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  • OPTICS Clustering algorithm. How to get the best epsilon

    - by Marco Galassi
    I am implementing a project which needs to cluster geographical points. OPTICS algorithm seems to be a very nice solution. It needs just 2 parameters as input(MinPts and Epsilon), which are, respectively, the minimum number of points needed to consider them as a cluster, and the distance value used to compare if two points are in can be placed in same cluster. My problem is that, due to the extreme variety of the points, I can't set a fixed epsilon. Just look at the image below. The same points structure but in a different scale would result very different. Suppose to set MinPts=2 and epsilon = 1Km. On the left, the algorithm would create 2 clusters(red and blue), but on the right it would create one single cluster containing all of the points(red), but I would like to obtain 2 clusters even on the right. So my question is: is there any kind of way to calculate dynamically the epsilon value to get this result? Thank you very much and excuse my for my poor english. Marco

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  • Apply Quaternion to Camera in libGDX

    - by Alex_Hyzer_Kenoyer
    I am trying to rotate my camera using a Quaternion in libGDX. I have a Quaternion created and being manipulated but I have no idea how to apply it to the camera, everything I've tried hasn't moved the camera at all. Here is how I set up the rotation Quaternion: public void rotateX(float amount) { tempQuat.set(tempVector.set(1.0f, 0.0f, 0.0f), amount * MathHelper.PIOVER180); rotation = rotation.mul(tempQuat); } public void rotateY(float amount) { tempQuat.set(tempVector.set(0.0f, 1.0f, 0.0f), amount * MathHelper.PIOVER180); rotation = tempQuat.mul(rotation); } Here is how I am trying to update the camera (Same update method as the original libGDX version but I added the part about the rotation matrix to the top): public void update(boolean updateFrustum) { float[] matrix = new float[16]; rotation.toMatrix(matrix); Matrix4 m = new Matrix4(); m.set(matrix); camera.view.mul(m); //camera.direction.mul(m).nor(); //camera.up.mul(m).nor(); float aspect = camera.viewportWidth / camera.viewportHeight; camera.projection.setToProjection(Math.abs(camera.near), Math.abs(camera.far), camera.fieldOfView, aspect); camera.view.setToLookAt(camera.position, tempVector.set(camera.position).add(camera.direction), camera.up); camera.combined.set(camera.projection); Matrix4.mul(camera.combined.val, camera.view.val); if (updateFrustum) { camera.invProjectionView.set(camera.combined); Matrix4.inv(camera.invProjectionView.val); camera.frustum.update(camera.invProjectionView); } }

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  • Is it valid for Hibernate list() to return duplicates?

    - by skaffman
    Is anyone aware of the validity of Hibernate's Criteria.list() and Query.list() methods returning multiple occurrences of the same entity? Occasionally I find when using the Criteria API, that changing the default fetch strategy in my class mapping definition (from "select" to "join") can sometimes affect how many references to the same entity can appear in the resulting output of list(), and I'm unsure whether to treat this as a bug or not. The javadoc does not define it, it simply says "The list of matched query results." (thanks guys). If this is expected and normal behaviour, then I can de-dup the list myself, that's not a problem, but if it's a bug, then I would prefer to avoid it, rather than de-dup the results and try to ignore it. Anyone got any experience of this?

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  • Transactions in hibernate

    - by kumar1425
    Hi I new to hibernate In my project, i need to handle transactions. How to handle declarative transactions with in two classes Examples: //class 1 class A{ createA() { insert(A); } } //class 2 class B { createB() { insert(B); } } //class 3 @Transaction(Exception.class) class C { test() { create(A); create(B); } } As per the above code is there any possibility to handle transactions, in such a way that if the insert in classA success and the insert in the classB fails then the transaction should rollback and remove the record inserted in the table A corresponding to the Class A please help me with this using declarative transactions.... Thanks in adavace....

