Spring Data. Delete child entity on deleting one of the parents

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• recursion method not returning a string

  I have to create a code that can find the longest palindrome contained inside sentences. (eg. Some people like cake but I prefer pie; the longest palindrome is i prefer pi). The problem is that upon running the code it doesn't return the palindrome. I'm not sure what the problem is but if anyone can figure it out I'd appreciate you letting me know. Thanks!

  Code is below...

  public class Recursion6 {
      
      static String recursion(String word, int currentLength, int x, String substring) {
          String reverse =new StringBuffer(word).reverse().toString();
          if(word.length() == 1 ){
              return substring;
          }
          if(word.charAt(0) != word.charAt(x)) {
              if(x == word.length() - 1) {
                  recursion(word.substring(1), currentLength, 1, substring);
              }
              x++;
              recursion(word, currentLength, x, substring);
          } else {
              if(word.substring(0, x + 1).equalsIgnoreCase(reverse.substring(word.length() - (x+1), word.length()))) {
                  if(word.substring(0, x).length() > currentLength) {
                      currentLength = word.substring(0, x + 1).length();
                      substring = word.substring(0, x + 1);
                      
                  }
                  recursion(word.substring(1), currentLength, 1, substring);
              }
              recursion(word.substring(1), currentLength, 1, substring);
          }
          return substring;
      }
      
  
      public static void main(String[] args){
          Scanner sc=new Scanner(System.in);
      System.out.println("Enter a Sentence:");
      String word=sc.nextLine();
          System.out.println("The Palendrome is "+recursion(word.replaceAll(" ", ""), 1, 1, null));        
      sc.close();
      }
  }
  
• Groovy v3.0.7 doesn't support static interface methods

  I have created a simple example groovy script under groovy v3.0.7, and Java 11.0.5

  interface IFace {
      static  String sMethod () {
          return "hello"
      }
  }
  
  class Test implements IFace {
  
  }
  
  IFace i = new Test()
  
  println i.sMethod()
  

  however the parrot parser won't except this. If you run this you gives the following error

  org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
  ideaGroovyConsole.groovy: 2: The method 'java.lang.String sMethod()' from interface 'IFace' must not be static. Only fields may be static in an interface.
   @ line 2, column 5.
         static  String sMethod () {
         ^
  
  1 error
  

  Why doesn't the latest 3.0.7 build support static interface methods. Have I missed something ?
• HTTP Post method not supported by this URL when deployed to jboss EAP 7.1

  I've a REST API, that is deployed on JBoss EAP 7.1. When I hit the URL at

  http://localhost:8080/MyApp/group
  

  in postman, it gives "HTTP method POST is not supported by this URL" error with status code 405.

  When I deploy this API on embedded tomcat server, it works perfectly fine. Here is my controller

  @RestController
  public class RequestController {
      
      @Autowired
      private GroupService groupService;
      
      @PostMapping( "/group" )
      public GroupInfo fetchGroupInfo( @RequestBody GroupInfo groupInfo ) {
          
          long groupId = groupInfo.getGroupId();
          return groupService.getGroup( groupId );
          
      }
  
  }
  

  main class

  @SpringBootApplication
  public class MyApp extends SpringBootServletInitializer {
  
      /**
       * @param args
       */
      public static void main(String[] args) {
          SpringApplication.run(MyApp.class, args);
      }
      
      @Override
      protected SpringApplicationBuilder configure(SpringApplicationBuilder builder){
          return builder.sources(MyApp.class);
      }
      
  }
  

  pom.xml

  <project xmlns="http://maven.apache.org/POM/4.0.0"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
      <modelVersion>4.0.0</modelVersion>
      <groupId>com.my.package</groupId>
      <artifactId>MyApp</artifactId>
      <version>0.0.1-SNAPSHOT</version>
      <name>MyApp</name>
      <packaging>war</packaging>
      
      <properties>
          <java.version>1.8</java.version>
      </properties>
  
      <parent>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-parent</artifactId>
          <version>1.5.4.RELEASE</version>
      </parent>
  
