Danilo Congradac :
I have a problem with my spring boot web application. I have MainContorller class and CheckerClass. It says, in the end, it is java.lang.NullPointerexception, but I am not sure what to do with that information.
MainController class:
package danilocongradac.webApp;
import javax.servlet.http.HttpServletRequest;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
@Controller
public class MainController {
private static CheckerClass checker = new CheckerClass();
@GetMapping(value = {"/", "/home"})
public static String mainPage() {
return "index";
}
@GetMapping(value = {"/error"})
public static String errorPage() {
return "error";
}
@GetMapping(value = {"/signIn"})
public static String inputPage() {
return "signIn";
}
@GetMapping(value = {"output"})
public static String outputPage(){
return "output";
}
@RequestMapping(value = {"/inputCheck"})
public static String inputPageCheck(HttpServletRequest req,Model m){
String email = req.getParameter("email");
String password = req.getParameter("password");
System.out.println("email: " + email);
System.out.println("password: " + password);
// checker
if(checker.check(email, password))
return "output";
return "input";
}
}
And CheckerClass:
package danilocongradac.webApp;
import java.util.ArrayList;
public class CheckerClass {
private static ArrayList<User> users;
public CheckerClass(){
users.add(new User("danilo", "congradac", "[email protected]", "danilo2002"));
}
public void addUser(String name, String surname, String email, String password){
users.add(new User(name, surname, email, password));
}
public boolean check(String email, String password) {
users.add(new User("danilo", "congradac", "[email protected]", "danilo2002"));
for(User u : users) {
if(email.equals(u.getEmail()) && password.equals(u.getPassword()))
return true;
}
return false;
}
}
And I get error message like this... Error message is below:
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'mainController' defined in file [/home/danilocongradac/Documents/java/webApp/target/classes/danilocongradac/webApp/MainController.class]: Instantiation of bean failed; nested exception is java.lang.ExceptionInInitializerError
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1320) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1214) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:879) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:878) ~[spring-context-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) [spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
at danilocongradac.webApp.App.main(App.java:12) [classes/:na]
Caused by: java.lang.ExceptionInInitializerError: null
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_242]
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_242]
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_242]
at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_242]
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:200) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:87) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1312) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
... 17 common frames omitted
Caused by: java.lang.NullPointerException: null at danilocongradac.webApp.CheckerClass.<init>(CheckerClass.java:9) [classes/:na] at danilocongradac.webApp.MainController.<clinit>(MainController.java:12) ~[classes/:na]
... 24 common frames omitted
Rahul Agrawal :
In the CheckerClass class users variable is not initialized. In constructors initialise it before using it.
public CheckerClass(){
users= new ArrayList<User>();
users.add(new User("danilo", "congradac", "[email protected]", "danilo2002"));
}
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