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  • Tomcat: recommandations for logging

    - by WizardOfOdds
    I've read several questions here concerning Tomcat and logging but I still really don't understand the "bigger picture", hence my question: How and where are my Webapps supposed to do their logging? By default on my setup Tomcat 6.0.20 logs go in the following file/appender: ./apache-tomcat-6.0.20/logs/catalina.out Am I suppose to have my webapps also log to this file/appender? Let say my case is trivially simple and I've got just one servlet: import ... // What do I import here in order to be able to log? public class SOServlet extends HttpServlet { public void doGet( final HttpServletRequest request, final HttpServletResponse response ) throws IOException, ServletException { ... // I want to log here, what do I write? What are the gotchas knowing that there are more than one webapp running on the same Tomcat? (apparently from reading the various questions there are many gotchas). What about the .war, do I need to put log4j/sl4f/commons-logging/whatever in my .war?

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  • Eclipselink: Create objects from JOIN query

    - by Raven
    Hi, I have a SQL query SELECT * FROM Thing AS a JOIN Thing_Property AS b ON a.id=b.Thing_ID JOIN Property AS c ON b.properties_ID = c.id JOIN Item AS d ON c.item_ID = d.id ORDER BY a.name, d.name and I Eclipselink to create my object model with it. Here is the model: @SuppressWarnings("serial") @Entity public class Thing implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; private String name; @OneToMany(cascade=CascadeType.ALL) @PrivateOwned private List<Property> properties = new ArrayList<Property>(); ... // getter and setter following here } public class Property implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; @OneToOne private Item item; private String value; ... // getter and setter following here } public class Item implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; private String name; .... // getter and setter following here } // Code end but I can not figure out, how to make Eclipselink create the model from that query. Can you help?

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  • Are there any reasons to make all fields and variables final?

    - by Roman
    In my current project I noticed that all class fields and variable inside methods are declared with final modifier whenever it's possible. Just like here: private final XMLStreamWriter _xmlStreamWriter; private final Marshaller _marshaller; private final OutputStream _documentStream; private final OutputStream _stylesStream; private final XMLStreamWriter _stylesStreamWriter; private final StyleMerger _styleMerger; public DocumentWriter(PhysicalPackage physicalPackage) throws IOException { final Package pkg = new Package(physicalPackage); final Part wordDocumentPart = pkg.createPart( "/word/document.xml", "application/vnd.openxmlformats-officedocument.wordprocessingml.document.main+xml", "http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument"); // styles.xml final Pair<Part, String> wordStylesPart = wordDocumentPart.createRelatedPart(...); ... } Are there any reasons to do so? p.s. As I know project is not supposed to be multithreaded (at least I've heard nothing about it).

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  • Hibernate noob fetch join problem

    - by Bruce
    Hi all I have two classes, Test2 and Test3. Test2 has an attribute test3 that is an instance of Test3. In other words, I have a unidirectional OneToOne association, with test2 having a reference to test3. When I select Test2 from the db, I can see that a separate select is being made to get the details of the associated test3 class. This is the famous 1+N selects problem. To fix this to use a single select, I am trying to use the fetch=join annotation, which I understand to be @Fetch(FetchMode.JOIN) However, with fetch set to join, I still see separate selects. Here are the relevant portions of my setup.. hibernate.cfg.xml: <property name="max_fetch_depth">2</property> Test2: public class Test2 { @OneToOne (cascade=CascadeType.ALL , fetch=FetchType.EAGER) @JoinColumn (name="test3_id") @Fetch(FetchMode.JOIN) public Test3 getTest3() { return test3; } NB I set the FetchType to EAGER out of desperation, even though it defaults to EAGER anyway for OneToOne mappings, but it made no difference. Thanks for any help! Edit: I've pretty much given up on trying to use FetchMode.JOIN - can anyone confirm that they have got it to work ie produce a left outer join? In the docs I see that "Usually, the mapping document is not used to customize fetching. Instead, we keep the default behavior, and override it for a particular transaction, using left join fetch in HQL" If I do a left join fetch instead: query = session.createQuery("from Test2 t2 left join fetch t2.test3"); then I do indeed get the results I want - ie a left outer join in the query.

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  • JSF, How to set a property in a different page/backing bean and then navigate to that page?