      <dependencies>
          <dependency>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter-web</artifactId>
          </dependency>
          <dependency>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter-tomcat</artifactId>
              <scope>provided</scope>
          </dependency>
          <dependency>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter-data-jpa</artifactId>
          </dependency>
          
      </dependencies>
      
      <build>
          <finalName>MyApp</finalName>
          <plugins>
              <plugin>
                  <groupId>org.springframework.boot</groupId>
                  <artifactId>spring-boot-maven-plugin</artifactId>
              </plugin>
          </plugins>
      </build>
  
  </project>
  

  The deployment shows no error messages. However, it does show below warning

   WARN  [org.jboss.weld.deployer] (MSC service thread 1-4) WFLYWELD0013: Deployment optumRx-0.0.1-SNAPSHOT.war contains CDI annotations but no bean archive was found (no beans.xml or class with bean defining annotations was present).
  

  And the class files are missing in the deployment folder in jboss. Can you please tell, what am I missing?
• @Valid Not working @PostMapping spring boot

  I am learning spring boot, I am adding Validation for @PostMapping, but somehow it always create a object even with non-valid value.

  Hospital.java

  public class Hospital {
      private Integer id;
      @Size(min = 2)
      private String name;
      @Size(min = 2)
      private String city;
  
      public Hospital(Integer id, String name, String city) {
          this.id = id;
          this.name = name;
          this.city = city;
      }
  

  Controller

  @Autowired
      HospitalData data;
  ...
  @PostMapping("/hospital")
      public ResponseEntity<Hospital> addHospital(@Valid @RequestBody Hospital hospital){
          Hospital newHospital = data.addHospital(hospital);
  
          URI location = ServletUriComponentsBuilder
          .fromCurrentRequest()
          .path("/{id}")
          .buildAndExpand(newHospital.getId()).toUri();
  
          return ResponseEntity.created(location).build();
      }
  

  pom.xml

  <dependency>
              <groupId>javax.validation</groupId>
              <artifactId>validation-api</artifactId>
          </dependency>
  

  And previously I have added below dependency as I am using Spring 2.3.10 RELEASE, but it doesn't work, so I have added above dependency.

  <dependency>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter-validation</artifactId>
          </dependency>
  
• Java Spring : how can I encapsulate annotations within an other annotation?

  Is it possible to encapsulate an annotation within an other annotation with values?

  I have a lot of end points on my API and would like to automate the required roles / permissions for the end point access.

  Here is the current code :

  @RestController
  @RequestMapping("/health")
  public class HealthController {
      @GetMapping("/isAlive")
      @PreAuthorize("hasAnyAuthority('ISALIVE', 'HEALTH_ENDPOINT')")
      public String isAlive() {
          return "Server is up and running";
      }
  
      @GetMapping("/hello")
      @PreAuthorize("hasAnyAuthority('HELLO', 'HEALTH_ENDPOINT')")
      public String hello() {
          return "Hello";
      }
  }
  

  I have 2 authorities per end point, the first is the name of the mapping and method and the second is the name of the class.

  In this example there is only 2 different end points with makes it easy but the finished product will have in the hundreds and doing all of the authorities by hand is going to be error-prone and not very efficient.

  This is the desired result :

  @RestController
  @RequestMapping("/health")
  public class HealthController {
      @GetMapping("/isAlive")
      @MyAuthorisationAnnotation
      public String isAlive() {
          return "Server is up and running";
      }
  
      @GetMapping("/hello")
      @MyAuthorisationAnnotation
      public String hello() {
          return "Hello";
      }
  }
  

  Where @MyAuthorisationAnnotation would give the right parameters to the @PreAuthorize annotation.

