NullPointerException on validating email

Question

I am writing a unit test to check the email validation logic. The logic is throwing null pointer exception when you run the test. But it works fine with emulator. Can someone help me solving this?

public static String validate(String email, String password) {
        if (email == null || email.isEmpty() || !android.util.Patterns.EMAIL_ADDRESS.matcher(email).matches()) {
            return "Enter valid email address";
        }
        if (password.isEmpty() || password.length() < 4) {
            return "Password should be between 4 and 10 alphanumeric characters";
        }
        return null;
}

Below is my unit test.

@Test
public void validateShouldReturnMessageIfYouPassAnInvalidEmail() throws Exception {
    String validateMessage = LoginService.validate("abcdef", "password");
    assertEquals("Enter valid email address", validateMessage);
}

The error I am getting is,

java.lang.NullPointerException
at com.tryout.hemanth.expensetracker.service.LoginService.validate(LoginService.java:11)

@ShreeKrishna i have a validate method which does the validation. As I have added my login in question. — Hemanth S R, May 18 '16 at 14:39
If that's the line where you get the NPE, it looks like `android.util.Patterns.EMAIL_ADDRESS` is `null`. — Axel, May 18 '16 at 14:43
have you tried using regex or removing that line ? and is it working well ? — Shree Krishna, May 18 '16 at 14:52
@ShreeKrishna without android.util.Patterns.EMAIL_ADDRESS.matcher(email).matches() it works fine — Hemanth S R, May 18 '16 at 14:56
Do you have API Level 8 available when running JUnit? To be honest, I don't know how JUnit integrates with your Android build environment, so this is just a guess... — Axel, May 18 '16 at 15:02
@HemanthGowda yah ok then.. I added an answer in detail with a link. Hope you will find that helpful It should be working. — Shree Krishna, May 18 '16 at 15:07
@Axel But the same code works fine with emulator. I don't know why android is null when i run it through Junit. — Hemanth S R, May 18 '16 at 15:08

score 24 · Answer 1 · answered Sep 16 '19 at 09:59

24

Use PatternsCompat instead of Patterns

answered Sep 16 '19 at 09:59

Anjula

1,690
23
29

Why PatternsCompat works? The pattern's string is the same – Massimo Jan 29 '21 at 09:54
1

Interesting `PatternsCompat` belongs in `androidx` which is newer – cutiko Feb 24 '22 at 14:49
1

`PatternsCompat` made my day – Mohd Qasim Mar 17 '22 at 11:28

Shree Krishna · Accepted Answer · 2020-08-17T06:26:01.197

2

android.util.Patterns.EMAIL_ADDRESS.matcher(email).matches() exists since API level 8, May be your emulator is prior than this.

So I suggest Adding custom EMAIL_ADDRESS_PATTERN string as suggested in this answer and check it like

if (email == null || email.isEmpty() || !EMAIL_ADDRESS_PATTERN.matcher(email).matches()){
     return "Enter valid email address";
}

edited Aug 17 '20 at 06:26

answered May 18 '16 at 15:02

Shree Krishna

8,474
6
40
68

But the same code works fine with emulator. I don't know why android is null when i run it through Junit. – Hemanth S R May 18 '16 at 15:08
Are you sure you are using JUNIT latest like 4. Or your device's API level is compatible ? [see](https://developer.android.com/topic/libraries/testing-support-library/index.html#ajur-junit) the requirements and rules of testing. – Shree Krishna May 18 '16 at 15:14
This issue is not because of emulator but the android sdk version. In my case Patterns.EMAIL_ADDRESS works as expected below version 28 but it suddenly returns null on version 29. – Amey Bhandarkar Aug 13 '20 at 09:22

Necromancer · Answer 3 · 2022-05-18T08:31:40.753

1

In case if Patterns.EMAIL_ADDRESS doesn't match with your requirements,

create your own regex pattern for better use.

Please refer to this EMAIL ADDRESS regex for instance.

edited May 18 '22 at 08:31

answered May 18 '16 at 15:43

Necromancer

869
2
9
25

Because the regex is complex does't mean it is not right. What if you have to validate an email your simpler regex does not cover? – Kaizie Apr 09 '18 at 14:16
@Kaizie Yes you are right. I mean you can customize you validation as you want. Complex or simple is based on you business logic – Necromancer May 19 '18 at 06:17

score 0 · Answer 4 · answered May 07 '22 at 18:39

try this, this is working for me :

fun isValidEmail(email:String?):Boolean {
return when{
    email.isNullOrEmpty()-> false
    else-> PatternsCompat.EMAIL_ADDRESS.matcher(email).matches();
}

}

Test cases:

 @Test
fun validate_email_invalid() {
    val email = "a"
    Assert.assertEquals(false, isValidEmail(email))
}

NullPointerException on validating email

4 Answers4