    - by kgrad
    I am using JSF 2.0 and attempting to pass values between different pages in my App. The setup is as follows: I have a page called userSelect that has a backing bean userSelectBacking. On this page I display a list of users that can be selected and submit using an h:commandbutton, when the page is submit the navigation goes to a userEdit page. I have a page called userEdit, that has a backing bean userEditBacking which displays the information for a user and allows that user to be edited. I would like to pass the user selected from the userSelect page into the userEdit page. I am currently using f:setPropertyActionListener to set the user in my userEdit backing from the userSelect page, however when I navigate to the userEdit page, it loses the information I set. is there a way that I can pass the values between the two pages/backing beans? thanks

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  • fail-fast iterator

    - by joy
    I get this definition : As name suggest fail-fast Iterators fail as soon as they realized that structure of Collection has been changed since iteration has begun. what it mean by since iteration has begun? is that mean after Iterator it=set.iterator() this line of code? public static void customize(BufferedReader br) throws IOException{ Set<String> set=new HashSet<String>(); // Actual type parameter added **Iterator it=set.iterator();**

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  • Using Comparable to compare objects and sorting them in a TreeMap

    - by arjacsoh
    II cannot understand how should the natural ordering of class be "consistent with equals" when implementing the Comparable interface. I deteted a flaw in my program and therefore I deteced that in the documentantion of the interface Comparable. My problem is that although two Objects are considered as distinct on the base of equals method, the TreeMap structure treats them as equal and consequently does not accept the second insert. The sample code is: public class Car implements Comparable<Car> { int weight; String name; public Car(int w, String n) { weight=w; name=n; } public boolean equals(Object o){ if(o instanceof Car){ Car d = (Car)o; return ((d.name.equals(name)) && (d.weight==weight)); } return false; } public int hashCode(){ return weight/2 + 17; } public String toString(){ return "I am " +name+ " !!!"; } public int compareTo(Car d){ if(this.weight>d.weight) return 1; else if(this.weight<d.weight) return -1; else return 0; } /*public int compareTo(Car d){ return this.name.compareTo(d.name); }*/ } public static void main(String[] args) { Car d1 = new Car(100, "a"); Car d2 = new Car(110, "b"); Car d3 = new Car(110, "c"); Car d4 = new Car(100, "a"); Map<Car, Integer> m = new HashMap<Car, Integer>(); m.put(d1, 1); m.put(d2, 2); m.put(d3, 3); m.put(d4, 16); for(Map.Entry<Car, Integer> me : m.entrySet()) System.out.println(me.getKey().toString() + " " +me.getValue()); TreeMap<Car, Integer> tm = new TreeMap<Car, Integer>(m); System.out.println("After Sorting: "); for(Map.Entry<Car, Integer> me : tm.entrySet()) System.out.println(me.getKey().toString() + " " +me.getValue()); } The output is : I am a !!! 16 I am c !!! 3 I am b !!! 2 After Sorting: I am a !!! 16 I am c !!! 2 That is, that the object c has replaced (somewhat) object b. If I comment the original equals method and uncomment the second equals method, which compares the objects according name, the output is the expected: I am a !!! 16 I am c !!! 3 I am b !!! 2 After Sorting: I am a !!! 16 I am b !!! 2 I am c !!! 3 Why does it come around in this way and what should I alter in order to insert and sort different objects with some attributes of equal value in a TreeMap?

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  • Andriod Spinner not displaying list items.

    - by user300339
    I think I am going crazy right now. I am trying to create a spinner populated by a datatable but for some reason the dropdown list items text is not being displayed. I have looked all over and have seen other posts with people having this same problem. Can anyone help?? speciesList = (Spinner) findViewById(R.id.speciesList); spinnerCursor = nsfdb.fetchAllSpecies(); startManagingCursor(spinnerCursor); //String []cArrayList = new String[]{"dog", "cat", "horse", "other"}; String[] from = new String[]{"species"}; int[] to = new int[]{R.id.text1}; SimpleCursorAdapter locations = new SimpleCursorAdapter(this, R.layout.loc_row, spinnerCursor, from, to); locations.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); speciesList.setAdapter(locations); The spinner gets created just fine and is populated with 4 items but whenever I click on the spinner I see 4 items with no text and just radiobuttons. If I select any of them I am getting the correct selected item value but there is just no data displayed.

