I want to know if I can create an array of XYChart.Series<String, Number> on JavaFX?
Because I need to create a XYChart.Series for each person on database, and I tried to make an array of XYChart.Series<String, Number> for my LineChart but I couldn't.
This is what I tried:
List<XYChart.Series<String, Number>> seriesList = new ArrayList<XYChart.Series<String, Number>>();
Because I had no idea how to do it otherways.
Can you please help me?
You can create a array of the raw type and assign it to a variable declared with a generic type.
int size = ...
XYChart.Series<String, Number>[] seriesArray = new XYChart.Series[size];
Update
Array elements still need to be initialized this way since arrays generated this way are filled with null elements.
Java 8 provides a way create & initilize a array using short code via streams API:
XYChart.Series<String, Number>[] seriesArray = Stream.<XYChart.Series<String, Number>>generate(XYChart.Series::new).limit(size).toArray(XYChart.Series[]::new);
Related
Can anyone teach me how to initiate/add items in array as section?
something like - array[["john"],["daniel"],["jane"]]
tried a few like var d = ArrayList<CustomClass>(arrayListOf<CustomClass>())
that does not work.
for example, if i add "david" i want it look like array[["john"],["daniel", "david"],[“keith"]] by finding the index of array contains letter "d"
how can i display them on a custom base adapter / listview? currently using a viewHolder
val viewHolder = ViewHolder(row.name) to display.
Thanks!
If I am right, you're trying to create an ArrayList that contains other ArrayLists. So writing:
var d = ArrayList<CustomClass>(arrayListOf<CustomClass>())
Won't work because the type of the main ArrayList is not String, but ArrayList. So you need to write:
var names = ArrayList<ArrayList<String>>()
names.add(arrayListOf("jane", "john))
Regarding the second question, check out this course that has a section about RecyclerView: https://classroom.udacity.com/courses/ud9012 If you are a beginner, I strongly encourage you to follow the whole tutorial.
I have this array where I set the keys on the creation. Now in some point in my view I load some more information based on ids (the keys).
var colors = [
"37027" : UIColor(red:150/255, green:57/255, blue:103/255, alpha:1),
"12183" : UIColor(red:234/255, green:234/255, blue:55/255, alpha:1),
"44146" : UIColor(red:244/255, green:204/255, blue:204/255, alpha:1)
]
I want to add more colors to this array dynamically. How can I insert new items in the array setting the key? Something like
colors["25252"] = UIColor(red:244/255, green:204/255, blue:204/255, alpha:1)
The line above doesn't work, it is just to illustrate what I need.
Thanks for any help
Update: the code above is an example. Below the real code:
var placedBeacons : [BeaconStruct] = []
BeaconModel.fetchBeaconsFromSqlite(completionHandler: {
beacons in
for item in beacons{
self.placedBeacons["\(item.major):\(item.minor)"] = item
}
})
Error: Cannot subscript a value of type '[BeaconStruct]' with an index of type String
To match the key subscripting
self.placedBeacons["\(item.major):\(item.minor)"] = item
you have to declare placedBeacons as dictionary rather than an array
var placedBeacons = [String:BeaconStruct]()
It requires that item is of type BeaconStruct
The code you wrote, it should work. I have used such kind of code and was able to implement successfully. I just tested your code in my end and it's working for me. I declared colors variable globally in my class file and in view did load method added the second code to add another item in my colors array. After printing it out. My output shows full list of array with 4 items and the number of array count return 4 as well.
Please let me know, more details of your scenario so i can help you to figure it out the issue. but looks like it should work.
I want to create an array of JEditorPane depending on the size of a String array.
Is there a possibility to create an array of JEditorPane? If yes, how?
Here is an example:
String [] elements = {"0","1","2","3","4"};
JEditorPane ePane [] = new JEditorPane[5];
I want to to put each String element into the certain JEditPane, i.e
JEditorPane[0].setText(elements[0]);
etc. But I get a nullpointerexception when run I run.
Your problem is, that Java initializes a new array with the default value for the given type. In this case it is null, because the JEditorPane inherits from Object.
You cannot call a method on null - that is where the NullPointerException comes from.
The solution: make a loop in which you initialize the JEditorPane-objects in the array.
Then you can do JEditorPane[0].setText(elements[0]);
I want to save my Array's strucure and load it the next time I open my AIR application. Is there a way to store it to an EncryptedLocalStore item then get it later when I re-open the app?
EncryptedLocalStore.setItem() method takes a byte array when storing contents. To store an array, just use ByteArray.writeObject() method (as described in http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/utils/ByteArray.html#writeObject()) to convert your Array to a ByteArray - and then persist the same to the ELS.
var array:Array = getArray();
var byteArray:ByteArray = new ByteArray();
byteArray.writeObject(array);
EncryptedLocalStore.setItem('somekey', byteArray);
Hope this helps.
Update: Added code to retrieve the array back.
var byteArray:ByteArray = EncryptedLocalStore.getItem('somekey');
var array:Array = byteArray.readObject() as Array;
Update: For custom classes.
In case you want to serialize your own custom classes to the ByteArray, you may have to call registerClassAlias() before writing the object to the ByteArray. For eg.
registerClassAlias("com.example.eg", ExampleClass);
I have found that it is easiest to to serialize the Array to a string and then store that string in the ELS. Then when you pull it out deserialize it back into an Array.
I'm learning Delphi Prism, and i don't find how to write the following code with it :
type
TRapportItem = record
Label : String;
Value : Int16;
AnomalieComment : String;
end;
type
TRapportCategorie = record
Label : String;
CategoriesItems : Array of TRapportItem;
end;
type
TRapportContent = record
Categories : array of TRapportCategorie;
end;
Then, somewhere, i try to put items in the array :
rapport.Categories[i].Label:=l.Item(i).InnerText;
But it doesn't work.. Can someone enlight me?
Thanks!
You didn't specify exactly what "didn't work". You should include the error in questions like this.
Arrays are reference types, and they start out with the value nil. They need to be initialized before elements can be accessed.
You can do this with the new operator:
rapport.Categories = new TRapportCategorie[10]; // 0..9
Arrays are quite a low-level type. Usually it's better to work with List<T> instead.
So you'd declare:
Categories: List<TRapportCategorie>;
But lists also need initializing, using the new operator. Also, modifying the return value of the indexer on a list containing a value type will be modifying a copy, not the original, which leads to the next point.
Records are usually not the best data type for representing data, as they are not reference types; it's very easy to end up modifying a copy of the data, rather than the original data. It's usually best to use classes instead, where you can put all the initialization code (such as allocating the array or list) in the constructor.