  Is it possible?
• Where to Learn Java development(web development) without spring or springboot

  I started to learn java web development. So I started with Springboot. I was able to understand Springboot but not in depth, for which I started to learn some concepts of spring which definitely helped. But now I want go deeper. So my question is,

  a) Where should I learn raw Java web development as people used to do without Spring, Springboot, Hibernate and all the other tools, because without understanding this I wont ever get comfortable with Springboot or Spring. What books, video lectures or websites I should follow.

  b) Should I even do this.(Keeping in mind I actually want go in depth)
• Remote database connection with spring boot

  I have connected remote database by following below properties:

  spring.datasource.driver-class-name=com.mysql.jdbc.Driver
  spring.datasource.url=jdbc:mysql://<server-ip>:3306/db_name
  spring.datasource.username=
  spring.datasource.password=
  spring.datasource.testWhileIdle=true
  spring.datasource.validationQuery=SELECT 1
  
  spring.jpa.database=MYSQL
  spring.jpa.hibernate.naming-strategy=org.hibernate.cfg.ImprovedNamingStrategy
  spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect
  spring.jpa.hibernate.ddl-auto=validate
  spring.jpa.generate-ddl=true
  spring.jpa.show-sql=true
  

  I didn't get any error of database while building application. All crud operations are successfully done without any error while testing the application in local. But data is not updating in remote database. I didn't catch the issue. Could you please help me to solve that issue.

  Thanks in advance.
• Spring boot Unable to evaluate the expression Method threw 'org.hibernate.LazyInitializationException' exception. using getter, ManyToMany relation

  I've got two classes Participant and TimeWindow. Multiple participants can register for multiple TimeWindow, hence the ManyToMany relation

  @Entity
  @Table
  public class Participant {
      @Id
      @SequenceGenerator(
              name = "participant_sequence",
              sequenceName = "particant_sequence",
              allocationSize = 1
      )
      @GeneratedValue(
              strategy = GenerationType.SEQUENCE,
              generator = "participant_sequence"
      )
      private Long id;
      private String name;
      private String number;
      private String details;
  
      @ManyToMany(fetch = FetchType.LAZY)
      @JoinTable(name = "ParticipantCreneaux")
      private Collection<TimeWindow> registeredTimeWindow;
  
  
      public Participant() {
  
      }
      public Participant(String nom, String num, String details) {
          this.name = nom;
          this.number = num;
          this.details = details;
          this.registeredTimeWindow = new ArrayList<>();
      }
      public void addTimeWindow(TimeWindow c){
          registeredTimeWindow.add(c);
      }
      public void removeTimeWindow(TimeWindow c){
          registeredTimeWindow.remove(c);
      }
  
      public String getName() {
          return name;
      }
  
      public void setName(String name) {
          this.name = name;
      }
  
      public String getNumber() {
          return number;
      }
  
      public void setNumber(String number) {
          this.number = number;
      }
  
      public String getDetails() {
          return details;
      }
  
      public void setDetails(String details) {
          this.details = details;
      }
  
      public void setId(Long id) {
          this.id = id;
      }
  
      public Long getId() {
          return id;
      }
  
      public Collection<TimeWindow> getRegisteredTimeWindow() {
          return registeredTimeWindow;
      }
  }
  

  And the TimeWindow class:

  @Entity
  @Table
  public class TimeWindow {
      @Id
      @SequenceGenerator(
              name = "creneau_sequence",
              sequenceName = "creneau_sequence",
              allocationSize = 1
      )
      @GeneratedValue(
              strategy = GenerationType.SEQUENCE,
              generator = "creneau_sequence"
      )
      private Long id;
      private LocalTime hourStart;
      private LocalTime hourEnd;
  
      public Collection<Participant> getListParticipants() {
          return listParticipants;
      }
  
      @ManyToMany(fetch = FetchType.LAZY,cascade=CascadeType.ALL,mappedBy = "registeredTimeWindow")
      private Collection<Participant> listParticipants;
  
      public TimeWindow(LocalTime hourStart, LocalTime hourEnd) {
          this.hourStart = hourStart;
          this.hourEnd = hourEnd;
          this.listParticipants = new ArrayList<>();
      }
  
      public TimeWindow() { }
  
      public LocalTime getHourEnd() {
          return hourEnd;
      }
  
      public void setHourStart(LocalTime hourStart) {
          this.hourStart = hourStart;
      }
  
      public void setHourEnd(LocalTime hourEnd) {
          this.hourEnd = hourEnd;
      }
  
      public LocalTime getHourStart() {
          return hourStart;
      }
  
      public int getNbParticipants(){
          return listParticipants.size();
      }
      public void addParticipant(Participant participant){
          this.listParticipants.add(participant);
      }
      public void removeParticipant(Participant participant){
          this.listParticipants.remove(participant);
      }
  
      public void setId(Long id) {
          this.id = id;
      }
  
      public Long getId() {
          return id;
      }
  }
  

  Right now I'm still learning Spring boot, I haven't found anything about it so far or anything that helped me.