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  • Source code versioning with comments (organizational practice) - leave or remove?

    - by ADTC
    Before you start admonishing me with "DON'T DO IT," "BAD PRACTICE!" and "Learn to use proper source code control", please hear me out first. I am fully aware that the practice of commenting out old code and leaving it there forever is very bad and I hate such practice myself. But here's the situation I'm in. A few months ago I joined a company as software developer. I had worked in the company for few months as an intern, about a year before joining recently. Our company uses source code version control (CVS) but not properly. Here's what happened both in my internship and my current permanent position. Each time I was assigned to work on a project (legacy, about 8-10 years old). Instead of creating a CVS account and letting me check out code and check in changes, a senior colleague exported the code from CVS, zipped it up and passed it to me. While this colleague checks in all changes in bulk every few weeks, our usual practice is to do fine-grained versioning in the actual source code itself (each file increments in versions independent from the rest). Whenever a change is made to a file, old code is commented out, new code entered below it, and this whole section is marked with a version number. Finally a note about the changes is placed at the top of the file in a section called Modification History. Finally the changed files are placed in a shared folder, ready and waiting for the bulk check-in. /* * Copyright notice blah blah * Some details about file (project name, file name etc) * Modification History: * Date Version Modified By Description * 2012-10-15 1.0 Joey Initial creation * 2012-10-22 1.1 Chandler Replaced old code with new code */ code .... //v1.1 start //old code new code //v1.1 end code .... Now the problem is this. In the project I'm working on, I needed to copy some new source code files from another project (new in the sense that they didn't exist in destination project before). These files have a lot of historical commented out code and comment-based versioning including usually long or very long Modification History section. Since the files are new to this project I decided to clean them up and remove unnecessary code including historical code, and start fresh at version 1.0. (I still have to continue the practice of comment-based versioning despite hating it. And don't ask why not start at version 0.1...) I have done similar something during my internship and no one said anything. My supervisor has seen the work a few times and didn't say I shouldn't do such clean-up (if at all it was noticed). But a same-level colleague saw this and said it's not recommended as it may cause downtime in the future and increase maintenance costs. An example is when changes are made in another project on the original files and these changes need to be propagated to this project. With code files drastically different, it could cause confusion to an employee doing the propagation. It makes sense to me, and is a valid point. I couldn't find any reason to do my clean-up other than the inconvenience of a ridiculously messy code. So, long story short: Given the practice in our company, should I not do such clean-up when copying new files from project to project? Is it better to make changes on the (copy of) original code with full history in comments? Or what justification can I give for doing the clean-up? PS to mods: Hope you allow this question some time even if for any reason you determine it to be unfit in SO. I apologize in advance if anything is inappropriate including tags.

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  • Lackadaisical One-to-One between Char and Byte Streams

    - by Vaibhav Bajpai
    I expected to have a one-to-one correspondence between the character streams and byte streams in terms of how the classes are organized in their hierarchy. FilterReader and FilterWriter (character streams) correspond back to FilterInputStream and FilterOutputStream (byte stream) classes. However I noticed few changes as - BufferedInputStream extends FilterInputStream, but BufferedReader does NOT extend FilterReader. BufferedOutputStream and PrintStream both extend FilterOutputStream, but BufferedWriter and PrintWriter does NOT extend FilterWriter. FilterInputStream and FilterOutputStream are not abstract classes, but FilterReader and FilterWriter are. I am not sure if I am being too paranoid to point out such differences, but was just curious to know if there was design reasoning behind such decision.

