Concurrent Hashmap clears itself. [closed] - java

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I have a xml reader which reads the title and the name of a person in java from a rss feed. I accomplish this by using document builder in java. When I read the element title and element name, I put them into a concurrent hashmap. This is fine, I can get the values from the map. However I want this information to be stored there for some time limit and not call the document builder until this time limit has passed. But the problem is when I do not call the document builder and refresh the webpage my hashmap values seem not to be stored. Code is in java and wicket.
Thoughts ?

It may be that every time you're refreshing the page a new hashmap is built and the old one is simply discarded. You should make sure your data stays persistent.

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Has operation in Android SQLite [closed]

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I have a some trouble about my own simple android project. I save data pair (key-value), and I dont want to save same data. ( for example: I save the data "Car"- "Blue" once. and then application can not permisson save again same the data.) I wrote already update method but I couldnt use for search & control data repetition. How can I solve ?
Make the combination of the two columns a Primary Key
You can also use if else block along with SELECT statement to validate inputs.

XML Document Parsing in Java [closed]

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I need to parse an XML document in java for a web service I'm making, and save the contents of it.
I need to save the name of the tags, if the tag has attributes save the attributes, and then save the data within those tags. These three items will be inserted into a database table with the three columns tags, attributes, and data.
I'm using the following java libraries:
javax.xml.parsers.DocumentBuilder
javax.xml.parsers.DocumentBuilderFactory
org.w3c.dom.Document, org.w3c.dom.NodeList
org.xml.sax.InputSource.
Any help would be much appreciated.
DISCLAIMER: I don't want to plagiarize so I didn't include code but included links to other tutorials that are VERY helpful to this topic.
First, you should read w3c dom's java API because it tells you a lot of useful functions that are very related to your question.
Second, this website contains a useful tutorial that's easy to understand and it contains the necessary information for you to get the attributes of tags.
Third, this website gives you info on how to get tagName when you are looping through elements.
Fourth, you should always read related API, google, and then post a question if you are have no clue after a LONG period of time.
Lastly, you should post a difference question or research on database FIRST before asking that question here. This question should only be about XML Document Parsing in Java.
We are not supposed to help you do anything so the API is the best help for you (and google).
API: https://docs.oracle.com/javase/7/docs/api/org/w3c/dom/package-summary.html

Setting TextField limit [closed]

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I created a swing application which has a string named textField, and I need to append in a string named textArea. My Problem is; when it appends, it doesn't align, since the names are different .
I want to make it accept 25 characters only, and if less than 25 were entered they are filled with spaces.
Is there any way this can be done? I Have been on it since morning without making any headway.
Any suggestion would be greatly appreciated, thanks in advance.
Every Text Component in java associates with a model to maintain it's text content known as Document. A Document has: DocumentListener to listen to changes made to it which generates event on it's content update. you can also use DocumentFilter with Document to change how the text component's data is set. You can implement certain customizations either by installing a document filter or by replacing a text component's document with one of your own.
Check out the example and tutorial:
How to write DocumentListener
Implementing a Document Filter
DocumentSizeFilter

Consistency in cassandra [closed]

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Does in AP of the CAP theorm, is there a possibility (like in cassandra), that if i write/update to cassandra and immediately try to fetch it, can there a chance the data is not found or should my read o/p be paused before being fetched (hence allowing replications to settle in).
Can someone direct me to any link where people have addressed the consistency issue in cassandra.
Cassandra can be used to give the consistency that you describe. If the number of nodes you read from (R) plus the number of nodes you write to (W) is greater than the replication factor (N), you will read back a value immediately after it was written (assuming there are no concurrent writers who may write a later value in the small window since you wrote). So as long as R+W>N you will get this behaviour.
A common way to do this is to read and write at CL.QUORUM, since this gives you good availability. You could also e.g. read at CL.ONE and write at CL.ALL, but then writes will fail if a single node is down.

How store data on a special id and get this data from this id? [closed]

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I would say I'm a newbie in programming and I need to store some data on an Id.
And then get the right data to an Id.
How can I do this?
Have you heard about Map and its Implementation. It stores the value in (Key,Value) pair.
Read this.
You can use your id as a key and its value in Map. and retrieve it using id easily.
if you need to store data in ID in android u flallow [http://developer.android.com/guide/topics/manifest/meta-data-element.html]
then you get the result
(or)
Cheak this link : (Canvas, animated text rotation)
Use HashMap. it key value date structure and stores data on the basis of id

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