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  • Are there any garanties in JLS about order of execution static initialization blocks?

    - by Roman
    I wonder if it's reliable to use a construction like: private static final Map<String, String> engMessages; private static final Map<String, String> rusMessages; static { engMessages = new HashMap<String, String> () {{ put ("msgname", "value"); }}; rusMessages = new HashMap<String, String> () {{ put ("msgname", "????????"); }}; } private static Map<String, String> msgSource; static { msgSource = engMessages; } public static String msg (String msgName) { return msgSource.get (msgName); } Is there a possibility that I'll get NullPointerException because msgSource initialization block will be executed before the block which initializes engMessages? (about why don't I do msgSource initialization at the end of upper init. block: just the matter of taste; I'll do so if the described construction is unreliable)

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  • Is Catching a Null Pointer Exception a Code Smell?

    - by Drew
    Recently a co-worker of mine wrote in some code to catch a null pointer exception around an entire method, and return a single result. I pointed out how there could've been any number of reasons for the null pointer, so we changed it to a defensive check for the one result. However, catching NullPointerException just seemed wrong to me. In my mind, Null pointer exceptions are the result of bad code and not to be an expected exception in the system. Are there any cases where it makes sense to catch a null pointer exception?

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  • Is there a concise way to create an InputSupplier for an InputStream in Google Guava?

    - by Fabian Steeg
    There are a few factory methods in Google Guava to create InputSuppliers, e.g. from a byte[]: ByteStreams.newInputStreamSupplier(bytes); Or from a File: Files.newInputStreamSupplier(file); Is there a similar way to to create an InputSupplier for a given InputStream? That is, a way that's more concise than an anonymous class: new InputSupplier<InputStream>() { public InputStream getInput() throws IOException { return inputStream; } }; Background: I'd like to use InputStreams with e.g. Files.copy(...) or ByteStreams.equal(...).

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  • How do you set a double value to a "non-value"

    - by Ankur
    I have two double data elements in an object. Sometimes they are set with a proper value and sometimes not. When the form field from which they values are received is not filled I want to set them to some value that tells me, during the rest of the code that the form fields were left empty. I can't set the values to null as that gives an error, is there some way I can make them 'Undefined'. PS. Not only am I not sure that this is possible, it might not also make sense. But if there is some best practice for such a situation I would be keen to hear it.

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  • JPanel not listening to key event when there is a child component with JButton on it

    - by Yifu
    I'm working on a map editor for my college project. And I had a problem that the map panel is not listening key event while it should. This happens when I add a ToolBarPane (which extends JPanel) with JComponent such as JButton, JComboBox that implements ActionListener on it AND the map panel (which extends the JPanel) together on to the Frame (I used BorderLayout). I have System.out.println statement to test if the key press is received, and it's not printing, if I remove the ToolBar, the key listener works again, so is the mouseListenner is disabled just like the keyListener, which means I can't handle press events etc, but the mouseListener works fine and I can still handle mouse move event. Here is a screen shot how it works without the ToolBarPane http://img684.imageshack.us/img684/3232/sampleku.png note that you can use the mouse to put images on the map, you can also select images using the mouse just like a laser tool, and by pressing number key you can switch between different images, this works fine until I add the ToolBarPane which shows like this: img291.imageshack.us/img291/8020/failve.png (please add http before that, i can only post one hyperlink) (I can't post images here cuz im a new user) With the ToolBarPane on I was no longer able to handle the key event. I guess it might by that the focus as been transfered to that panel somehow, but not sure at all. Does and body know this and can help me out? Thanks very much

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  • Better way to implement custom views in a listview with simpleadapter?

    - by jonaz
    I have a value called tags which is a comma separated list of words. I want to put this into nicely designed "tag-buttons". The below works. However the line ((LinearLayout) view).removeAllViews(); seems like an ugly fix for not adding the tags multiple times every time adapter.notifyDataSetChanged(); is called after i load more rows with a setOnScrollListener() Any suggestion to "best practice" here, or at least a more good looking solution? adapter = new SimpleAdapter(activity,data, R.layout.list_transactions, new String[] {"comment", "amount","date","tags","category"}, new int[] { R.id.comment, R.id.amount,R.id.date,R.id.tags_container,R.id.category } ); SimpleAdapter.ViewBinder binder = new SimpleAdapter.ViewBinder() { @Override public boolean setViewValue(View view, Object object, String value) { //Log.d(TAG,"view.toString()= "+ view.toString()); if (view.getId() == R.id.tags_container) { String[] tags = value.split(","); ((LinearLayout) view).removeAllViews(); for (String tag : tags) { View v = createTagView(activity.getLayoutInflater(),tag); ((LinearLayout) view).addView(v); } return true; } return false; } };