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  • SWT: scrollable area within a tab

    - by DaveJohnston
    I am trying to add a scrollable area to my tabbed window. So far I have a CTabFolder in a shell. I have added 5 CTabItems to it and everything works as expected. On one of my CTabItems the contents are too big to fit on the screen so I would like to be able to scroll. The contents is a collection of Groups each containing various widgets. So the CTabFolder is created as follows: CTabFolder tabs = new CTabFolder(shell, SWT.BORDER); tabs.setSimple(false); tabs.setUnselectedImageVisible(false); tabs.setUnselectedCloseVisible(false); tabs.setMinimizeVisible(false); tabs.setMaximizeVisible(false); FormData tabsLayoutData = new FormData(); tabsLayoutData.top = new FormAttachment(0, 5); tabsLayoutData.left = new FormAttachment(0, 5); tabsLayoutData.bottom = new FormAttachment(92, 0); tabsLayoutData.right = new FormAttachment(100, -5); tabs.setLayoutData(tabsLayoutData); Then the CTabItem: CTabItem tab = new CTabItem(tabs, SWT.NONE); tab.setText("Role"); Then the contents: Composite tabArea = new Composite(tabs, SWT.V_SCROLL); tabArea.setLayout(new FormLayout()); tab.setControl(tabArea); So the groups contained within the tab are created with tabArea as the parent and everything appears as you would expect. The problem is though that the vertical scroll bar is always present but doesn't seem to do anything. The contents are chopped off at the bottom of the tabArea composite. Is there anything else I need to do to get the scrolling to work properly?

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  • Issue calling superclass method in subclass constructor

    - by stormin986
    I get a NullPointerException calling a Superclass Method in Subclass Inner Class Constructor... What's the Deal? In my application's main class (subclass of Application), I have a public inner class that simply contains 3 public string objects. In the parent class I declare an object of that inner class. public class MainApplication extends Application { public class Data { public String x; public String y; public String z; } private Data data; MainApplication() { data = new Data() data.x = SuperClassMethod(); } } After I instantiate the object in the constructor, I get a runtime error when I try to assign a value in the inner class with a superclass method. Any idea what's up here?? Can you not call superclass methods in the subclass constructor? ** Edit ** Original question was about inner class member assignment in outer class constructor. Turned out the issue was with calling a superclass method in the class's constructor. It was giving me a null pointer exception. Thus, the question has changed.

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  • Finding Palindromes in an Array

    - by Jack L.
    For this assignemnt, I think that I got it right, but when I submit it online, it doesn't list it as correct even though I checked with Eclipse. The prompt: Write a method isPalindrome that accepts an array of Strings as its argument and returns true if that array is a palindrome (if it reads the same forwards as backwards) and /false if not. For example, the array {"alpha", "beta", "gamma", "delta", "gamma", "beta", "alpha"} is a palindrome, so passing that array to your method would return true. Arrays with zero or one element are considered to be palindromes. My code: public static void main(String[] args) { String[] input = new String[6]; //{"aay", "bee", "cee", "cee", "bee", "aay"} Should return true input[0] = "aay"; input[1] = "bee"; input[2] = "cee"; input[3] = "cee"; input[4] = "bee"; input[5] = "aay"; System.out.println(isPalindrome(input)); } public static boolean isPalindrome(String[] input) { for (int i=0; i<input.length; i++) { // Checks each element if (input[i] != input[input.length-1-i]){ return false; // If a single instance of non-symmetry } } return true; // If symmetrical, only one element, or zero elements } As an example, {"aay", "bee", "cee", "cee", "bee", "aay"} returns true in Eclipse, but Practice-It! says it returns false. What is going on?

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  • Counting down to zero in contrast to counting up to length - 1

    - by Helper Method
    Is it recommended to count in small loops (where possible) down from length - 1 to zero instead of counting up to length - 1? 1.) Counting down for (int i = a.length - 1; i >= 0; i--) { if (a[i] == key) return i; } 2.) Counting up for (int i = 0; i < a.length; i++) { if (a[i] == key) return i; } The first one is slightly faster that the second one (because comparing to zero is faster) but is a little more error-prone in my opinion. Besides, the first one could maybe not be optimized by future improvements of the JVM. Any ideas on that?

