For the evaluation of my uimaFIT-pipeline I want to build up a list of JCas instances that were annotated by the pipeline and written to xmi-files. In my evaluation I read in the xmi-files and want to access the JCas for each xmi-file and save it in a list in order to process them further.
JCasIterable goldIterable = SimplePipeline.iteratePipeline(xmiReaderGold);
JCasIterator goldIterator = goldIterable.iterator();
ArrayList<JCas> goldJCasList = new ArrayList<JCas>();
while (goldIterator.hasNext()) {
JCas goldJCas = goldIterator.next().getCas().getJCas();
goldJCasList.add(goldJCas);
}
The problem is that in every iteration of the while-loop the JCas in the list that has been added in the iteration before gets overwritten by the current JCas. How do I avoid this and how can I correctly build up my list? I tried to create a new JCas-object with JCas goldJCas = JCasFactory.createJCas() before calling next() on the iterator and adding the JCas to the list. But still I get the same result.
The JCas instance returned by iteratePipeline is always the same one - it is re-used. This is for performance reasons.
If you want to have a list of JCas-es you can do that somewhat like this
CollectionReader reader = CollectionReaderFactory.createReader(MyReader.class, <parameters>);
List<JCas> documents = new ArrayList<>();
while (reader.hasNext()) {
JCas document = JCasFactory.createJCas();
reader.getNext(document.getCas());
documents.add(document);
}
Related
In NatTable I am adding a row in filtered table. After removing the filter, the newly added row moves to last position in the table.
But I want to it to stay in the same position, that is next to the row which I added when the table is filtered.
I am currently using the RowInsertCommand. I don't want to add row via model or list which used to populated the table. I want to achieve only via NatTable commands. Is it possible?
It is always hard to follow the explanations and the issue without example code. But I assume you simply copied code from the NatTable examples, so I will explain your issue based on that.
First, the RowInsertCommand has several constructors. If you are using a constructor without a rowIndex or rowPositionparameter, the new object will ALWAYS be added at the end of the list.
When using the filter functionality in NatTable with GlazedLists, the list that is wrapped in the body DataLayer is the FilterList. If you are operating on the FilterList for calculating the rowIndex where the new object should be added and have the FilterList as base list in the RowInsertCommandHandler, the place where the new object is added is transformed between the FilterList and the base EventList, which might not be the desired result.
To solve this you need to create the RowInsertCommandHandler by using the base EventList.
EventList<T> eventList = GlazedLists.eventList(values);
TransformedList<T, T> rowObjectsGlazedList = GlazedLists.threadSafeList(eventList);
SortedList<T> sortedList = new SortedList<>(rowObjectsGlazedList, null);
this.filterList = new FilterList<>(sortedList);
this.baseList = eventList;
bodyDataLayer.registerCommandHandler(new RowInsertCommandHandler<>(this.baseList));
The action that performs the add operation then of course needs to calculate the index based on the base EventList. The following code is part of the SelectionAdapter of an IMenuItemProvider:
int rowPosition = MenuItemProviders.getNatEventData(event).getRowPosition();
int rowIndex = natTable.getRowIndexByPosition(rowPosition);
Object relative = bodyLayerStack.filterList.get(rowIndex);
int baseIndex = bodyLayerStack.baseList.indexOf(relative);
Object newObject = new ...;
natTable.doCommand(new RowInsertCommand<>(baseIndex + 1, newObject));
I am new in the reactive programming world. I am currently working in a Java reactive application using the Mutiny library.
I need to develop a loop that waits for the previous iteration to finish in order to start the next one. For instance:
List<Uni<T>> uniList = new ArrayList<>();
for (T item : items) { //items is an already fulfilled collection
uniList.add(this.doSomethingAndReturnInUni(item));
}
return Uni.combine().all().unis(uniList).combinedWith(unisToCombine -> {
List<T> list = new ArrayList<>();
unisToCombine.forEach(x ->list.add(x));
return list;
});
The for loop in the example, generates a thread per iteration. I am wondering how to order the i-th call to the method doSomethingAndReturnInUni() waits for the (i-1) call to trigger the event, that is, make the for loop sequentially. It is possible to suscribe those events in such a way?
Could you try something like this?