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  • how to avoid if conditions,

    - by kumar kasimala
    Hi all, can anyone suggest best way to avoid most if conditions? I have below code, I want avoid most of cases if conditions, how to do it ? any solution is great help; if (adjustment.adjustmentAccount.isIncrease) { if (adjustment.increaseVATLine) { if (adjustment.vatItem.isSalesType) { entry2.setDebit(adjustment.total); entry2.setCredit(0d); } else { entry2.setCredit(adjustment.total); entry2.setDebit(0d); } } else { if (adjustment.vatItem.isSalesType) { entry2.setCredit(adjustment.total); entry2.setDebit(0d); } else { entry2.setDebit(adjustment.total); entry2.setCredit(0d); } } } else { if (adjustment.increaseVATLine) { if (adjustment.vatItem.isSalesType) { entry2.setCredit(adjustment.total); entry2.setDebit(0d); } else { entry2.setDebit(adjustment.total); entry2.setCredit(0d); } } else { if (adjustment.vatItem.isSalesType) { entry2.setDebit(adjustment.total); entry2.setCredit(0d); } else { entry2.setCredit(adjustment.total); entry2.setDebit(0d); } }

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  • Spring 3: task namespace: How to find out time of next execution?

    - by Bernd Haug
    I have a bean that has a method executed on a schedule using <task:scheduled> in the context configuration. Is there a way for me to find the time of the next scheduled run during execution of that method? The same method is also executed manually, and the mechanism for receiving scheduler information may not break executions from outside the scheduler...

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  • How to get all n sets of three consecutives elements in an array or arraylist with a for statement ?

    - by newba
    Hi, I'm trying to do a convex hull approach and the little problem is that I need to get all sets of three consecutive vertices, like this: private void isConvexHull(Ponto[] points) { Arrays.sort(points); for (int i = 0; i <points.length; i++) { isClockWise(points[i],points[i+1],points[i+2]); } //... } I always do something that I don't consider clean code. Could please help me find one or more ways to this? I want it to be circular, i.e., if my fisrt point of the a set is the last element in the array, the 2nd element will be the 3rd in the list and the 3rd in that set will be the the 2nd element in the list, and so on. They must be consecutive, that's all.

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  • Simple question about the lunarlander example.

    - by Smills
    I am basing my game off the lunarlander example. This is the run loop I am using (very similar to what is used in lunarlander). I am getting considerable performance issues associated with my drawing, even if I draw almost nothing. I noticed the below method. Why is the canvas being created and set to null each cycle? @Override public void run() { while (mRun) { Canvas c = null; try { c = mSurfaceHolder.lockCanvas();//null synchronized (mSurfaceHolder) { updatePhysics(); doDraw(c); } } finally { // do this in a finally so that if an exception is thrown // during the above, we don't leave the Surface in an // inconsistent state if (c != null) { mSurfaceHolder.unlockCanvasAndPost(c); } } } } Most of the times I have read anything about canvases it is more along the lines of: mField = new Bitmap(...dimensions...); Canvas c = new Canvas(mField); My question is: why is Google's example done that way (null canvas), what are the benefits of this, and is there a faster way to do it?

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  • Linking Apache to Tomcat with multiple domains.

