Develop Reference

Deleting an element from the database observing the id order in Room [Java Android]

When I delete element from database my id stop go in order. Example:
Before deleting:
| ID | | ELEMENT|
| 1 | | text1 |
| 2 | | text2 |
| 3 | | text3 |
After deleting 2nd element:
| ID | | ELEMENT|
| 1 | | text1 |
| 3 | | text3 |
But I need the id to go in order. Example:
| ID | | ELEMENT|
| 1 | | text1 |
| 2 | | text3 |
I have this deleting method in Dao:
#Query("DELETE FROM database WHERE id = :itemId")
void deleteByItemId(long itemId);
How most effective way for solving this problem?

Spark - sample() function duplicating data?

I want to randomly select a subset of my data and then limit it to 200 entries. But after using the sample() function, I'm getting duplicate rows, and I don't know why. Let me show you:
DataFrame df= sqlContext.sql("SELECT * " +
" FROM temptable" +
" WHERE conditions");
DataFrame df1 = df.select(df.col("col1"))
.where(df.col("col1").isNotNull())
.distinct()
.orderBy(df.col("col1"));
df.show();
System.out.println(df.count());
Up until now, everything is OK. I get the output:
+-----------+
|col1 |
+-----------+
| 10016|
| 10022|
| 100281|
| 10032|
| 100427|
| 100445|
| 10049|
| 10070|
| 10076|
| 10079|
| 10081|
| 10082|
| 100884|
| 10092|
| 10099|
| 10102|
| 10103|
| 101039|
| 101134|
| 101187|
+-----------+
only showing top 20 rows
10512
with 10512 records without duplicates. AND THEN!
df = df.sample(true, 0.5).limit(200);
df.show();
System.out.println(users.count());
This returns 200 rows full of duplicates:
+-----------+
|col1 |
+-----------+
| 10022|
| 100445|
| 100445|
| 10049|
| 10079|
| 10079|
| 10081|
| 10081|
| 10082|
| 10092|
| 10102|
| 10102|
| 101039|
| 101134|
| 101134|
| 101134|
| 101345|
| 101345|
| 10140|
| 10141|
+-----------+
only showing top 20 rows
200
Can anyone tell me why? This is driving me crazy. Thank you!

You explicitly ask for a sample with replacement so there is nothing unexpected about getting duplicates:
public Dataset<T> sample(boolean withReplacement, double fraction)

How to resolve Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 2?

Can somebody help me solving this type of error
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 2
I am searching for data in linked list but when I want to insert the data into an array, it turn up to be like this:
matric | nama | sem | cc | ch | fm
32255 | izzat | 1 | ccs2 | 3 | 45.0
| | 2 | ccs3 | 3 | 56.0
32345 | khai] | 3 | ccs4 | 3 | 45.0
| | 2 | ccs5 | 3 | 2.0
32246 | fifi | 1 | cc1 | 3 | 60.0
| | 1 | ccs3 | 4 | 34.0
34567 | dudu | 2 | ccs2 | 2 | 24.0
| | 2 | ccs4 | 6 | 79.0
first-->34567-->32246-->32345-->32255-->null
first-->6-->2-->4-->3-->3-->3-->3-->3-->null
first-->2-->2-->1-->1-->2-->3-->2-->1-->null
first-->dudu-->fifi-->khai]-->izzat-->null
first-->ccs4-->ccs2-->ccs3-->cc1-->ccs5-->ccs4-->ccs3-->ccs2-->null
first-->79.0-->24.0-->34.0-->60.0-->2.0-->45.0-->56.0-->45.0-->null
42insert matric= 032345
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 2
2
khai]
2
3
at inputoutput.LinkedList.getcc(LinkedList.java:141)
at inputoutput.baca.getcc(baca.java:84)
at inputoutput.Inputoutput.main(Inputoutput.java:75)
Java Result: 1
BUILD SUCCESSFUL (total time: 7 seconds)
the code:
String[] getcc(int mat,int sub) {
ListObject2 current = first2;
int count=0;
String b[]=new String[2] ;//2 is the subject number==sub
int x=0;
while (current!=null ) {
if(count==((mat*sub)+x) && ((mat*sub)+0)<((mat*sub)+x)<<((mat*sub)+sub)){
b[x]=current.data2;
x++;
}
current=current.next;
count++;
}
return b;
}
but I will get the input if search for last data in the linked list which is 032255
this is the output:
matric | nama | sem | cc | ch | fm
32255 | izzat | 1 | ccs2 | 3 | 45.0
| | 2 | ccs3 | 3 | 56.0
32345 | khai] | 3 | ccs4 | 3 | 45.0
| | 2 | ccs5 | 3 | 2.0
32246 | fifi | 1 | cc1 | 3 | 60.0
| | 1 | ccs3 | 4 | 34.0
34567 | dudu | 2 | ccs2 | 2 | 24.0
| | 2 | ccs4 | 6 | 79.0
first-->34567-->32246-->32345-->32255-->null
first-->6-->2-->4-->3-->3-->3-->3-->3-->null
first-->2-->2-->1-->1-->2-->3-->2-->1-->null
first-->dudu-->fifi-->khai]-->izzat-->null
first-->ccs4-->ccs2-->ccs3-->cc1-->ccs5-->ccs4-->ccs3-->ccs2-->null
first-->79.0-->24.0-->34.0-->60.0-->2.0-->45.0-->56.0-->45.0-->null
42insert matric= 032255
3
izzat
2
1
ccs3//the data i want to search
ccs2//

