Develop Reference

Copy changed fields into an object in Java

I have a method like this:
public User getUpdatedUser(UserInfo userInfo, User user) throws ProvisioningException {
if (!userInfo.getUserExternalId().equals(user.getImmutableId()) || !userInfo.getAccountExternalId().equals(
getExternalAccountId(user.getAccountid())))
throw new ProvisioningException(Response.Status.BAD_REQUEST, ProvisioningErrorCodes.INVALID_INPUT);
if (user.getEmail() != userInfo.getEmail()) user.setEmail(userInfo.getEmail());
if (user.getFirstName() != userInfo.getFirstName()) user.setFirstName(userInfo.getFirstName());
if (user.getLastName() != userInfo.getLastName()) user.setLastName(userInfo.getLastName());
if (user.getPhoneNumber() != userInfo.getPhoneNumber()) user.setPhoneNumber(userInfo.getPhoneNumber());
if (user.getCompany() != userInfo.getCompany()) user.setCompany(userInfo.getEmail());
if (user.getJobTitle() != userInfo.getJobTitle()) user.setJobTitle(userInfo.getJobTitle());
if (user.getStatus() != ApiUtils.changeEnumClass(userInfo.getStatus(), DbConstants.UserStatus.class))
user.setStatus(ApiUtils.changeEnumClass(userInfo.getStatus(), DbConstants.UserStatus.class));
if (user.getAccountAdministratorInternalUse() != isAccountAdmin(userInfo.getRoles()))
user.setAccountAdministratorInternalUse(isAccountAdmin(userInfo.getRoles()));
if (user.getPodAdministratorInternalUse() != isPodAdmin(userInfo.getRoles()))
user.setPodAdministratorInternalUse(isPodAdmin(userInfo.getRoles()));
return user;
}
Basically, copying only those fields into user which are different. Is there a neater/cleaner way to do this in Java instead of all the if conditions?

Please, consider the use of JaVers.
The library will allow you mainly to compute diffs that you can apply latter in your objects.
You can take a different approach and use a mapper library, like Mapstruct.
After installing the required dependencies, define a Mapper interface, something like:
import org.mapstruct.Mapper;
import org.mapstruct.Mapping;
import org.mapstruct.MappingTarget;
import org.mapstruct.factory.Mappers;
#Mapper
public interface UserMapper {
UserMapper INSTANCE = Mappers.getMapper(UserMapper.class);
void update(UserInfo userInfo, #MappingTarget User user);
}
And use it to update the properties in the target object:
UserMapper.INSTANCE.update(userInfo, user);
The library will take care of map every property in the destination object. You can tweak the mapping process as appropriate.
A lot of more elaborated, but if your information is JSON you can apply a merge patch operation over the destination object with the received JSON information. Please, review this excellent article, it is focused on Spring, but it will provide you a great background about the proposed solution.
Finally, you can follow a simpler approach and use Apache Commons BeanUtils and copyProperties between your objects.
Please, be aware that with the exception of the first solution based on JaVers, the rest of the proposed approaches will copy all properties from the source to the destination object, not only the different ones. Unless for the possible performance overhead or any unindicated side effect, this fact will make no difference in the result obtained.
Alternative approach, use it with responsability.
Manual mode (reflection).
//user is the User instance you wish to modify
Class<User> rfkClass = User.class;
Field field = rfkClass.getDeclaredField("name"); //private final? Who cares
field.setAccessible(true);
field.set(user, "TheDestroyer");
field = rfkClass.getDeclaredField("email");
field.setAccessible(true);
field.set(user, "chuck#norris.com");
//... your changes here
// return user; --> same instance, now modified internally
Regardless the variables were declared as final, private, whatever, reflection just doesn't care.

