Why am I getting NullPointerException in my tests?

Question

My test suite is organized into two parts: a library of test data, xpath locations for WebElements, .click() commands, etc. I also have a test suite.

This is an example test that shares the package it deals with for experimentation purposes. As of right this second I'm not worried about outputting results (I know how to do that), the code simply needs to work.

package LoginPage;

import org.openqa.selenium.firefox.FirefoxDriver;
import java.util.concurrent.TimeUnit;
import org.junit.*;
import org.openqa.selenium.*;

public class FunctionCheck {
      private WebDriver driver;
      private String baseUrl;

      @Before
      public void setUp() throws Exception {
        driver = new FirefoxDriver();
        baseUrl = "http://www.XXXXXXXXXXX.com/";
        driver.manage().timeouts().implicitlyWait(30, TimeUnit.SECONDS);
      }
      @Test
      public void test() throws Exception {
        driver.get(baseUrl + "XXXXXXXXXXXX");
        Thread.sleep(600);
        LoginPage.enterValidCredentials myins = new LoginPage.enterValidCredentials();
        myins.run();
      }
      @After
      public void tearDown() throws Exception {
        driver.quit();
      }
}

This is the class "enterValidCredentials" that sits in the same package.

package LoginPage;

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;

public class enterValidCredentials { // This class enters in a valid username and valid password on the login page.
    public void run() {
        WebDriver driver;
        driver.findElement(By.cssSelector("input[type=\"text\"]")).sendKeys("XXXXXX");
        driver.findElement(By.cssSelector("input[type=\"password\"]")).sendKeys("XXXXXX");    
    }
}

I got two problems:

In the class "enterValidCredentials", it wants me to "initialize" the driver variable. The autofix for this in Eclipse sets line 8 to WebDriver driver = null;.
Doing the above has my test throw a NullPointerException.

I've been searching through documentation for a while now. I'm really stumped as to what is going on. All I want is the run() method to literally run, and plug in the info to the page. That's the goal.

You need to initialize driver like you do in your setUp() method with the new keyword. — yogidilip, Oct 07 '15 at 14:20
Please use Java naming conventions: packages have lowercase names, classes have UpperCamelCaseNames. — Andy Turner, Oct 07 '15 at 14:21
Until you know enough to *evaluate* Eclipse's suggested corrections, you would be well advised to ignore them. You could even consider turning them off. Throwing in random code that happens to make a compilation error go away will not help you learn, and will not reliably make your programs work. — John Bollinger, Oct 07 '15 at 14:26
@AndyTurner Wouldn't classes be namedLikeThis? I was under the impression it was always lowercaseCapital. — jagdpanzer, Oct 07 '15 at 14:34
A quick look at the Java API should tell you not: PrintWriter, BufferedInputStream, ProcessBuilder etc. But here is Sun's page on the matter: http://www.oracle.com/technetwork/java/codeconventions-135099.html — Andy Turner, Oct 07 '15 at 14:35
Possible duplicate of [What is a Null Pointer Exception, and how do I fix it?](http://stackoverflow.com/questions/218384/what-is-a-null-pointer-exception-and-how-do-i-fix-it) — Louis, Oct 07 '15 at 16:19

score 2 · Accepted Answer · answered Oct 07 '15 at 14:17

2

public class enterValidCredentials {
  public void run(WebDriver driver) {
    driver.findElement(By.cssSelector("input[type=\"text\"]")).sendKeys("XXXXXX");
    driver.findElement(By.cssSelector("input[type=\"password\"]")).sendKeys("XXXXXX");    
  }
}

Pass your existing WebDriver instance into enterValidCredentials.run:

myins.run(driver);

answered Oct 07 '15 at 14:17

Andy Turner

137,514
11
162
243

Worked perfectly, thanks man! I'm a Perl guy personally but my job requires Java so I'm still making simple mistakes like this. I appreciate it! – jagdpanzer Oct 07 '15 at 14:33

score 1 · Answer 2 · answered Oct 07 '15 at 14:17

Here is your problem. driver is uninitialized. Because it is a local variable, the compiler will require you to initialize it. And when, as you said, you initialize it to null, the 2 following lines dereference it. You cannot call a method on a object that points to nothing.

            WebDriver driver;
            driver.findElement(By.cssSelector("input[type=\"text\"]")).sendKeys("XXXXXX");
            driver.findElement(By.cssSelector("input[type=\"password\"]")).sendKeys("XXXXXX");

You must assign it a value

WebDriver driver = ...some object reference...;

score 1 · Answer 3 · answered Oct 07 '15 at 14:22

1

Try to initialize your driver like

private WebDriver driver=new FirefoxDriver();

Mate, better use debug )

answered Oct 07 '15 at 14:22

Shell Scott

1,679
18
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Why am I getting NullPointerException in my tests?

3 Answers3