Builder<Item> items = Uni.join().builder();
for (Item item : items) {
builder.add(this.doSomethingAndReturnInUni(item));
}
return builder.joinAll().andCollectFailures()
.flatMap(itemList -> do whatever you need ...) //itemList type is List<Item>
I don't know why you are using uni, as this should just handle one operation, for loops you should use multi, where you can handle the back pressure, and only get the next event, when one event is finished. Multi can be run sequentially and in parallel.
see https://quarkus.io/blog/mutiny-back-pressure/
I’ve done the same, using Multi’s see the ‘generateData()’ method here:
https://github.com/Serkan80/quarkus-quickstarts/blob/development/redis-streams-quickstart/weather-producer/src/main/java/org/acme/redis/streams/producer/ValuesGenerator.java
I'm trying to produce a runtime table. Below class and codes are simplified version of my final purpose.
class AppModel {
int appID;
String appName;
AppModel({this.appID, this.appName});
}
I'm calculating, fetching some another data and trying to fill the following object like this:
// _newApps value is between 1-30 mostly but not limited
List<AppModel> theList = [];
for (int i = 0; i < _newApps; i++) {
AppModel _newRecord = AppModel();
_newRecord.appID = _getNewAppID();
_newRecord.appName = _getNewAppName();
theList.add(_newRecord);
}
So the question is the code creates a new AppModel instance for only adding the element to the list for every iteration inside the for loop. According to my program logic, this event can be repeated 100-150 times sometimes.
Is it normal or is there any more memory efficient way to do so?
Thank you in advance.
I would like to point out (a better approach) that instead of for Loop you could have used the map method on the Apps List you have. And instead of creating a object every time in the Loop create a constructor for returning the object instance using the required details.
Hope you find it useful.
Encountering a problem whereby I am specifying Private Constants at the start of a scala step definiton file which relies on a List Buffer element to be populated, however when compiling I get a 'IndexOutOfBoundsException' because the list is empty initially and only gets populated later in a for loop.
For Example I have the following 2 constants:
private val ConstantVal1= globalExampleList(2)
private val ConstantVal2= globalExampleList(3)
globalExampleList is populated further down in the file using a for loop:
for (i <- 1 to numberOfW) {
globalExampleList += x.xy }
This List Buffer adds as many values as required to a global mutable ListBuffer.
Is there a better way to declare these constants? I've tried to declare them after the for loop but then other methods are not able to access these. I have around 4 different methods within the same file which use these values and instead of accessing it via index each time i thought it would be better to declare them as a constant to keep it neat and efficient for whenever they require changing.
Thanks
You can create list buffer of necessary size with default value and populate it later:
val globalExampleList: ListBuffer[Int] = ListBuffer.fill(numberOfW)(0)
for (i <- 0 until numberOfW) {
globalExampleList(i) = x.xy
}
But ConstantVal1, ConstantVal2 will still have original default value. So you can make them vars and re-assign them after you populate the buffer.
Your code seems to have a lot of mutations and side effects.
You have 2 ways to go.
First you can use lazy modifier
private lazy val ConstantVal1= globalExampleList(2)
private lazy val ConstantVal2= globalExampleList(3)
Or you can write the two lines after the for loop.
val globalExampleList = XXXX
for (i <- 1 to numberOfW) { globalExampleList += x.xy }
private val ConstantVal1= globalExampleList(2)
private val ConstantVal2= globalExampleList(3)
I have a very simple mapping function called "BuildEntity" that does the usual boring "left/right" coding required to dump my reader data into my domain object. (shown below) My question is this - If I don't bring back every column in this mapping as is, I get the "System.IndexOutOfRangeException" exception and wanted to know if ado.net had anything to correct this so I don't need to bring back every column with each call into SQL ...
What I'm really looking for is something like "IsValidColumn" so I can keep this 1 mapping function throughout my DataAccess class with all the left/right mappings defined - and have it work even when a sproc doesn't return every column listed ...
