Java Gotchas

Students often ask for help and show me various things they have done in programs which has caused them some grief. Some of these are nasty gotchas, and some are really poor examples of things you don't want to do. Enjoy!

• Gotcha 1
• equality check gotcha

  boolean loop_again;
  
  while (loop_again = true)
  {
  

  Note what operator is bein used inside of the parenthesis?
• array gotcha

  grades[numElem++] = Double.parseDouble(strGrade);
  

  The problem here is if the parseDouble fails, numElem increments anyway, which gives an incorrect count.

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