You could define an API by which both objects abide, and then use reflection to create a generic method.
interface User {
void setFoo(String foo);
String getFoo();
}
class UserImpl implements User { ... }
class UserInfo implements User { ... }
public class Mirrorer<T> {
private final String[] methodNames;
private final MethodHandle[] methodHandles;
public Mirrorer(Class<T> interfaceClass) {
if (!interfaceClass.isInterface()) {
throw new IllegalArgumentException("interfaceClass must be an interface.");
}
Method[] methods = interfaceClass.getDeclaredMethods();
int methodsCount = methods.length;
methodNames = new String[methodsCount];
methodHandles = new MethodHandle[methodsCount];
MethodHandles.Lookup lookup = MethodHandles.lookup();
try {
for (int i = 0; i < methodsCount; i++) {
Method method = methods[i];
methodNames[i] = method.getName();
methodHandles[i] = lookup.unreflect(method);
}
} catch (IllegalAccessException e) {
throw new AssertionError();
}
}
public void mirror(T from, T to) throws Throwable {
for (int i = 0; i < methodNames.length; i++) {
String methodName = methodNames[i];
if (methodName.startsWith("get")) {
MethodHandle methodHandle = methodHandles[i];
Object fromValue = methodHandle.invoke(from);
Object toValue = methodHandle.invoke(to);
if (!Objects.equals(fromValue, toValue)) {
MethodHandle setter = getSetter(methodName.substring(3), methodHandle.type().returnType());
setter.invoke(to, fromValue);
}
}
}
}
private MethodHandle getSetter(String field, Class<?> type) {
for (int i = 0; i < methodNames.length; i++) {
String methodName = methodNames[i];
if (methodName.equals("set" + field)) {
MethodHandle methodHandle = methodHandles[i];
MethodType methodType = methodHandle.type();
if (methodType.parameterCount() != 0 && methodType.parameterType(0).equals(type)) {
return methodHandle;
}
}
}
throw new AssertionError();
}
}
Mirrorer<User> mirrorer = new Mirrorer<>(User.class);
UserInfo userInfo = ...
UserImpl user = ...
mirrorer.mirror(userInfo, user);

Looks like you just copy all different fields from userInfo to user and you are able not to compare all the valuse, just set it all together.
public User getUpdatedUser(UserInfo userInfo, User user) throws ProvisioningException {
if (!userInfo.getUserExternalId().equals(user.getImmutableId())
|| !userInfo.getAccountExternalId().equals(getExternalAccountId(user.getAccountid())))
throw new ProvisioningException(Response.Status.BAD_REQUEST, ProvisioningErrorCodes.INVALID_INPUT);
user.setEmail(userInfo.getEmail());
user.setFirstName(userInfo.getFirstName());
user.setLastName(userInfo.getLastName());
user.setPhoneNumber(userInfo.getPhoneNumber());
user.setCompany(userInfo.getEmail());
user.setJobTitle(userInfo.getJobTitle());
user.setStatus(userInfo.getStatus());
user.setAccountAdministratorInternalUse(isAccountAdmin(userInfo.getRoles()));
user.setPodAdministratorInternalUse(isPodAdmin(userInfo.getRoles()));
return user;
}

Passing a second argument to Guava Cache load() method

I've previously asked a question on here on how to implement Guava Cache in Java, seen here. While it has worked, I've recently noticed a bug in the getAllProfile method.
private LoadingCache<Integer, List<Profile>> loadingCache = CacheBuilder.newBuilder()
.refreshAfterWrite(10,TimeUnit.MINUTES)
.maximumSize(100).build(
new CacheLoader<Integer, List<Profile>>() {
#Override
public List<Profile> load(Integer integer) throws Exception {
Profile profile= new Profile();
if (integer == null) {
integer = 10;
}
return profileDAO.getAllProfiles(profile, integer);
}
}
);
public List<Profile> getAllProfiles(Profile profile, Integer integer) throws Exception {
return loadingCache.get(integer);
}
In the method, I'm passing in a Profile object called profile. This is so that on the Service layer, the user can set a parameter for the profiles of workers, to see if they are still employed, using #QueryParam:
#GET
public List<Profile> getProfiles(#QueryParam("employed") Boolean employed, #QueryParam("size") Integer integer) {
//code for service here. the value for query param is used in a
//new Profile object
}
The profile object created here is passed down through the manager tier, and into the DAO tier, where the parameters set in it, like the boolean employed, are parsed into arguments for a select statement.
The issue here is that since I've started using the cache, the boolean is no longer being parsed. calling the method with a System.out.println to evaluate the employed field evaluates as null. This makes sense, as I create a new Profile object in the cache manager, with no setters called, in addition to the cache get method not taking profile at the getAllProfile method; it only takes size.
I thought I could get around this by adding in a new Profile parameter in the load method, like so:
private LoadingCache<Integer, List<Profile>> loadingCache = CacheBuilder.newBuilder()
.refreshAfterWrite(10,TimeUnit.MINUTES)
.maximumSize(100).build(
new CacheLoader<Integer, List<Profile>>() {
#Override
public List<Profile> load(Integer integer) throws Exception {
#Override
public List<Profile> load(Integer integer, Profile profile) throws Exception {
if (integer == null) {
integer = 10;
}
return profileDAO.getAllProfiles(profile, integer);
}
}
}
);
However, load() appears to be designed only to take one argument, so this brings up this error:
Class 'Anonymous class derived from CacheLoader' must either be declared abstract or implement abstract method 'load(K)' in 'CacheLoader'
To reiterate, all I need to do is pass the profile object created in Service layer to the manager layer and cache. This seems to be as simple as passing a second argument to load(), but that does not seem to be possible.
EDIT:
I've edited the getAllProfiles method to use Callable:
public List<Profile> getAllProfiles(Profile profile, Integer integer) throws Exception {
return loadingCache.get(size, new Callable<Profile>() {
#Override
public Profile call() throws Exception {
return profile;
}
});
}
This produces an error on the fact that I'm passing in Profile instead of List<Profile>. I need to pass in profile, though, so I can parse through the fields in the DAO for the SQL statement.

