Deep Clone Of Entities - Set Primary Keys To Null

Nov 21, 2014

I need to get a clone of a fairly deep object tree. All objects are entities and I need to set the primary keys to null. The root object:

public class Grundentscheidung implements Cloneable {
@OneToMany(cascade = CascadeType.ALL)
@JoinColumns({
@JoinColumn(name = "gesamtentscheidung_dstNr"),
@JoinColumn(name = "gesamtentscheidung_id")

[Code] .....

When I call

Grundentscheidung grundentscheidungClone = grundentscheidung.clone();

grundentscheidungClone contains the whole object tree with all dependencies, but the Tatbestand objects have their primary keys. When I use the debugger I see that Tatbestand.clone() is never called.

Is my code faulty? I would like to avoid to write a large method which sets all primary keys on the object tree to null.

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JPA Primary Key From Two Foreign Keys

Oct 22, 2010

I am new with java, eclipse, jpa(eclipselink), postgresql, and trying to make a web application. I have two tables:

bids: id, quantity, price

trades: bidid, askid, quantity, price

bidid and askid columns are foreign keys from bids table (id), and they are the primary key for the trades table.

I created the Entities from the Tables (Bid and Trade class) with eclipse and it generated a TradePK class for the primary key.

Trade.java:

@Entity
@Table(name="trades")
public class Trade implements Serializable {
@EmbeddedId
private TradePK id;

[Code] ....

I understand that this is necessary because the primary key is from two column, but as soon I want to persist a Trade back to the database Eclipselink call the column names twice:

INSERT INTO trades (price, quantity, datetime, BIDID, ASKID, bidid, askid) VALUES (?, ?, ?, ?, ?, ?, ?)

So postgres give me back an exception: ERROR: column "bidid" specified more than once

And I don't know why. According to the JPA docs I didn't found any mistake:

Introduction to EclipseLink JPA (ELUG) - Eclipsepedia

Or I just can't see it... or is there a better doc which explains it better?

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Mar 21, 2014

how to do a deep copy of objects that contain references. I am specifically wanting to make a deep copy of a tree. Logically, each tree node contain references to its children nodes. Here is the basics of my node class

public class BSTNode implements Comparable, Serializable {
 
private String token;
private int count;
private BSTNode leftChild;
private BSTNode rightChild;

I know I must only be making a shallow copy because when I make a copy of tree1, called tree2, and edit tree1 the edits also appear on tree2. Here is my copy method within my BSTNode class

public BSTNode copy()
{
BSTNode obj = null;
try{
ByteArrayOutputStream bos = new ByteArrayOutputStream();
ObjectOutputStream out = new ObjectOutputStream(bos);
out.writeObject(this);
out.flush();
out.close();

[code]....

When I wish to copy the entire tree, I call that above copy method from my BSTree class using the methods below. (I have 2 methods because this is a homework assignment that requires a copy method that calls a preorder traversal method)

public BSTNode copy()
{
BSTNode copiedTreeRoot = new BSTNode();
return copyTree(copiedTreeRoot,root);
 
[code]....

And further along when I make changes to tree1, tree 2 also changes. I have no clue what I'm doing wrong. I believe it must be somewhere in how I return the new tree or something.I tried this edit to my copy method, but it made no difference.

public BSTNode copy() {
BSTNode obj = null;
try{
ByteArrayOutputStream bos = new ByteArrayOutputStream();
ObjectOutputStream out = new ObjectOutputStream(bos);
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[code].....

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Oct 31, 2014

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Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Cannot add or update a child row:
a foreign key constraint fails (`testdummy`.`company`, CONSTRAINT `FK_COMPANY_FK_COMPANY_SECTORID` FOREIGN KEY
(`FK_COMPANY_SECTORID`) REFERENCES `sectors` (`SECTORID`))
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)

I'm thinking that the problem is that since the Segment entity is a child of Sector it must be entered through an instance of Sector. Because it's being entered as a separate value I'm getting this error. The problem is Segment is defined as a Set in the Sector entity and I can't figure out how to declare Segment as an instance using its parent entity (Sector).

My code is as follows, starting with the Sector entity:

@Entity
@Table(name = "SECTORSNEW")
public class SectorsNew {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int sectorId;
private String sectorName;
@OneToMany(cascade = CascadeType.PERSIST)

[code]....

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Apr 10, 2015

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May 29, 2014

How do you do validation in java for primary key  lets say the table got combination of two columns as primary key,how can i validate that if use enter already existing value...

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i have a table with two columns as primary key i what to trap exception if the use in UI try to enter duplication in the table i don't what to throw ORA ERROR i what to display meaningful error massage,my database is oracle 11g

this is how i what to do it

i what to add integrity constraint to the table, and i use explicitly name it.

- i test the database to figure out what exception it returns for that constraint. With luck the name i used will be in the text of the exception.

- i add a catch to my database layer that catches SQLException, looks for the error message, and then throws a different exception, probably my own message

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and i have tried ....

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[Code]....

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Jan 20, 2015

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class literalTesting{
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[code]...

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Jun 20, 2014

I want to clone some Arraylist, but the compiler apparently are just referencing the values to it's original ArrayList. I don't know what should it be:

package projetoteste;
import java.util.ArrayList;
import java.util.List;
public class TestFood {
public static void main(String[] args) {
List food=new ArrayList();

[code]....

Notice that ArrayList dailyMeal should be untouchable, but it return the changes that I made in local for-loop iteration although I didn't added nothing to it, just to it's clone.

Output:

[[[Suco, 1 , 2], [Suco, 1 , 2]], [[Suco, 1 , 2], [Suco, 1 , 2]]]
[[[►, ►, Suco, 1 , 2], [►, ►, Suco, 1 , 2]], [[►, ►, Suco, 1 , 2], [►, ►, Suco, 1 , 2]]]

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import javax.swing.*;
import java.awt.Dimension;
import javax.swing.Timer;
import java.awt.Color;
import java.awt.Graphics;
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[Code] ....

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[Code] ....

And the Block class ( the one that all Block Types are based off of):

package game;
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 import java.io.IOException;
import java.nio.FloatBuffer;
 import org.lwjgl.opengl.GL11;
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[Code] ....

And that is the code, I'll make updates as needed.

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Apr 16, 2014

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[code]....

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import java.io.File;
import java.io.FileNotFoundException;
import java.util.Collection;
import java.util.Collections;
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[code].....

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[Code] .....

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Jul 4, 2014

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[Code]....

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[Code] .....

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[Code] ....

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