I saw a quiete strange behavior when using Avro in a MapReduce Job. Indeed the Iterable used
is very strange : iterator.next do not point on an object but on something which change its value at each call of the function "next" !!
Example :
public static class MyAvroReducer extends AvroReducer<Long, MyAvroType,
Pair<Long, MyAvroType>> {
#Override
public void reduce(Long user, Iterable<MyAvroType> listAvroType,
AvroCollector<Pair<Long,MyAvroType>> collector,
Reporter reporter)
throws IOException {
// basically here I am expecting a list of two MyAvroType object
// The first one who has a field "type" equals to "foo" and the second
// who has a filed "type" equals to "bar"
MyAvroType foo;
MyAvroType bar;
for (MyAvroType obj : listAvroType){
if (obj.getType().equals("foo") {foo = obj;}
else if (obj.getType().equals("bar") {bar = obj;}
}
system.out.println("FOO: " + foo.getType());
system.out.println("FOO: " + bar.getType());
}
The standard output says :
FOO: bar
BAR: bar
How has been coded the Iterable here ? and why ?? Or maybe I do something wrong ?
I found your question because I had the same problem. Tests I ran seem to show that there is only one instance being returned by the Iterable for all iterations. The Iterable must be replacing the content of the same object each time it reads a new AVRO object. I ended up with a list of thousands of the last object returned. I found that, as soon as I called iterator.next(), the object I had from the previous iteration would suddenly morph into the new object.
I can sort of understand why they do it this way, as an Iterable is used to enable a limitless number of objects through processing - i.e., more than could possibly fit in memory at one time. So, they are not expecting anyone to hold onto an object after the call to iterator.next().
If you need to refer to any previous objects returned from the iterable, you'll have to copy the object into a new instance before going to the next object in the Iterable.
I used Cloner from google's cloning-1.8.5 tool to solve the problem. My objects are about five or six levels deep of nesting, but it seemed to work.
Google cloning-1.8.5
Another alternative would be to implement your own copy method on every object.
Thanks,
Vick
Related
What I was doing before was that I was calling a function of my interface and it determinate in a switch condition thanks to a parameter what to do with the data. What kind of specialization they have.
But now, what I am trying to create a local object, treat it, and then add it to my containers of the interface.
In order to do that I have to copy all the value of my local object (which have been treated) in my container of the interface.
So I created a copy_cell function in the interface, a virtual one, and one in the subclass. But whenever I try to do it the interface function is called and not the subfunction.
GridCell_voxel * local_cell;
local_cell = new GridCell_voxel(m_grid_map( cell2matindex_x(cell_index_x), cell2matindex_y(cell_index_y))->getVoxelResolution(), m_grid_map( cell2matindex_x(cell_index_x), cell2matindex_y(cell_index_y))->getVoxel().size());
local_cell->process_points(relevant_points, m_mapping_type);
//This is the line I need to change
local_cell->copy_cell (m_grid_map( cell2matindex_x( cell_index_x), cell2matindex_y( cell_index_y))) ;
Do you have any idea on the way to go? What am I missing here?
Sorry for the lack of information, i will try to expose how i managed and what i was actually looking for.
So i have a container of IntefaceCell, called m_grid_map, full of cell that has been specialized. In my case m_grid_map is full of GridCell_voxel which is a sub class from InterfaceCell.
What i want to do is, create a new local GridCell_voxel, copy the information in it. Then process the informations, then copy the local cell in the container.
The important part is the dynamic_cast in the copy cell function, which allow you to take an InterfaceCell as argument and then treat it as GridCell_voxel.
//Main.cpp
GridCell_voxel * local_cell;
local_cell = new GridCell_voxel();
local_cell->copy_cell (m_grid_map( cell2matindex_x( cell_index_x), cell2matindex_y( cell_index_y)));
local_cell->process_points(relevant_points, m_mapping_type);
m_grid_map( cell2matindex_x( cell_index_x), cell2matindex_y( cell_index_y))->copy_cell (local_cell);
delete local_cell;
//GridCell_voxel.cpp
void GridCell_voxel::copy_cell(GridCellInterface* cell) {
GridCell_voxel* voxel_cell = dynamic_cast<GridCell_voxel*>(cell);
this->m_voxel_start_height = voxel_cell->m_voxel_start_height;
this->init = true;
this->m_ground_voxel_position = voxel_cell->m_ground_voxel_position;
}
I hope it will help someone.
We have a business need to collect specific bindings in every JSF page. and we do that inside overridden ViewHandlerWrapper class
I use the below code inside renderView method to get the whole expression value property for every RichInputText and it's work fine for me
ValueExpression valExp = Inputcomponent.getValueExpression("value");
String ExpressionString = valExp.getExpressionString();
output was: #{binding.EmployeeId.inputValue}
When I do the same against RichButtin I got null value as following:
ValueExpression valExp = Btncomponent.getValueExpression("actionlistener");
String ExpressionString = valExp.getExpressionString();
What is the wrong in my last peace of code?
Obtaining a ValueExpression form a RichInputText works because, as the name suggests, it evaluates to a value, which may or may not be an EL expression, let alone a method.