Here is an example:
public class ImageCache2 extends CaffeineCache<URL, Image> {
ImageCache2() {
this.cache = Caffeine.newBuilder()
.maximumSize(300)
.expireAfterWrite(5, TimeUnit.MINUTES)
.refreshAfterWrite(1, TimeUnit.MINUTES)
.build((k) -> null);
}
}
just give build a null return because we don't use it.
public static Image LoadImageFromURL(URL url, double w, double h) {
URLConnection conn;
Image returnImage;
try {
conn = url.openConnection();
} catch (IOException e1) {
e1.printStackTrace();
return null;
}
conn.setRequestProperty("User-Agent", "Wget/1.13.4 (linux-gnu)");
try (InputStream stream = conn.getInputStream()) {
returnImage = new Image(stream, w, h, true, true);
} catch (IOException e2) {
e2.printStackTrace();
return null;
}
return returnImage;
}
here is the code I really use to get the item.
public static void useExecutors(Runnable run) {
executorServices.execute(run);
}
public void LoadImage(URL url, double w, double h, Consumer<Image> callWhenFinish) {
useExecutors(() ->
{
Image thumbImage = ImageCacheInstance.Cache().get(url, (u) -> LoadImageFromURL(url, w, h));
Platform.runLater(() ->
{
callWhenFinish.accept(thumbImage);
System.out.println("ImageLoad >> Finish -- " + this);
});
});
}
here is where I call the cache get method. PS: useExecutors run it in a background thread

Passing values from database in "allowableValues"?

I am using Swagger version 2 with Java Spring. I have declared a property and it works fine and it generates a drop down list of value I assigned.
#ApiParam(value = "Pass any one Shuttle provider ID from the list", allowableValues = "1,2,3,4,10")
private Long hotelId;
Now, I need a way to populate this list which is passed in allowableValues from my database as it could be random list as well as huge data. How can I assign list of values dynamically from database in this allowableValues?

This question is bit old, I too faced the same problem so thought of adding here which may help some one.
//For ApiModelProperty
#ApiModelProperty(required = true, allowableValues = "dynamicEnum(AddressType)")
#JsonProperty("type")
private String type;
Created a component which implements ModelPropertyBuilderPlugin
#Component
#Order(SwaggerPluginSupport.SWAGGER_PLUGIN_ORDER + 1)
public class ApiModelPropertyPropertyBuilderCustom implements ModelPropertyBuilderPlugin {
private final DescriptionResolver descriptions;
#Autowired
public ApiModelPropertyPropertyBuilderCustom(DescriptionResolver descriptions) {
this.descriptions = descriptions;
}
public void apply(ModelPropertyContext context) {
try {
AllowableListValues allowableListValues = (AllowableListValues) FieldUtils.readField(context.getBuilder(),
"allowableValues", true);
if(allowableListValues!=null) {
String allowableValuesString = allowableListValues.getValues().get(0);
if (allowableValuesString.contains("dynamicEnum")) {
String yourOwnStringOrDatabaseTable = allowableValuesString.substring(allowableValuesString.indexOf("(")+1, allowableValuesString.indexOf(")"));
//Logic to Generate dynamic values and create a list out of it and then create AllowableListValues object
context.getBuilder().allowableValues(allowableValues);
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
public boolean supports(DocumentationType delimiter) {
return SwaggerPluginSupport.pluginDoesApply(delimiter);
}
}
Similary for ApiParam we can create component which will implement ParameterBuilderPlugin
#Override
public void apply(ParameterContext context) {
#SuppressWarnings("Guava") final Optional<ApiParam> apiParam =
context.resolvedMethodParameter().findAnnotation(ApiParam.class);
if (apiParam.isPresent()) {
final String allowableValuesString = apiParam.get().allowableValues();
//Your logic here
context.parameterBuilder().allowableValues(allowableValues);
}
}