    - by Royce Thigpen
    Okay, so I've been working for a while on this, and have been searching, but so far I have not found any answers that actually answer what I want to know. I'm a little bit at the end of my rope with this one, but I'm hoping I can figure this out sometime soon. So I have Apache 2 installed and serving up standard webpages, but I also have that linked to a Tomcat instance for one of my domains currently supported. However, I want to add another domain to the server via Apache that points to a separate code base from the one I already have. I have been coming at this from several different angles, and I have determined that I just don't know enough about setting up these servers to really do what I want to do. Little information on my server: Currently running a single Tomcat5.5 instance with Apache 2, using mod_jk to connect them together. I have a worker in workers.properties that points it's "host" field to "localhost" with the correct port my Tomcat instance, so that all works. In my Tomcat server.xml file, I have a host defined as "localhost" that points at my webapp that I am currently serving up, with that host set as the defaultHost as well. One thought I had was that I could add a new worker with a different host than "localhost" (i.e. host2) and then define a new host in my server.xml file called "host2" to match it, but after reading around some on the internet, It seems the "host" of the worker must point to a server, and not a hostname in the Tomcat instance, is this correct? Again, a simple rundown of what I want: Setup in apache/tomcat combo such that www.domain1.com points at "webapp1" and www.domain2.com points at "webapp2".

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  • How did this get 8?

    - by David
    Here's the code: class qual { public static int fibonacci(int n) { if (n == 0 || n == 1) { return 1; } else { return fibonacci(n-1) + fibonacci(n-2); } } public static void main(String[] arg) { System.out.println(fibonacci(5)); } } The output was 8. The output should be 8 but when I look at this I think it should be 7 ((5-1) +(5-2)). Why was the output 8? I think the reasoning behind getting 8 will make recursion maybe stop being confusing for me.

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  • Is it okay to pass injected EntityManagers to EJB bean's helper classes and use it?

    - by Zwei steinen
    We have some JavaEE5 stateless EJB bean that passes the injected EntityManager to its helpers. Is this safe? It has worked well until now, but I found out some Oracle document that states its implementation of EntityManager is thread-safe. Now I wonder whether the reason we did not have issues until now, was only because the implementation we were using happened to be thread-safe (we use Oracle). @Stateless class SomeBean { @PersistenceContext private EntityManager em; private SomeHelper helper; @PostConstruct public void init(){ helper = new SomeHelper(em); } @Override public void business(){ helper.doSomethingWithEm(); } } Actually it makes sense.. If EntityManager is thread-unsafe, a container would have to do inercept business() this.em = newEntityManager(); business(); which will not propagate to its helper classes. If so, what is the best practice in this kind of a situation? Passing EntityManagerFactory instead of EntityManager?

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  • from loop to Nested loops ?

    - by WM
    I have this program that returns a factorial of N. For example, when entering 4,,, it will give 1! , 2! , 3! How could I convert this to use nested loops? public class OneForLoop { public static void main(String[] args) { Scanner input = new Scanner(System.in); System.out.print("Enter a number : "); int N = input.nextInt(); int factorial = 1; for(int i = 1; i < N; i++) { factorial *= i; System.out.println(i + "! = " + factorial); } } }

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  • Macports 1.8.2 fails to build db46 on os x 1.6.3

    - by themoch
    i'm trying to put a dev environment on my mac, and to do so i need to install several packages which require db46 when running sudo port install db46 i get the following error: ---> Computing dependencies for db46 ---> Fetching db46 ---> Attempting to fetch patch.4.6.21.1 from http://www.oracle.com/technology/products/berkeley-db/db/update/4.6.21/ ---> Attempting to fetch patch.4.6.21.2 from http://www.oracle.com/technology/products/berkeley-db/db/update/4.6.21/ ---> Attempting to fetch patch.4.6.21.3 from http://www.oracle.com/technology/products/berkeley-db/db/update/4.6.21/ ---> Attempting to fetch patch.4.6.21.4 from http://www.oracle.com/technology/products/berkeley-db/db/update/4.6.21/ ---> Attempting to fetch db-4.6.21.tar.gz from http://distfiles.macports.org/db4/4.6.21_6 ---> Verifying checksum(s) for db46 ---> Extracting db46 ---> Applying patches to db46 ---> Configuring db46 ---> Building db46 Error: Target org.macports.build returned: shell command " cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_ports_databases_db46/work/db-4.6.21/build_unix" && /usr/bin/make -j2 all " returned error 2 Command output: ../dist/../libdb_java/db_java_wrap.c:9464: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9487: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jlong' ../dist/../libdb_java/db_java_wrap.c:9509: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9532: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jlong' ../dist/../libdb_java/db_java_wrap.c:9563: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jint' ../dist/../libdb_java/db_java_wrap.c:9588: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jlong' ../dist/../libdb_java/db_java_wrap.c:9613: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jint' ../dist/../libdb_java/db_java_wrap.c:9638: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9666: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jlong' ../dist/../libdb_java/db_java_wrap.c:9691: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jlong' ../dist/../libdb_java/db_java_wrap.c:9716: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9739: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9771: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9796: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9819: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9842: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9867: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jobject' ../dist/../libdb_java/db_java_wrap.c:9899: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9920: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9943: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9966: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jstring' ../dist/../libdb_java/db_java_wrap.c:9991: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jint' ../dist/../libdb_java/db_java_wrap.c:10010: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:10046: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:10071: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' make: *** [db_java_wrap.lo] Error 1 make: *** Waiting for unfinished jobs.... Note: Some input files use unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details. cd ./classes && jar cf ../db.jar ./com/sleepycat Error: Status 1 encountered during processing. i have removed my /usr/local folder completely and it does not seem to help