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  • Make my radio buttons become selected in Android

    - by NickTFried
    When I run this could and click on the dialog box my radiobuttons do not become selected like intended package edu.elon.cs.mobile; import edu.elon.cs.mobile.R; import edu.elon.cs.mobile.R.id; import edu.elon.cs.mobile.R.layout; import android.app.Activity; import android.app.AlertDialog; import android.content.DialogInterface; import android.os.Bundle; import android.text.Editable; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; import android.widget.RadioButton; import android.widget.TextView; import android.widget.Toast; public class PTCalculator extends Activity{ private RadioButton maleRadioButton; private RadioButton femaleRadioButton; private EditText ageEdit; private EditText pushUpsEdit; private EditText sitUpsEdit; private EditText mileMinEdit; private EditText mileSecEdit; private Button calculate; private TextView score; protected AlertDialog genderAlert; private int currScore; private int age; private int sitUps; private int runTime; private int pushUps; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.pt); maleRadioButton = (RadioButton) findViewById(R.id.male); femaleRadioButton = (RadioButton) findViewById(R.id.female); ageEdit = (EditText) findViewById(R.id.ageEdit); pushUpsEdit = (EditText) findViewById(R.id.pushupEdit); sitUpsEdit = (EditText) findViewById(R.id.situpEdit); mileMinEdit = (EditText) findViewById(R.id.minEdit); mileSecEdit = (EditText) findViewById(R.id.secEdit); calculate = (Button) findViewById(R.id.calculateButton); calculate.setOnClickListener(calculateButtonListener); score = (TextView) findViewById(R.id.scoreView); genderAlert = makeGenderDialog().create(); } private OnClickListener calculateButtonListener = new OnClickListener() { @Override public void onClick(View arg0) { age = (Integer.parseInt(ageEdit.getText().toString())); pushUps = (Integer.parseInt(pushUpsEdit.getText().toString())); sitUps = (Integer.parseInt(sitUpsEdit.getText().toString())); int min = (Integer.parseInt(mileMinEdit.getText().toString())*60); int sec = (Integer.parseInt(mileSecEdit.getText().toString())); runTime = min + sec; if(maleRadioButton.isChecked()){ MalePTTest mPTTest = new MalePTTest(age, pushUps, sitUps, runTime); currScore = mPTTest.malePTScore(); score.setText((Integer.toString(currScore))); }else if(femaleRadioButton.isChecked()){ FemalePTTest fPTTest = new FemalePTTest(age, pushUps, sitUps, runTime); currScore = fPTTest.femalePTScore(); score.setText((Integer.toString(currScore))); }else genderAlert.show(); } }; public AlertDialog.Builder makeGenderDialog(){ AlertDialog.Builder builder = new AlertDialog.Builder(this); builder.setMessage("Select a Gender") .setCancelable(false) .setPositiveButton("Female", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int id) { femaleRadioButton.setSelected(true); FemalePTTest fPTTest = new FemalePTTest(age, pushUps, sitUps, runTime); currScore = fPTTest.femalePTScore(); score.setText((Integer.toString(currScore))); } }) .setNegativeButton("Male", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int id) { maleRadioButton.setSelected(true); MalePTTest mPTTest = new MalePTTest(age, pushUps, sitUps, runTime); currScore = mPTTest.malePTScore(); score.setText((Integer.toString(currScore))); } }); return builder; } } Any suggestions?

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  • Jpa subclass mapping

    - by Roy Chan
    I am making a POS like system. I wonder how to map subclass using JPA (this is for my DAO). Product class has product details and OrderProduct class has information about the Product and details about the order. @Entity @Table(name="products") public class Product implements Serializable{ @Id @Column(name="id") @GeneratedValue(strategy = GenerationType.AUTO public int getId(){ return id;} /** Other get/set methods */ } @Entity @Table(name="order_products") public class OrderProduct extends Product{ @Id @Column(name="id") @GeneratedValue(strategy = GenerationType.AUTO) public int getId(){ return id;} /** Other get/set methods */ } I got complain about duplicate @Id. But OrderProduct class really need another id than the product one. How should I map this? DB is something like this Table products id int name varchar(32) Table order_product id int quantity int productid int fk referencing product table Would @IdClass or @AttributeOverride help?

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