You need to create constructor in SwaggerConfiguration class.
#Autowire service and withdraw data you need from database
assign this to final variable
assign this final variable to allowableValues in annotation
enjoy not efficient api
private final String allowableValues;
public SwaggerConfiguration() {
List<YourEntitiy> list = someService.findAll();
//code to get every value you need and add create comma separated String
StringJoiner stringJoiner = new StringJoiner(",");
stringJoiner.add(list.get(0).getValue());
this.allowableValues = stringJoiner.toString();
}
#ApiParam(allowableValues = allowableValues)
But I think it's bad idea getting all ids from database just to create allowable values. Just validate in api method if that id exist and/or Create new api to get ids from database, use pagination from Spring Data project, like PageImpl<> javadocs

how to pass object parameters in command?

I created an eclipse-rcp's project's plugin.xml with a new command with a parameter.
ArrayList<parameterization> parameters = new ArrayList<parameterization>();
IParameter iparam;
//get the command from plugin.xml
IWorkbenchWindow window = PlatformUI.getWorkbench().getActiveWorkbenchWindow();
ICommandService cmdService = (ICommandService)window.getService(ICommandService.class);
Command cmd = cmdService.getCommand("org.ipiel.demo.commands.click");
//get the parameter
iparam = cmd.getParameter("org.ipiel.demo.commands.click.paramenter1");
Parameterization params = new Parameterization(iparam, "commandValue");
parameters.add(params);
//build the parameterized command
ParameterizedCommand pc = new ParameterizedCommand(cmd, parameters.toArray(new Parameterization[parameters.size()]));
//execute the command
IHandlerService handlerService = (IHandlerService)window.getService(IHandlerService.class);
handlerService.executeCommand(pc, null);
I tried this example to pass parameters and it worked.
The issue in this example that I could pass only parameters of type String. ( because Parameterization )
I want to pass parameter of hash map and in general to pass any object.
I tried this code
IServiceLocator serviceLocator = PlatformUI.getWorkbench();
ICommandService commandService = (ICommandService) serviceLocator.getService(ICommandService.class);
ExecutionEvent executionEvent = new ExecutionEvent(cmd, paramArray, null, null);
cmd.executeWithChecks(executionEvent);
but it didn't work the parameters didn't move ( it was null)
Could you please help to to move object as parameter in command ?