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  • Flickering when repainting a JPanel inside a JScrollPAne

    - by pR0Ps
    I'm having a problem with repainting a JPanel inside a JScrollPane. Basically, I'm just trying to 'wrap' my existing EditPanel (it originally extended JPanel) into a JScrollPane. It seems that the JPanel updates too often (mass flickering). How would I stop this from happening? I tried using the setIgnoreRepaint() but it didn't seem to do anything. Will this current implementation work or would I need to create another inner class to fine-tune the JPanel I'm using to display graphics? Skeleton code: public class MyProgram extends JFrame{ public MyProgram(){ super(); add(new EditPanel()); pack(); } private class EditPanel extends JScrollPane{ private JPanel graphicsPanel; public EditPanel(){ graphicsPanel = new JPanel(); } public void paintComponent(Graphics g){ graphicsPanel.revalidate(); //update the scrollpane to current panel size repaint(); Graphics g2 = graphicsPanel.getGraphics(); g2.drawImage(imageToDraw, 0, 0, null); } } }

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  • Gson serialization depending on field value

    - by Serj Lotutovici
    I have a POJO that is similar to: public class MyGsonPojo { @Expose @SerializedName("value1") private String valueOne; @Expose @SerializedName("value2") private boolean valueTwo; @Expose @SerializedName("value3") private int valueThree; // Getters and other stuff here } The issue is that this object has to be serialized into a json body for a call to the server. Some fields are optional for the request and if I even send it with default and null values, the API responds differently (Unfortunately changing the api is not an option). So basically I need to exclude fields from serialization if any of them is set to a default value. For example if the field valueOne is null the resulting json should be: { "value2" : true, "value3" : 2 } Any idea how to make this a painless effort? I wouldn't want to build the json body manually. Any help would be great. Thank you in advice.

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  • richfaces suggestionBox passing additional values to backing bean

    - by Martlark
    When using the rich faces suggestionBox how can you pass more than one id or value from the page with the text input to the suggestionBox backing bean. ie: to show a list of suggested cities within a selected state? Here is my autoComplete method. public List< Suburb > autocomplete(Object suggest) { String pref = (String) suggest; ArrayList< Suburb > result = new ArrayList< Suburb >(); Iterator< Suburb > iterator = getSuburbs().iterator(); while( iterator.hasNext() ) { Suburb elem = ((Suburb) iterator.next()); if( (elem.getName() != null && elem.getName().toLowerCase().indexOf( pref.toLowerCase() ) == 0) || "".equals( pref ) ) { result.add( elem ); } } return result; } As you can see there is one value passed from the page, Object suggest, which is the text of the h:inputText (in the faceLets m:textFormRow ) <m:textFormRow id="suburb" label="#{msgs.suburbPrompt}" property="#{bean[dto].addressDTO.suburb}" required="true" maxlength="100" size="30" /> <rich:suggestionbox height="200" width="200" usingSuggestObjects="true" suggestionAction="#{suburbsMBean.autocomplete}" var="suburb" for="suburb" fetchValue="#{suburb.name}" id="suggestion"> <h:column> <h:outputText value="#{suburb.name}" /> </h:column> </rich:suggestionbox> Earlier in the page you can select a state which I'd like to use to pare down the list of suburbs that the suggestion box displays.

