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Closed 10 years ago.
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Plot Graphs in Java
I was trying to create graphs for x and y values in my java Application. Unfortunately while using the libraries in http://www.epic.noaa.gov/java/sgt/index.html, i found that most of the classes/ methods are deprecated. Kindly help me find a way out of this. Is there any alternate library that i can use to construct a graph. I have a for loop in which i generate the x and y values. Therefore, a method where i can directly feed data and then at the end of the loop create a graph would be nice.
Try this one here, this is the link, yes this is it: http://www.jfree.org/
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Is there a concurrent List in Java's JDK?
(8 answers)
Closed 5 years ago.
I have a list of accounts that will be updated - not too frequent ~1-2 times a day.
There would be a 'contains' lookup on this data at much regular interval.
An ideal data structure would have been ConcurrentLinkedList ,which unfortunately isnt around.
Is CopyOnWriteArrayList the sole preferred option?
If you are reading mostly , why you need concurrent data structure. Instead you can use HashSet or HashMap. It will make read faster. It is updated so less frequently then u can synchronise the writing part explicitly.
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How to step back in Eclipse debugger?
(6 answers)
Closed 6 years ago.
I have the following doubt about the Eclipse debugger dbugging a Java application.
When it stop on a break point I know that I can go to the next step. But can I also go to the previous one?
The best compromise is "Drop to Frame" (one of the icons in the debugging area), which essentially resets the stack frame and puts you at the top of the method. This won't reset any external side effects, so if some code between the top of the method and your current position changed any properties of an object, you'll have to deal with that.
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Turn Image into Text - Java [duplicate]
(4 answers)
Closed 7 years ago.
I want to search a word from image(scanned copy), retrieve values from image, highlight the location. Is there any API or library available for processing images. I am using Swing for displaying images.
You need something to convert the pixels into characters. That something is a program that provides OCR.
Keep in mind that any program you use will provide its best approximation of what it thinks the character is. While technology has improved a lot, there are many fonts, sufficient noise, and various other confounding factors that could result in false input (where the character is not what you would have deemed it to be). There are also scenarios where the input cannot be mapped to a character. Write your software defensively to handle both cases, as this should be considered "non validated input".
Check out "tesseract". It isn't Java, put available for most platforms open-source, and you can call the command-line program from java via System.exec()
https://code.google.com/p/tesseract-ocr/
given the images in the correct format, it's recognition rate is even better than many commercial OCR software products.
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implement AbstractTableModel for a Java collection
(6 answers)
Closed 8 years ago.
I have created a JTable using AbstractTableModel in which I added a collection of objects (ArrayList).
I want to be able to search through the objects and return in the same JTable only the ones that meet a conditions (for example the names starts with "St"). Theoretically, how can I do that? Do I have to make new ArrayLists for every condition, and store these searched (and returned) objects there? Is there a better/simpler way? Thanks
As shown here, you can access a Collection in your implementation of AbstractTableModel. As shown here, you can sort and filter the results without modifying the original data structure. A complete example is examined here.
here is the thing,
if you are looking for syntaxic filtering this functionality already exists in java as TableRowSorter which can be combined with row filter to set the subList and show it.
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I spent quite some time researching for a library that allows me to compare images to one another in Java.
I didn't really find anything useful, maybe my GoogleSearch-skill isn't high enough so I thought I'd ask you guys if you could point me into a direction of where I could find something like this.
Basically what I want to do is to compare two images with each other and get a value of how much the two are similar. Like a percentage or so.
I hope you guys have something I can use, I wouldn't know how to write something like that myself...
PS: It doesn't necessarily has to be in Java, that's just the environment my app will be running.
You could take a look at two answers on SO itself: this one is about image comparison itself, offering links to stuff in C++ (if I read correctly) while this one offers links to broader approaches, one being in C.
I would suggest starting with the second link since there's links on that discussion that'll lead to implementation code of some relevant techniques which you might be able to "translate" into Java yourself.
That's the best my google skills could do, no Java though - sorry. I hope it's a good starting point!
EDIT:
Here's someone with your problem who wrote his own comparison class in Java. I didn't read the source code though. He expressly states that he couldn't find Java libraries for that purpose either, so that's why he wrote it himself.
Oh, and this question on SO has probably the best links on this, all regarding Java libraries of image processing. Hopefully there's one amongst them that can compare images for similarity.
Ok, last edit:
The Java Image Processing Cookbook shows a Java implementation of a basic algorithm to determine the difference between two pictures. It also has an email to contact the guy who wrote it as well as a host of references. No library though.
EDIT after reading your comment to your question:
Unless you've already checked all of the above links, since what you want seems to be checking whether two images are equal, I would suggest starting with the Java Image Processing Cookbook (since that has an implementation of an algorithm in Java to check for equal images) and the last link to an SO question. Also, check PerceptualImageDiff and the source code of that project (C++); it sounds really nifty - it's apparently supposed to check whether two images look equal to the human visual system.
Just off the top of my head, OpenCV is a great image processing library, but it might be overkill if you just want to compare images. If that's the case, I'd go with ImageJ.
Someone already asked how to do this using OpenCV here.
I'd use C++ for this, but if you must use Java, there is a project which made a Java wrapper for OpenCV, here.
I used the class in this link to compare two product images, and the results were cool. It's not very hard to implement it just to be used for comparing two images, you just need to delete the lines of JAI and Swing and such. It resizes images to 300x300 and returns a difference value such as "1234". The maximum difference value is near "11041", it's stated in the link. Doing a division, you can simply get the percentage. If interested I can post the modified code here later.
The results were cool, but I still got "digital camera photos", detected to be similar to "TV photos". So, I used ImageJ to detect edges in the picture. Using the detect edges operation, ImageJ converts the image into a edge detected greyform image. Than I put the two edge-detected images in the same comparator and multiplied the both values. The results got even more accurate.
Getting the edge-detected form of the images