You're going into the if statement more than twice while walking the list. If you do that, you'll go past the bounds of the b array (which can only hold two values). You should use an ArrayList instead so you can add as many items as you need.

how to get communicate with 3 tables

Hi I have a table parent and its fields are
mysql> select * from parent;
+----+----------+------------+-----------------------------------+---------+------+
| id | category | is_deleted | name | version | cid |
+----+----------+------------+-----------------------------------+---------+------+
| 1 | default | | Front Office | 0 | NULL |
| 2 | default | | Food And Beverage | 0 | NULL |
| 3 | default | | House Keeping | 0 | NULL |
| 4 | default | | General | 0 | NULL |
| 5 | client | | SPA | 0 | NULL |
| 7 | client | | house | 0 | NULL |
| 8 | client | | test | 0 | NULL |
| 9 | client | | ggg | 0 | 1 |
| 10 | client | | dddd | 0 | 1 |
| 11 | client | | test1 | 0 | 1 |
| 12 | client | | java | 0 | 1 |
| 13 | client | | dcfdcddd | 0 | 1 |
| 14 | client | | qqqq | 0 | 1 |
| 15 | client | | nnnnnn | 0 | 1 |
| 16 | client | | category | 0 | 1 |
| 17 | client | | sukant | 0 | 1 |
| 18 | client | | bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb | 0 | 1 |
I have another table parent_question
mysql> select * from parent_question;
+----+------------+---------+-----+------+
| id | is_deleted | version | pid | qid |
+----+------------+---------+-----+------+
| 1 | | 0 | 1 | 1 |
| 2 | | 0 | 1 | 2 |
| 3 | | 0 | 1 | 3 |
| 4 | | 0 | 1 | 4 |
| 5 | | 0 | 1 | 5 |
| 6 | | 0 | 1 | 6 |
| 7 | | 0 | 2 | 7 |
| 8 | | 0 | 2 | 1 |
| 9 | | 0 | 2 | 2 |
| 10 | | 0 | 2 | 8 |
| 11 | | 0 | 3 | 9 |
| 12 | | 0 | 3 | 1 |
| 13 | | 0 | 3 | 10 |
| 14 | | 0 | 3 | 11 |
| 15 | | 0 | 4 | 12 |
| 16 | | 0 | 1 | 1 |
| 17 | | 0 | 1 | 2 |
| 18 | | 0 | 1 | 3 |
| 19 | | 0 | 5 | 13 |
| 20 | | 0 | 2 | 7 |
| 21 | | 0 | 2 | 2 |
| 22 | | 0 | 1 | 14 |
| 23 | | 0 | 1 | 15 |
| 24 | | 0 | 1 | 16 |
| 25 | | 1 | 1 | 17 |
| 26 | | 0 | 1 | 21 |
| 27 | | 0 | 2 | 22 |
| 28 | | 0 | 13 | 23 |
| 29 | | 0 | 9 | 24 |
| 30 | | 0 | 12 | 25 |
| 31 | | 0 | 12 | 26 |
| 32 | | 0 | 12 | 27 |
| 33 | | 0 | 12 | 28 |
| 34 | | 0 | 14 | 29 |
| 35 | | 0 | 15 | 30 |
| 36 | | 0 | 10 | 31 |
| 37 | | 0 | 4 | 32 |
| 38 | | 0 | 16 | 33 |
| 39 | | 0 | 10 | 34 |
| 40 | | 0 | 3 | 35 |
| 41 | | 0 | 17 | 36 |
| 42 | | 0 | 1 | 37 |
| 43 | | 0 | 1 | 38 |
| 44 | | 0 | 18 | 39 |
| 45 | | 0 | 18 | 40 |
+----+------------+---------+-----+------+
45 rows in set (0.00 sec)
and this is my question table
ysql> select * from question;
----+----------+------------+------------------------------------------------------------+--
id | category | is_deleted | question | v
----+----------+------------+------------------------------------------------------------+--
1 | default | | Staff Courtesy |
2 | default | | Staff Response |
3 | default | | Check In |
4 | default | | Check Out |
5 | default | | Travel Desk |
6 | default | | Door Man |
7 | default | | Restaurant Ambiance |
8 | default | | Quality Of Food |
9 | default | | Cleanliness Of The Room |
10 | default | | Room Size |
11 | default | | Room Amenities |
12 | default | | Any Other Comments ? |
13 | client | | How is Food? |
14 | client | | test question |
15 | client | | test1 |
16 | client | | test2 |
17 | client | | test2 |
18 | client | | test2 |
19 | client | | working |
20 | client | | sss |
21 | client | | ggggg |
22 | client | | this is new question |
23 | client | | dddddddddddd |
24 | client | | ggggggggggggggggg |