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  • Calling web service from seems to hang

    - by anothershrubery
    I am trying to call an asmx web service from an Android app. Just literally started some Android development today. I've been following various solutions I have found on the net and on here and it seems it is more difficult than anticipated. I have tried various solutions and using KSoap2 seems to be the easiest way to implement this, well it would be if I could get it working. I have the following code which works up until a point: private class CallWebService extends AsyncTask<Void, Void, Void> { private static final String SOAP_ACTION = "http://tempuri.org/GetUser"; private static final String METHOD_NAME = "GetUser"; private static final String NAMESPACE = "http://tempuri.org/"; private static final String URL = "http://160.10.1.79:59315/Service1.asmx"; TextView tv; @Override protected Void doInBackground(Void... params) { tv=(TextView)findViewById(R.id.txtMessage); try { SoapObject request = new SoapObject(NAMESPACE, METHOD_NAME); SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11); envelope.dotNet=true; envelope.setOutputSoapObject(request); HttpTransportSE androidHttpTransport = new HttpTransportSE(URL); androidHttpTransport.call(SOAP_ACTION, envelope); Object result = (Object)envelope.getResponse(); tv.setText(result.toString()); } catch (Exception e) { tv.setText(e.getMessage()); } return null; } } It seems to hang at the line androidHttpTransport.call(SOAP_ACTION, envelope); Any ideas why? Is this the correct approach? Should I be looking in another direction?

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  • Use HTTP PUT to create new cache (ehCache) running on the same Tomcat?

    - by socal_javaguy
    I am trying to send a HTTP PUT (in order to create a new cache and populate it with my generated JSON) to ehCache using my webservice which is on the same local tomcat instance. Am new to RESTful Web Services and am using JDK 1.6, Tomcat 7, ehCache, and JSON. I have my POJOs defined like this: Person POJO: import javax.xml.bind.annotation.XmlRootElement; @XmlRootElement public class Person { private String firstName; private String lastName; private List<House> houses; // Getters & Setters } House POJO: import javax.xml.bind.annotation.XmlRootElement; @XmlRootElement public class House { private String address; private String city; private String state; // Getters & Setters } Using a PersonUtil class, I hardcoded the POJOs as follows: public class PersonUtil { public static Person getPerson() { Person person = new Person(); person.setFirstName("John"); person.setLastName("Doe"); List<House> houses = new ArrayList<House>(); House house = new House(); house.setAddress("1234 Elm Street"); house.setCity("Anytown"); house.setState("Maine"); houses.add(house); person.setHouses(houses); return person; } } Am able to create a JSON response per a GET request: @Path("") public class MyWebService{ @GET @Produces(MediaType.APPLICATION_JSON) public Person getPerson() { return PersonUtil.getPerson(); } } When deploying the war to tomcat and pointing the browser to http://localhost:8080/personservice/ Generated JSON: { "firstName" : "John", "lastName" : "Doe", "houses": [ { "address" : "1234 Elmstreet", "city" : "Anytown", "state" : "Maine" } ] } So far, so good, however, I have a different app which is running on the same tomcat instance (and has support for REST): http://localhost:8080/ehcache/rest/ While tomcat is running, I can issue a PUT like this: echo "Hello World" | curl -S -T - http://localhost:8080/ehcache/rest/hello/1 When I "GET" it like this: curl http://localhost:8080/ehcache/rest/hello/1 Will yield: Hello World What I need to do is create a POST which will put my entire Person generated JSON and create a new cache: http://localhost:8080/ehcache/rest/person And when I do a "GET" on this previous URL, it should look like this: { "firstName" : "John", "lastName" : "Doe", "houses": [ { "address" : "1234 Elmstreet", "city" : "Anytown", "state" : "Maine" } ] } So, far, this is what my PUT looks like: @PUT @Path("/ehcache/rest/person") @Produces(MediaType.APPLICATION_JSON) @Consumes(MediaType.APPLICATION_JSON) public Response createCache() { ResponseBuilder response = Response.ok(PersonUtil.getPerson(), MediaType.APPLICATION_JSON); return response.build(); } Question(s): (1) Is this the correct way to write the PUT? (2) What should I write inside the createCache() method to have it PUT my generated JSON into: http://localhost:8080/ehcache/rest/person (3) What would the command line CURL comment look like to use the PUT? Thanks for taking the time to read this...

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