I’m learning a ton this summer as I relearn old tricks and learn new tricks. Among other technologies, frameworks, languages, and techniques, I’m improving my Java skills. A friend recommended Joshua Block’s Effective Java Version 2 (affiliate link). The introduction succinctly states that the book aims to improve your usage of Java–something not usually taught in classes or discussed in book. Here are a few things I (re)learned:

  • Local variables should be instantiated; if you cannot assign a sane default value, you shouldn’t be assigning the variable yet.
  • Variables should be located near their use. In the C style you would declare all variables at the top of the method; however, this is not the best practice in modern Java. (Does anyone know if the ‘variables at top’ still reigns in C?)
  • while loops should be used only if you need the local index variable outside the loop
  • For-each loops should be used whenever possible

  • The next best loop is a for loop with the end condition assigned in the loop (a technique I believe we could weakly call memoization because we only have to calculate something once), for example:

    for (int i = 0, len = myDataStructure.calculateSomething(); i < len; i++) { // do something }