Since it would get confusing to add another solution to my first answer, I'll provide another one for a second solution.
The choices I gave were " A) use the selected object of the "Execution Event" (examine that, it contains a lot of infos). B) you can use AbstractSourceProvider, so you can pass your object to the application context."
A) can be used in your Handler if your object is the selection of a Structured Object like a Tree:
MyObject p = (MyObject) ((IStructuredSelection) HandlerUtil.getCurrentSelection(event)).getFirstElement();
B) The usage of a Source provider is a bit more tricky. The main idea is, that you add your object to the application context. The important snippets for Eclipse 3.x from a project that I set up after I read this blog (note: it is in german and the example it provides doesn't work):
In your plugin.xml add:
<extension point="org.eclipse.ui.services">
<sourceProvider
provider="com.voo.example.sourceprovider.PersonSourceProvider">
<variable
name="com.voo.example.sourceprovider.currentPerson"
priorityLevel="activePartId">
</variable>
</sourceProvider>
Set up your own SourceProvider. Calling the "getCurrentState" you can get the variable (your Person object in this case) of that SourceProvider:
public class PersonSourceProvider extends AbstractSourceProvider{
/** This is the variable that is used as reference to the SourceProvider
*/
public static final String PERSON_ID = "com.voo.example.sourceprovider.currentPerson";
private Person currentPerson;
public PersonSourceProvider() {
}
#Override
public void dispose() {
currentPerson = null;
}
**/**
* Used to get the Status of the source from the framework
*/
#Override
public Map<String, Person> getCurrentState() {
Map<String, Person> personMap = new HashMap<String, Person>();
personMap.put(PERSON_ID, currentPerson);
return personMap;
}**
#Override
public String[] getProvidedSourceNames() {
return new String[]{PERSON_ID};
}
public void personChanged(Person p){
if (this.currentPerson != null && this.currentPerson.equals(p)){
return;
}
this.currentPerson = p;
fireSourceChanged(ISources.ACTIVE_PART_ID, PERSON_ID, this.currentPerson);
}
}
In your View you register to the SourceProvider and set the Object to the object you want to transfer to your Handler.
public void createPartControl(Composite parent) {
viewer = new TreeViewer(parent);
viewer.setLabelProvider(new ViewLabelProvider());
viewer.setContentProvider(new ViewContentProvider());
viewer.setInput(rootPerson);
getSite().setSelectionProvider(viewer);
viewer.addSelectionChangedListener(new ISelectionChangedListener() {
#Override
public void selectionChanged(SelectionChangedEvent event) {
Person p = null;
if (event.getSelection() instanceof TreeSelection) {
TreeSelection selection = (TreeSelection) event.getSelection();
if (selection.getFirstElement() instanceof Person) {
p = (Person) selection.getFirstElement();
}
}
if (p==null) {
return;
}
IWorkbenchWindow window = PlatformUI.getWorkbench().getActiveWorkbenchWindow();
ISourceProviderService service = (ISourceProviderService) window.getService(ISourceProviderService.class);
PersonSourceProvider sourceProvider = (PersonSourceProvider) service.getSourceProvider(PersonSourceProvider.PERSON_ID);
sourceProvider.personChanged(p);
}
});
}
And in your Handler you can just call the PersonSourceProvider#getCurrentState to get your Objects back.
Advantage of this method is, that you can use the Objectd anywhere you want. E.g. you can even set up a PropertyTester to enable/disable UI elements according to the currently selected Object.

The Parameterized Command does only accept Strings.
Here is an example for smaller objects:
Disclaimer: this is for Eclipse 3.x. I am not using Eclipse 4.x a lot, so you might have to adapt there in case you need it.
Create a Pluginproject (com.voo.example.commandparameter.advanced) with a View (com.voo.example.commandparameter.advanced.view) , a Command (com.voo.example.commandparameter.advanced.sysoCommand) with menu entry and Handler(com.voo.example.commandparameter.advanced.sysoCommand), and a universal Object (MyTestObject).
The Command needs a Parameter and a Parametertype in the plugin.xml, that gets passed to it:
<extension
point="org.eclipse.ui.commands">
<command
id="com.voo.example.commandparameter.advanced.sysoCommand"
name="SysoCommand">
<commandParameter
id="myObject"
name="object"
optional="true"
typeId="com.voo.example.commandparameter.advanced.testType">
</commandParameter>
</command>
<commandParameterType
id="com.voo.example.commandparameter.advanced.testType"
type="com.voo.example.commandparameter.advanced.MyTestObject">
</commandParameterType>
In the Object you set atrtibutes like name and street and define a convertToString method like that:
public String convertToString() {
return getName() +",,,"+ getStreet();
}
(you can override the toString method, too. I just used that method to set weired delimiters to the returned String)
And in a Class MyParamterConverter you can transfer it back:
public class MyParameterConverter extends AbstractParameterValueConverter {
public MyParameterConverter() {
}
#Override
public String convertToString(Object parameterValue)
throws ParameterValueConversionException {
return parameterValue.toString();
}
/**
* This will always create a new object. Just keep that in mind
* if you're trying to work with the objects.
*/
#Override
public Object convertToObject(String parameterValue)
throws ParameterValueConversionException {
//Split the String to get the attributes back
String delimiter =",,,";
String[] split = parameterValue.split(delimiter);
String name = split[0];
String street = split [1];
return new MyTestObject(name, street);
}
}
Now you can call the command with a buttonclick in your view, for example:
btnGo.addSelectionListener(new SelectionAdapter() {
#Override
public void widgetSelected(SelectionEvent event) {
MyTestObject testObject = new MyTestObject(textName.getText(),textStreet.getText());
ICommandService cS = (ICommandService)getSite().getService(ICommandService.class);
IHandlerService hS = (IHandlerService)getSite().getService(IHandlerService.class);
Command sysoComm = cS.getCommand("com.voo.example.commandparameter.advanced.sysoCommand");
HashMap<String, String> params = new HashMap<String, String>();
params.put("myObject", testObject.convertToString());
ParameterizedCommand pC = ParameterizedCommand.generateCommand(sysoComm, params);
try {
hS.executeCommand(pC, null);
} catch (Exception e) {
e.printStackTrace();
}
}
});
And the Handler can transform the passed parameters back :
public class MyObjectHandler extends AbstractHandler {
#Override
public Object execute(ExecutionEvent event) throws ExecutionException {
String param1 = event.getParameter("myObject");
MyParameterConverter converter = new MyParameterConverter();
Object convertToObject = null;
try {
convertToObject = converter.convertToObject(param1);
} catch (ParameterValueConversionException e) {
e.printStackTrace();
}
if (convertToObject instanceof MyTestObject) {
MyTestObject to = (MyTestObject) convertToObject;
System.out.println(to.toString());
}
return null;
}
}
This should work for most smaller sized objects that do not change while you pass them. If you need to pass bigger objects, you will have two choices: A) use the selected object of the "Execution Event" (examine that, it contains a lot of infos). B) you can use AbstractSourceProvider, so you can pass your object to the application context.