25 | client | | what is a class? |
26 | client | | what is inheritance |
27 | client | | what is an object |
28 | client | | what is an abstract class? |
29 | client | | qqqq |
30 | client | | nnnn question |
31 | client | | add some |
32 | client | | general question |
33 | client | | category question |
34 | client | | hhhhhhhh |
35 | client | | this is hos |
36 | client | | gggg |
37 | client | | dddd |
38 | client | | ddddd |
39 | client | | bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb |
40 | client | | ggg |
----+----------+------------+------------------------------------------------------------+--
what I know I have pid of parent_question table;
What I want question of question table;
for example.If I were given to find the question whose pid is 18.
So from the parent_question table I can know qid is 39 and 40 and from the question table 39 refers to bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb and 40 refers to ggg
What i tried
String queryString="SELECT distinct q FROM Question q , ParentQuestion pq ,Parent p where pq.qid.id = q.id and p.id = pq.pid.id and p.category = 'default' AND p.id = "+pid;
Query query=entityManagerUtil.getQuery(queryString);
List questionsList = query.getResultList();
return questionsList;
but it did not work.I mean I get nothing in the list.Can anybody point out my mistake.
question entity class
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Version;
import javax.validation.constraints.Size;
import org.springframework.beans.factory.annotation.Configurable;
#Configurable
#Entity
public class Question {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "id")
private Long id;
#Version
#Column(name = "version")
private Integer version;
private String question;
private String category;
private boolean isDeleted;
public boolean isDeleted() {
return isDeleted;
}
public void setDeleted(boolean isDeleted) {
this.isDeleted = isDeleted;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public Integer getVersion() {
return version;
}
public void setVersion(Integer version) {
this.version = version;
}
public String getQuestion() {
return question;
}
public void setQuestion(String question) {
this.question = question;
}
public String getCategory() {
return category;
}
public void setCategory(String category) {
this.category = category;
}
}
parent entity class
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
import javax.persistence.Version;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import org.springframework.beans.factory.annotation.Configurable;
#Configurable
#Entity
public class Parent {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "id")
private Long id;
#Version
#Column(name = "version")
private Integer version;
#ManyToOne
private Client cid;
public Client getCid() {
return cid;
}
public void setCid(Client cid) {
this.cid = cid;
}
private boolean isDeleted;
/* #ManyToOne
private Client cid;
public Client getCid() {
return cid;
}
public void setCid(Client cid) {
this.cid = cid;
}*/
public boolean isDeleted() {
return isDeleted;
}
public void setDeleted(boolean isDeleted) {
this.isDeleted = isDeleted;
}
private String name;
private String category;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public Integer getVersion() {
return version;
}
public void setVersion(Integer version) {
this.version = version;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getCategory() {
return category;
}
public void setCategory(String category) {
this.category = category;
}
}