  The error is when I summon my participant's TimeWindow Collection that i've gotten through the DataBase in the Config class. In the debugger my Participant looks like this

  id:123
  name:"hisName"
  number:"321"
  details:"some details"
  registeredTimeWindow:{PersistentBag@10927}Unable to evaluate the expression Method threw 'org.hibernate.LazyInitializationException' exception.
  

  At first i thought it was normal because of the Lazy option, i had to invoke the array through the getter, however it is wrong and the getter give me the exact same object.

  FetchType.EAGER works fine, however I can't afford to do it. I've tried to get some help from someone a bit more experienced than I am, but without success. It should be possible to work around that issue within the JPA Repositories, but it feels like such a waste not to be able to use the getter.
• Mapping between two classes with JpaRepository SpringBoot

  Well I have a class Service and a class Employee

  Service.java

  import lombok.Data;
  import javax.persistence.*;
  
  @Data
  @Table(name = "services")
  @Entity
  public class ServiceResource {
      @Id
      @GeneratedValue(strategy = GenerationType.IDENTITY)
      private Integer id;
      private String name;
      private String date;
      private String longitude;
      private String latitude;
      @ManyToOne
      @JoinColumn(name="employee_id")
      private EmployeeResource employee;
  
  
  }
  

  Employee.java

  import lombok.Data;
  import javax.persistence.*;
  
  @Data
  @Table(name = "employees")
  @Entity
  public class EmployeeResource {
      @Id
      @GeneratedValue(strategy = GenerationType.IDENTITY)
      private Integer id;
      private String name;
      private String longitude;
      private String latitude;
  
  
  }
  

  Now I'd like to build my application that the mapping between service and employee is done with JPA. Is that even possible and how?
• Why dose the my service class's createPerson() return null?

  I can't find the problem. Here are my classes:

  Test class :

  PersonService :

  

  PersonRepository:
• Spring custom sorting in Sort.of

  Is there any way to use Sort.of with this kind of sorting?

      @Query("SELECT l FROM Livestream l WHERE l.status IN ('LIVE', 'FUTURE') ORDER BY CASE WHEN l.status = 'LIVE' THEN -1 ELSE 0 END ASC")
      fun findLiveAndFuture(pageable: Pageable): Page<Livestream>
  
• Why application is failing to start for findAll method with Specifications?

  I'm using spring-data-dynamodb in my boot app.

  Repository class:

  //.. imports
  class MyRepository extends PagingAndSortingRepository<User, String> {
      Page<User> findByName(String name, Pageable pageable);
      Page<User> findByJoinedDateBetween(String startDate, String endDate, Pageable pageable);
  
      @EnableScan
      @EnableScanCount
      Page<User> findAll(Pageable pageable);
  }
  

  With above repository class, the application starts and returns expected output.

  But, with below repository class setup (adding JpaSpecificationExecutor<User>):

  //.. imports
  class MyRepository extends PagingAndSortingRepository<User, String>, JpaSpecificationExecutor<User>  {
      Page<User> findByName(String lastName, Pageable pageable);
      Page<User> findByJoinedDateBetween(String startDate, String endDate, Pageable pageable);
  
      @EnableScan
      @EnableScanCount
      Page<User> findAll(Specification<User> specs, Pageable pageable);
  }
  

  the app is failing to start with:

  org.springframework.data.mapping.PropertyReferenceException: No property findAll found for type User!
  

  Am I not using it correctly? Is this because there is no support for Specifications at spring-data-dynamodb? Are @EnableDynamoDBRepositories and JpaSpecificationExecutor<User> compatible?
• Java Spring Data : Sort By ID Desc

  I just want my Data to be sorted by ID Descendent and i don't know how to do and this is my code in service layer

  public Page<Facture> selectByPage(Pageable p) {
      Page<Facture> pagedResult = factureRepository.findAll(p);
      return pagedResult;
  }