Author: Luca Zanini

  • Varargs: passing a variable number of arguments to a method

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    Luca Zanini
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    From version 5 of Java you can call a method passing a variable number of arguments. A variable of this type is called varargs, you can only use in a method signature and its syntax is the primitive type or object type followed by 3 dots (ellipsis).

  • Large sum

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    Luca Zanini
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    From the Project Euler Problem 13: Work out the first ten digits of the sum of the following one-hundred 50-digit numbers.

  • Validation of an Edit Box control in the XPages

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    Luca Zanini
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    In the XPages the “Edit Box” controls have some settings that allow you to perform simple validations. These settings are under the label “Validation” of the control and depend on the value of “Display Type” under the label “Data”; in the figure you can see a screenshot of the validation of an Edit Box control…

  • Highly divisible triangular number

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    Luca Zanini
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    From the Project Euler Problem 12: The sequence of triangle numbers is generated by adding the natural numbers. So the 7th triangle number would be 1 + 2 + 3 + 4 + 5 + 6 + 7 = 28. The first ten terms would be: 1, 3, 6, 10, 15, 21, 28, 36, 45,…

  • How to save the state of a WebView inside a Fragment of an Action Bar

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    Luca Zanini
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    The idea for this post came to me after reading the comment of Esthon Wood: “do you have any idea on how to save the state of the WebView? I mean, the webview refreshes everytime I tap on the tab.” in the post Tab Layout in Android with ActionBar and Fragment.

  • How to replace a Fragment in an ActionBar in mode NAVIGATION_MODE_TABS

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    Luca Zanini
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    In the post Tab Layout in Android with ActionBar and Fragment I wrote an example about tabs in an action bar where each label open a fragment that you can not change at runtime. In this post I explain how to replace a fragment with an other using a button.

  • Largest product in a grid

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    Luca Zanini
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    From the Project Euler Problem 11: In the 20×20 grid below, four numbers along a diagonal line have been marked in red. 08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08 49 49 99 40 17 81 18 57 60 87 17 40 98…

  • Summation of primes

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    Luca Zanini
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    From the Project Euler Problem 10: The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find the sum of all the primes below two million. checked A processor Intel® Core™ i7-2720QM CPU @ 2.20GHz × 8 takes about 6 minutes to complete this calculation.

  • Project Euler – Problem 9

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    Luca Zanini
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    From the Project Euler Problem 9: A Pythagorean triplet is a set of three natural numbers, a b c, for which, a2 + b2 = c2 For example, 32 + 42 = 9 + 16 = 25 = 52. There exists exactly one Pythagorean triplet for which a + b + c = 1000. Find…

  • Project Euler – Problem 8

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    Luca Zanini
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    From the Project Euler Problem 8:Find the greatest product of five consecutive digits in the 1000-digit number. 7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450 checked I wrote the digits in a file, I read the file and I set an ArrayList<Character>…