Module 9 -TestNG -- DataProvider Anotation

Hi Please help me to solve this problem.
Test "[b:34pwe29z]yahooRegistrationTest.java[/b:34pwe29z]" file with"[b:34pwe29z]DataProvider[/b:34pwe29z]" Annotation. After run individual or run with [b:34pwe29z]testng.xml [/b:34pwe29z]file it display below error message so please suggest me where i am wrong.

NOTE:- Project attached with screenshot.
[b:34pwe29z]NOTE:- Waiting for you reply.[/b:34pwe29z]

Code:-

package test;

import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;

public class yahooRegistrationTest {

@Test(dataProvider="registerData")
public void testRegister(String username,String password,String email, String city){

System.out.println(username +"---"+ password +"---"+ email +"---"+ city );

}

@DataProvider
public Object[][] registerData(){

Object [][] data = new Object[2][4];

data[0][0] = "sumit";
data[0][1] = "sumit1123";
data[0][2] = "sumit1123@gmail.com";
data[0][3] = "Delhi";

data[1][0] = "sumit";
data[1][1] = "sumit1123";
data[1][2] = "sumit1123@gmail.com";
data[1][3] = "Delhi";

return data;
}

}