Table of Contents

• 1. KISS
• 2. DRY
• 3. Readability
  • 3.1 Parameters
  • 3.2 Conditions
• 4. Lines of code

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1. KISS

• KISS means Keep it small and simple
• Make it as simple as possible, but not simpler (Albert Einstein)

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2. DRY

• DRY means Don't repeat yourself
• The opposite is WET:
  • Write everyting twice
  • We enjoy typing
  • Waste everyone's time

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3. Readability

3.1 Parameters

• What's the problem with the following code?

  Rook rook = new Rook(true);

• Problem: The code is hard to read. What is the meaning of the boolean parameter value true?
• Solution: Use enumerations instead of booleans as parameters:

enum COLOR { BLACK, WHITE }
Rook rook = new Rook(COLOR.WHITE}

3.2 Conditions

Question: What is the output of the following java code?

   int i = 0; int j = 1;
   if (i == 1)
      if (j==1)
         System.out.println("j == 1");
   else
      System.out.println("i != 1");

Answer: Nothing. Reason: The else belongs to the inner if. Solution: Always write parentheses in if statements. Format your code correctly

   int i = 0; int j = 1;
   if (i == 1) {
      if (j==1) {
         System.out.println("j == 1");
      }
      else
      {
         System.out.println("i != 1");
      }
   }

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4. Lines of code

• Hypotheses: Mimimize your lines of code. Except you get payed for it. Less code are less errors.
• Question: How would you write code to validate an E-Mail address?
• Answer: Use a regular expression.
• Example: '\b[A-Z0-9._%+-]+@[A-Z0-9.-]+.[A-Z]{2,}\b'