Author: Luca Zanini

  • How to change the look and feel of a view using css

    A lotus view open in a browser is very ugly but you can greatly improve using stylesheets (css); here I explain how to use the css in a lotus view in order to improve the look and feel and to display rows in alternate colors.

  • How to display an icon in the preferences

    In the Android preferences you can put different types of controls: check box, edit box, list,…, but none of these displays an icon (see Settings). Usually a preference consists of two lines, the title and the summary, and after you have clicked you get a dialog box where you can select the chosen item, as…

  • Running a fortran program from java

    In this post I write an example about how to launch a fortran executable form a java program passing some arguments and getting back a result. The chosen example uses code written in fortran to get primes, it is from Sieve of Eratosthenes.

  • Getting the variables of the outer class from an inner class

    The inner classes, and then not static, can access even if with some limitation to the variables of the outer class.

  • Truncatable primes

    Project Euler Problem 37: The number 3797 has an interesting property. Being prime itself, it is possible to continuously remove digits from left to right, and remain prime at each stage: 3797, 797, 97, and 7. Similarly we can work from right to left: 3797, 379, 37, and 3. Find the sum of the only…

  • Double-base palindromes

    From the Project Euler Problem 36: The decimal number, 585 = 10010010012 (binary), is palindromic in both bases. Find the sum of all numbers, less than one million, which are palindromic in base 10 and base 2. (Please note that the palindromic number, in either base, may not include leading zeros.) checked

  • How to implement Up Navigation

    In this example you can see how to implement the Up Navigation, i.e. the option to go back to a previous activity using the button in the upper left of the action bar. The previous activity can be a fixed activity or an activity determined at runtime.

  • Circular primes

    From the Project Euler Problem 35: The number, 197, is called a circular prime because all rotations of the digits: 197, 971, and 719, are themselves prime. There are thirteen such primes below 100: 2, 3, 5, 7, 11, 13, 17, 31, 37, 71, 73, 79, and 97. How many circular primes are there below…

  • Digit factorials

    From the Project Euler Problem 34: 145 is a curious number, as 1! + 4! + 5! = 1 + 24 + 120 = 145. Find the sum of all numbers which are equal to the sum of the factorial of their digits. Note: as 1! = 1 and 2! = 2 are not sums…

  • Replacing a Fragment in a Tab Layout with an ActionBar

    In the post Tab Layout in Android with ActionBar and Fragment the fragments can’t be replaced later, in this post I write the changes in order to replace the first fragment of the first tab with a third fragment using a button at runtime.