Using reader As SqlDataReader = cmd.ExecuteReader()
Dim product As Product
While reader.Read()
product = New Product()
product.ID = Convert.ToInt32(reader("ProductID"))
product.SupplierID = Convert.ToInt32(reader("SupplierID"))
product.CategoryID = Convert.ToInt32(reader("CategoryID"))
product.ProductName = Convert.ToString(reader("ProductName"))
product.QuantityPerUnit = Convert.ToString(reader("QuantityPerUnit"))
product.UnitPrice = Convert.ToDouble(reader("UnitPrice"))
product.UnitsInStock = Convert.ToInt32(reader("UnitsInStock"))
product.UnitsOnOrder = Convert.ToInt32(reader("UnitsOnOrder"))
product.ReorderLevel = Convert.ToInt32(reader("ReorderLevel"))
productList.Add(product)
End While
Also check out this extension method I wrote for use on data commands:
public static void Fill<T>(this IDbCommand cmd,
IList<T> list, Func<IDataReader, T> rowConverter)
{
using (var rdr = cmd.ExecuteReader())
{
while (rdr.Read())
{
list.Add(rowConverter(rdr));
}
}
}
You can use it like this:
cmd.Fill(products, r => r.GetProduct());
Where "products" is the IList<Product> you want to populate, and "GetProduct" contains the logic to create a Product instance from a data reader. It won't help with this specific problem of not having all the fields present, but if you're doing a lot of old-fashioned ADO.NET like this it can be quite handy.
Although connection.GetSchema("Tables") does return meta data about the tables in your database, it won't return everything in your sproc if you define any custom columns.
For example, if you throw in some random ad-hoc column like *SELECT ProductName,'Testing' As ProductTestName FROM dbo.Products" you won't see 'ProductTestName' as a column because it's not in the Schema of the Products table. To solve this, and ask for every column available in the returned data, leverage a method on the SqlDataReader object "GetSchemaTable()"
If I add this to the existing code sample you listed in your original question, you will notice just after the reader is declared I add a data table to capture the meta data from the reader itself. Next I loop through this meta data and add each column to another table that I use in the left-right code to check if each column exists.
Updated Source Code
Using reader As SqlDataReader = cmd.ExecuteReader()
Dim table As DataTable = reader.GetSchemaTable()
Dim colNames As New DataTable()
For Each row As DataRow In table.Rows
colNames.Columns.Add(row.ItemArray(0))
Next
Dim product As Product While reader.Read()
product = New Product()
If Not colNames.Columns("ProductID") Is Nothing Then
product.ID = Convert.ToInt32(reader("ProductID"))
End If
product.SupplierID = Convert.ToInt32(reader("SupplierID"))
product.CategoryID = Convert.ToInt32(reader("CategoryID"))
product.ProductName = Convert.ToString(reader("ProductName"))
product.QuantityPerUnit = Convert.ToString(reader("QuantityPerUnit"))
product.UnitPrice = Convert.ToDouble(reader("UnitPrice"))
product.UnitsInStock = Convert.ToInt32(reader("UnitsInStock"))
product.UnitsOnOrder = Convert.ToInt32(reader("UnitsOnOrder"))
product.ReorderLevel = Convert.ToInt32(reader("ReorderLevel"))
productList.Add(product)
End While
This is a hack to be honest, as you should return every column to hydrate your object correctly. But I thought to include this reader method as it would actually grab all the columns, even if they are not defined in your table schema.
This approach to mapping your relational data into your domain model might cause some issues when you get into a lazy loading scenario.
Why not just have each sproc return complete column set, using null, -1, or acceptable values where you don't have the data. Avoids having to catch IndexOutOfRangeException or re-writing everything in LinqToSql.
Use the GetSchemaTable() method to retrieve the metadata of the DataReader. The DataTable that is returned can be used to check if a specific column is present or not.
Why don't you use LinqToSql - everything you need is done automatically. For the sake of being general you can use any other ORM tool for .NET
If you don't want to use an ORM you can also use reflection for things like this (though in this case because ProductID is not named the same on both sides, you couldn't do it in the simplistic fashion demonstrated here):
List Provider in C#
I would call reader.GetOrdinal for each field name before starting the while loop. Unfortunately GetOrdinal throws an IndexOutOfRangeException if the field doesn't exist, so it won't be very performant.
You could probably store the results in a Dictionary<string, int> and use its ContainsKey method to determine if the field was supplied.
I ended up writing my own, but this mapper is pretty good (and simple): https://code.google.com/p/dapper-dot-net/