver.chrome.driver","D:\\chromedriver.exe");
driver = new ChromeDriver();
}
}
@Test
public void TestSearch() {
//打开Sogou首页
driver.get("http://www.sogou.com");
//在搜索框中输入“12306"
WebElement inputBox = driver.findElement(By.id("query"));
Assert.assertTrue(inputBox.isDisplayed());
inputBox.sendKeys("12306");
//单击“搜索”按钮
driver.findElement(By.id("stb")).click();
//单击“搜索”按钮后等待3秒，让 页面完成显示过程
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//判断搜索结果的页面是否包含测试数据中期待的关键字
Assert.assertTrue(driver.getPageSource().contains("123"));
}


@AfterMethod
public void afterMethod() {
driver.quit();
}

}

运行时只能运行Chrome浏览器，火狐和IE都启动不了，注释了Chrome浏览器的代码，就报了空指针
[RemoteTestNG] detected TestNG version 6.8.2
[TestNG] Running:
C:\Users\Administrator\AppData\Local\Temp\testng-eclipse-1741731778\testng-customsuite.xml

FAILED CONFIGURATION: @AfterMethod afterMethod
java.lang.NullPointerException
at FirstNGDemo.MultipleBrowseSearchTest.afterMethod(MultipleBrowseSearchTest.java:59)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:84)
at org.testng.internal.Invoker.invokeConfigurationMethod(Invoker.java:564)
at org.testng.internal.Invoker.invokeConfigurations(Invoker.java:213)
at org.testng.internal.Invoker.invokeMethod(Invoker.java:786)
at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:901)
at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1231)
at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:127)
at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:111)
at org.testng.TestRunner.privateRun(TestRunner.java:767)
at org.testng.TestRunner.run(TestRunner.java:617)
at org.testng.SuiteRunner.runTest(SuiteRunner.java:334)
at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:329)
at org.testng.SuiteRunner.privateRun(SuiteRunner.java:291)
at org.testng.SuiteRunner.run(SuiteRunner.java:240)
at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:86)
at org.testng.TestNG.runSuitesSequentially(TestNG.java:1224)
at org.testng.TestNG.runSuitesLocally(TestNG.java:1149)
at org.testng.TestNG.run(TestNG.java:1057)
at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:114)
at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:251)
at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:77)

FAILED: TestSearch
java.lang.NullPointerException
at FirstNGDemo.MultipleBrowseSearchTest.TestSearch(MultipleBrowseSearchTest.java:38)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:84)
at org.testng.internal.Invoker.invokeMethod(Invoker.java:714)
at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:901)
at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1231)
at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:127)
at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:111)
at org.testng.TestRunner.privateRun(TestRunner.java:767)
at org.testng.TestRunner.run(TestRunner.java:617)
at org.testng.SuiteRunner.runTest(SuiteRunner.java:334)
at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:329)
at org.testng.SuiteRunner.privateRun(SuiteRunner.java:291)
at org.testng.SuiteRunner.run(SuiteRunner.java:240)
at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:86)
at org.testng.TestNG.runSuitesSequentially(TestNG.java:1224)
at org.testng.TestNG.runSuitesLocally(TestNG.java:1149)
at org.testng.TestNG.run(TestNG.java:1057)
at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:114)
at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:251)
at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:77)


===============================================
Default test
Tests run: 1, Failures: 1, Skips: 0
Configuration Failures: 1, Skips: 0
===============================================


===============================================
Default suite
Total tests run: 1, Failures: 1, Skips: 0
Configuration Failures: 1, Skips: 0
===============================================

[TestNG] Time taken by org.testng.reporters.EmailableReporter2@4411d970: 15 ms
[TestNG] Time taken by org.testng.reporters.SuiteHTMLReporter@3f3afe78: 25 ms
[TestNG] Time taken by [FailedReporter passed=0 failed=0 skipped=0]: 7 ms
[TestNG] Time taken by org.testng.reporters.JUnitReportReporter@7f690630: 5 ms
[TestNG] Time taken by org.testng.reporters.XMLReporter@2d6e8792: 9 ms
[TestNG] Time taken by org.testng.reporters.jq.Main@511baa65: 45 ms