For a long time I have been focused on delivering an object via a command parameter. But in the end, the easiest workaround is to simply ignore the parameter stuff and put the desired object in a new child IExclipseContext and execute the command with that context. That way your handler gets your object injected.
Caller:
ECommandService commandService = // get commandService...
EHandlerService handlerService = // get handlerService...
IEclipseContext context = // get active or application context...
IEclipseContext childCtx = context.createChild();
childCtx.set(MyObject.class, instancOfMyObject);
ParameterizedCommand command = commandService.createCommand("my.command.id", null);
handlerService.executeHandler(command, childCtx);
In your handler:
#Execute
public void execute(#Optional MyObject myObject) {
if(myObject != null) {
// work with your object
}
}
Voila, no converters or callbacks (i.e. SelectionService) needed...

I am not really familiar with this as passing parameters to commands is quite rare. It looks like you have to use commandParameterType in the org.eclipse.ui.commands command definition to define code based on AbstractParameterValueConverter to convert between objects and the string for the parameter value.

Setting outer variable from anonymous inner class

Is there any way to access caller-scoped variables from an anonymous inner class in Java?
Here's the sample code to understand what I need:
public Long getNumber(final String type, final String refNumber, final Long year) throws ServiceException {
Long result = null;
try {
Session session = PersistenceHelper.getSession();
session.doWork(new Work() {
public void execute(Connection conn) throws SQLException {
CallableStatement st = conn.prepareCall("{ CALL PACKAGE.procedure(?, ?, ?, ?) }");
st.setString(1, type);
st.setString(2, refNumber);
st.setLong(3, year);
st.registerOutParameter(4, OracleTypes.NUMBER);
st.execute();
result = st.getLong(4) ;
}
});
} catch (Exception e) {
log.error(e);
}
return result;
}
The code is in a DAO service class. Obviously it doesn't compile, because it asks that result be final, if it is -- it doesn't compile because I try to modify a final var. I'm bound to JDK5. Other than dropping the doWork() altogether, is there a way to set the result value from within doWork()?

Java doesn't know that doWork is going to be synchronous and that the stack frame that result is in will still be there. You need to alter something that isn't in the stack.
I think this would work
final Long[] result = new Long[1];
and then
result[0] = st.getLong(4);
in execute(). At the end, you need to return result[0];
You might want to make a class because you don't like how it looks to use an array here, but this is the basic idea.