On the other hand, a RichButton does not really have to evaluate to something; rather, it aims to invoke behavior (i.e. a method), from which you would want a MethodExpression - though in this case, the closest we get to it is a MethodBinding.
Luckily, UIXCommand, a superclass of RichButton, provides two methods from which you can obtain your action listeners:
public final MethodBinding getActionListener()
From the MethodBinding returned, you can invoke getExpressionString() so you can get what you wanted - such as some actionListener EL string like #{binding.bean.actionListenerMethod}.
public final ActionListener[] getActionListeners()
Might be worth mentioning, though there is not much merit for this in your use case. It simply returns the listeners on which you can manually process the events.
If a page or component class has one instance field which is a non-synchronized object, f.ex. an ArrayList, and the application has code that structurally modifies this field, should the access to this field be synchronized ?
F.ex.:
public class MyPageOrComponent
{
#Persist
private List<String> myList;
void setupRender()
{
if (this.myList == null)
{
this.myList = new ArrayList<>();
}
}
void afterRender(MarkupWriter writer)
{
// Should this be synchronized ?
if (someCondition)
{
this.myList.add(something);
}
else
{
this.myList.remove(something);
}
}
}
I'm asking because I seem to understand that Tapestry creates only one instance of a page or component class and it uses this instance for all the connected clients (but please correct me if this is not true).
In short the answer is no, you don't have to because Tapestry does this for you. Tapestry will transform your pages and classes for you at runtime in such a way that wherever you interact with your fields, they will not actually be working on the instance variable but on a managed variable that is thread safe. The full inner workings are beyond me, but a brief reference to the transformation can be found here.
One warning, don't instantiate your page/component variables at decleration. I have seen some strange behaviour around this. So don't do this:
private List<String> myList = new ArrayList<String>;
Tapestry uses some runtime byte code magic to transform your pages and components. Pages and components are singletons but the properties are transformed so that they are backed by a PerThreadValue. This means that each request gets it's own copy of the value so no synchronization is required.
As suggested by #joostschouten you should never initialize a mutable property in the field declaration. The strange behaviour he discusses is caused beacause this will be shared by all requests (since the initializer is only fired once for the page/component singleton). Mutable fields should instead be initialized in a render method (eg #SetupRender)
I am trying to add the instance of an object that I click on to a list on my control object. However when I do so it says that the reference is not set to an instance of an object. The code I have to instantiate the list on the control object is:
public List<Transform> selected = new List<Transform>();
And I tried to add to it to that list using this code attached to the unit:
if (!selected)
{
// Set selected state
selected = true;
// Add to Selected List
control.GetComponent<ForwardCommandScript>().selected.Add(this.transform);
// Set material colour brighter
oldColour = gameObject.renderer.material.color;
newColour = oldColour + new Color(0.2f, 0.2f, 0.2f);
gameObject.renderer.material.color = newColour;
}
I have tried with transform as well. Later I will try to remove it by finding a reference id that was set when the unit is instantiated so should I try to add the script instead of the object if I need to find its variables and then delete the game object attached to the script. I have tried with the GameObject, transform and the class. I wanted to use the class so I can easily access the variables. I have posted this on unity answers and forums but no one replied in the week it was up and I don't like reposting the same stuff on the same site.
Cheers, Scobbo
Your error NullReferenceException: Object reference not set to an instance of an object states that something in the associated line is null. Since the error message doesn't state which part is null, you have to split your code up and check which part is failing.
I'm not sure how you split it up, but try it this way:
var script = control.GetComponent<ForwardCommandScript>();
if (script == null) Debug.Log("script not found");
if (script.selected == null) Debug.Log("selected is null");
script.selected.Add(this.transform);
Now you should get one of the two messages in your debug log before the exception raises. Either the script was not found and you have to check if it is correctly assigned to the game object and if control is the correct game object, or selected is null which should not happen if you initialized it like you posted...
Thanks for adding the complete Error Message :)
you need to replace
control.GetComponent<ForwardCommandScript>().selected.Add(this.transform);
with
control.GetComponent<ForwardCommandScript>().selected.Add(transform);
because
this
is a reference to the script and not the GameObject. you could also use gameObject.transform which transform is just an abbreviation for
I have an object called X with a method GET_BANK, like in the picture below:
I want to call the function GET_BANK and I am trying to set the input parameter BLZ with a certain value.
I don't quite understand the data structure that is presented here and how I can access it.
At this point my code looks like this (simple version):
data: testobj type ref to ZCO_BLZSERVICE_PORT_TYPE .
data: input type ZGET_BANK .
input-BLZ = '10070000'.
I think the error that I am getting "The data object "INPUT" does not have a component called "BLZ"." is not relevant as I obviously have no idea on how to set the BLZ parameter.
Edit: Getting to BLZ can be done by chaining multiple parameters / objects:
input-PARAMETERS-BLZ = '10070000'.
As far as I can see, your input data should refer to TYPE ZGET_BANK_TYPE. Try double-clicking the field with that content in the screen you showed to see whether it leads to a structure with a component named BLZ.