Java null pointer exception in REST API

I am actually using postman to send login request to my REST API but it's giving me a javaNullpointer exception. It's because in model class one of my variables is not getting a value. setPhone_Number() function is not called in my model class. So the phone_number variable is empty.

javaNullpointer

setPhone_Number()

phone_number

Help is appreciated.

Here is my error screnshot eclipse error for null pointer
here is what i am sending through postman Postman

here is the login dao class.

public class LoginDao {

private String password;
private String phone_number;


public LoginDao(){
phone_number = null;
password = null;
}

public Response doLogin(login logg, String user_type) throws SQLException{
ResultSet rs = null;
boolean userType = true;
//if userType is resource then boolean is false, if userType is user then boolean is true.
//logg.setPhone_Number(phone_number);

DBConnection dbConnection = new DBConnection();
//Connection connection = dbConnection.getConnection();
this.phone_number = logg.getPhone_Number();
this.password = logg.getPassword();


try{
if(user_type.equalsIgnoreCase("Rider")) {
rs = dbConnection.runSql("select rider_id, phone_number, password from rider");
userType = true;

}
else if(user_type.equalsIgnoreCase("Driver")) {
rs = dbConnection.runSql("select driver_id, phone_number, password from driver");
userType = false;
}

while(rs.next()){
System.out.println(phone_number);
System.out.println(rs.getString("phone_number"));
System.out.println("user"+user_type);

if((this.phone_number.equals(rs.getString("phone_number"))) && (this.password.equals(rs.getString("password")))){


Here is model class login

public class login {

private String phone_number;
private String password;

public login(){

}

public String getPhone_Number() {

System.out.println("getting "+phone_number);
return phone_number;
}

public void setPhone_Number(String phone_number) {

System.out.println("seting "+phone_number);
this.phone_number = phone_number;
}

public String getPassword() {
return password;
}

public void setPassword(String password) {

System.out.println("seting "+password);
this.password = password;
}


}

Here is loginResource.java

import javax.ws.rs.POST;

import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

import static javax.ws.rs.core.MediaType.APPLICATION_JSON;

import java.sql.SQLException;

import javax.ws.rs.Consumes;

import io.github.yasirfaisal21.schoolvan.schoolvan.dao.LoginDao;
import io.github.yasirfaisal21.schoolvan.schoolvan.model.login;

@Path("login")


public class loginResource {
@Produces(MediaType.APPLICATION_JSON)
@Consumes(APPLICATION_JSON)
@POST
public Response doLogin(login log,@QueryParam("user_type") String user_type )
throws SQLException{


LoginDao loginDao = new LoginDao();
if(user_type.equalsIgnoreCase("Rider"))
return loginDao.doLogin(log,"Rider");
else
return loginDao.doLogin(log,"Driver");
}

}


line number 52 in LoginDao

login log

loginResource.doLogin

login

phonenumber

LoginDao

phonenumber

login

loginResource

2 Answers
2

In your login.java class, replace:

private String phone_number;
with
private String phoneNumber;


and update its getters and setters according like so:

login.java

private String phone_number;

private String phoneNumber;

public String getPhoneNumber() {
return phoneNumber;
}

public void setPhoneNumber(String phoneNumber) {
this.phoneNumber = phoneNumber;
}


In loginResource.java, the line

loginResource.java

LoginDao loginDao = new LoginDao();

LoginDao loginDao = new LoginDao();

calls this method in LoginDao:

LoginDao

public LoginDao(){
phone_number = null;
password = null;
}


where you have explicitly set phone_number = null

phone_number = null

now on Line 52 of LoginDao

LoginDao

if((this.phone_number.equals(rs.getString("phone_number"))) && (this.password.equals(rs.getString("password"))))


this.phone_number corresponds to the LoginDao object most recently constructed, which has phone_number set to null. Even before values can be compared with rs, the equals function fails and you get a null pointer exception.

this.phone_number

LoginDao

phone_number

rs

equals

null pointer

You should instead take in the values phone_number and password from the request. Try creating a parametrized constructor and assigning them the values you pass, like so:

phone_number

password

public LoginDao(String number, String password){
this.phone_number = number;
this.password = password;
}


and calling it from loginResource like so:

loginResource

if(user_type.equalsIgnoreCase("Rider"))
return new loginDao(number,password).doLogin(log,"Rider");
else
return new loginDao(number,password).doLogin(log,"Driver");
}


Alternatively, I think you are trying to save parameters into Login object, but you haven't done that anywhere in loginResource. You should change your constructor in loginDao to

Login

loginResource

loginDao

public loginDao() { }


and write the following in loginResource :

loginResource

Login login = new Login();
if(user_type.equalsIgnoreCase("Rider")){
login.setPhone_number("your phone number from request");
return loginDao.doLogin(log,"Rider");
}
else
{
login.setPhone_number("your phone number from request");
return loginDao.doLogin(log,"Driver");
}


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