Commenters are confused by your classes, and this is a good indication that you might need to think about your design. suninsky has a good point that you may not need to have an entity class call ParentQuestion (unless ParentQuestion has extra data about the relationship, of course). Here are some typical questions I would be asking.
Does every Question have a Parent? If so then there should probably be a parent property on your Question class, mapped as #ManyToOne
Does every a Parent object have a set of Questions? If yes, then the Parent object should probably have a property named questions, the type of which is some kind of collection of Question objects.

Spring MVC 3 with Hibernate - Whats my model for use in ModelAndView?

I've just setup my first Spring MVC 3 project with Hibernate 3 using Maven.
Now I'm used to having a controller-page with my controller and a model package with my models,
but with hibernate integrated what i now have is:
.
|____main
| |____java
| | |____com
| | | |____cqrify
| | | | |____tellus
| | | | | |____App.java
| | | | | |____controller
| | | | | | |____ContactController.java
| | | | | |____dao
| | | | | | |____ContactDAO.java
| | | | | | |____impl
| | | | | | | |____ContactDAOImpl.java
| | | | | |____form
| | | | | | |____Contact.java
| | | | | |____service
| | | | | | |____ContactService.java
| | | | | | |____impl
| | | | | | | |____ContactServiceImpl.java
| |____resources
| | |____config.properties
| | |____log4j.xml
| | |____Messages.properties
| | |____META-INF
| |____webapp
| | |____resources
| | | |____css
| | | |____gfx
| | | |____js
| | |____WEB-INF
| | | |____classes
| | | |____spring
| | | | |____appServlet
| | | | | |____servlet-context.xml
| | | | |____root-context.xml
| | | |____views
| | | | |____editContact.jsp
| | | | |____newContact.jsp
| | | | |____showContacts.jsp
| | | | |____includes
| | | | |____taglib_includes.jsp
| | | |____web.xml
|____test
| |____java
| |____resources
| | |____log4j.xml
|____test.txt
What I understand is that I'm to autowire "ContactService" as that is now my "model", but how do I use with with ModelAndView?
My controller
import com.cqrify.tellus.form.Contact;
import com.cqrify.tellus.service.ContactService;
#Controller
public class ContactController {
#Autowired
private ContactService contactService;
#RequestMapping(value="/")
public ModelAndView listContacts(){
Map<String, Object> contactMap;
contactMap.put("contactList", contactService.listContacts());
ModelAndView modelAndView = new ModelAndView("showContacts", "ContactService", contactMap);
return modelAndView;
}
}
As seen above
ModelAndView modelAndView = new ModelAndView("showContacts", "ContactService", contactMap);
is this right that "ContactService" will now be my modelName or have i completely missed something?

In your case you can simply return:
new ModelAndView("showContacts", "contactList", contactService.listContacts());
This means that you want to render showContacts view and the list of contacts will be available for the view under contactList name.
ContactService is a business object used to find (fetch) the model, IMHO it should not be used to name the model itself.