This situation arises a lot in Java, and the cleanest way to handle it is with a simple value container class. It's the same type thing as the array approach, but it's cleaner IMO.
public class ValContainer<T> {
private T val;
public ValContainer() {
}
public ValContainer(T v) {
this.val = v;
}
public T getVal() {
return val;
}
public void setVal(T val) {
this.val = val;
}
}

You need a 'container' to hold your value. You, however, do not have to create a container class. You may use classes in the java.util.concurrent.atomic package. They provide an immutable wrapper for a value along with a set and a get method. You have AtomicInteger, AtomicBoolean, AtomicReference<V> (for your objects) e.t.c
In the outer method:
final AtomicLong resultHolder = new AtomicLong();
In the anonymous inner class method
long result = getMyLongValue();
resultHolder.set(result);
Later in your outer method
return resultHolder.get();
Here's an example.
public Long getNumber() {
final AtomicLong resultHolder = new AtomicLong();
Session session = new Session();
session.doWork(new Work() {
public void execute() {
//Inside anonymous inner class
long result = getMyLongValue();
resultHolder.set(result);
}
});
return resultHolder.get(); //Returns the value of result
}

Long is immutable. If you use a mutable class, holding a long value, you can change the value. For example:
public class Main {
public static void main( String[] args ) throws Exception {
Main a = new Main();
System.out.println( a.getNumber() );
}
public void doWork( Work work ) {
work.doWork();
}
public Long getNumber() {
final LongHolder result = new LongHolder();
doWork( new Work() {
public void doWork() {
result.value = 1L;
}
} );
return result.value;
}
private static class LongHolder {
public Long value;
}
private static abstract class Work {
public abstract void doWork();
}
}

If the containing class is MyClass -->
MyClass.this.variable = value;
Do not remember if this would work with a private variable (I think it would work).
Only works for attributes of the class (class variable). Does not work for method local variables. In JSE 7 probably there will be closures to do that kind of thing.

Anonymous classes/methods are not closures - this is exactly the difference.
The problem is that doWork() could create a new thread to call execute() and getNumber() could return before the result is set - and even more problematically: where should execute() write the result when the stack frame that contains the variable is gone? Languages with closures have to introduce a mechanism to keep such variables alive outside their original scope (or ensure that the closure is not executed in a separate thread).
A workaround:
Long[] result = new Long[1];
...
result[0] = st.getLong(4) ;
...
return result[0];

The standard solution to this is to return a value. See, for instance, ye olde java.security.AccessController.doPrivileged.
So the code would look something like this:
public Long getNumber(
final String type, final String refNumber, final Long year
) throws ServiceException {
try {
Session session = PersistenceHelper.getSession();
return session.doWork(new Work<Long>() {
public Long execute(Connection conn) throws SQLException {
CallableStatement st = conn.prepareCall("{ CALL PACKAGE.procedure(?, ?, ?, ?) }");
try {
st.setString(1, type);
st.setString(2, refNumber);
st.setLong(3, year);
st.registerOutParameter(4, OracleTypes.NUMBER);
st.execute();
return st.getLong(4);
} finally {
st.close();
}
}
});
} catch (Exception e) {
throw ServiceException(e);
}
}
(Also fixed the potential resource leak, and returning null for any error.)
Update: So apparently Work is from a third-party library and can't be altered. So I suggest not using it, at least isolate your application from so that you are not using it directly. Something like:
public interface WithConnection<T> {
T execute(Connection connnection) throws SQLException;
}
public class SessionWrapper {
private final Session session;
public SessionWrapper(Session session) {
session = nonnull(session);
}
public <T> T withConnection(final WithConnection<T> task) throws Service Exception {
nonnull(task);
return new Work() {
T result;
{
session.doWork(this);
}
public void execute(Connection connection) throws SQLException {
result = task.execute(connection);
}
}.result;
}
}

As of Hibernate 4, the method Session#doReturningWork(ReturningWork<T> work) will return the return val from the inner method:
public Long getNumber(final String type, final String refNumber, final Long year) throws ServiceException {
try {
Session session = PersistenceHelper.getSession();
return session.doReturningWork(conn -> {
CallableStatement st = conn.prepareCall("{ CALL PACKAGE.procedure(?, ?, ?, ?) }");
st.setString(1, type);
st.setString(2, refNumber);
st.setLong(3, year);
st.registerOutParameter(4, OracleTypes.NUMBER);
st.execute();
return st.getLong(4);
});
} catch (Exception e) {
log.error(e);
}
return null;
}
(Cleaned up using a Java 8 lambda)

Using AtomicLong helped me in a very similar situation and the code looked clean.
// Create a new final AtomicLong variable with the initial value 0.
final AtomicLong YOUR_VARIABLE = new AtomicLong(0);
...
// set long value to the variable within inner class
YOUR_VARIABLE.set(LONG_VALUE);
...
// get the value even outside the inner class
YOUR_VARIABLE.get();