Clean Code

• Emergence
• Meaningful Names
• Functions
• Classes

• Comments
• Formatting
• Error Handling
• Refactorin

Emergence

• Runs all the tests
• Contains no duplication
• Expresses the intent of the programmer
• Minimizes the number of classes and methods

Meaningful Names

• Intention-Revealing Names
• Avoid Disinformation
• Pronunciable Names
• Searchable Names
• Avoid Mental Mapping
• Don't be Cute

Bad!

Good!

Intention-Revealing Names

public List<int[]> getThem() {

 List<int[]> list1 = new ArrayList<int[]>();

 for (int[] x : theList)

 if (x[0] == 4) 

 list1.add(x);

 return list1;

 }

public List<Cell> getFlaggedCells() {

 List<Cell> flaggedCells = new ArrayList<Cell>();

 for (Cell cell : gameBoard)

 if (cell.isFlagged())

 flaggedCells.add(cell);

 return flaggedCells;

 }

Bad!

Good!

Avoid Disinformation

int a = l;

if ( O == l )

 a = 01;

else

 l = 01;

int number = value;

if ( ORIGINAL_VALUE == value )

 number = 01;

else

 value = 01;

Bad!

Good!

Pronunciable Names

class DtaRcrd102 {

private Date genymdhms; 

private Date modymdhms;

private final String pszqint = "102";

/* ... */

};

class Customer {

private Date generationTimestamp; 

private Date modificationTimestamp;;

private final String recordId = "102";

/* ... */

};

Bad!

Good!

Searchable Names

for (int j=0; j<34; j++) {
s += (t[j]*4)/5;
}

int realDaysPerIdealDay = 4;
const int WORK_DAYS_PER_WEEK = 5;
int sum = 0;

for (int j=0; j < NUMBER_OF_TASKS; j++) {
int realTaskDays = taskEstimate[j] * realDaysPerIdealDay;
int realTaskWeeks = (realdays / WORK_DAYS_PER_WEEK);
sum += realTaskWeeks;
}

Bad!

Good!

Avoid Mental Mapping

List<Vehicle> v = vehicleService.list();
m.addAttribute("vehicles", v);

if(me == null){
	me = "";
}
		
if(r == null){
	r = RequestStatus.SUCCESS;
}
		
m.addAttribute("r", r);
m.addAttribute("me", me);
return "vehicle/list";

List<Vehicle> vehicles = vehicleService.list();
m.addAttribute("vehicles", vehicles);

if(message == null){
	message = "";
}
		
if(requestStatus == null){
	requestStatus = RequestStatus.SUCCESS;
}
		
m.addAttribute("requestStatus", requestStatus);
m.addAttribute("message", message);
return "vehicle/list";

Bad!

Good!

Don't be Cute

   HolyHandGrenade
 
   whack()

   eatMyShorts()

   DeleteItems

   kill()

   abort()

Functions

• Do One Thing
• Small
• Flag Arguments

• Function Arguments
• Command Query Separation

Classes

• Organization
  • Encapsulation
• Should Be Small
  • Single Responsability
  • Cohesion
• Organizing for Change
  • Isolating for Change

Comments

• Good Comments
  • ​​​Legal Comments
  • Informative
  • Clarification
  • Warning of Consequences

• Bad Comments
  • Redundant Comments
  • Journal Comments
  • Noise Comments
  • Scary Noise

Formatting

• Communication
• Clean

Bad!

public class Assert {
static public void assertTrue(String message, boolean condition)
{
if (!condition)
fail(message);
}
static public void assertTrue(boolean condition) {assertTrue(null, condition);}

static public void assertFalse
(
String message,
boolean condition
) {assertTrue(message, !condition);
}

static public void assertFalse(boolean
condition) 

{

assertFalse(null, condition);

}

public class Assert {
static public void assertTrue(String message, boolean condition) {
if (!condition)
fail(message);
}

static public void assertTrue(boolean condition) {
assertTrue(null, condition);
}

static public void assertFalse(String message, boolean condition) {
assertTrue(message, !condition);
}

static public void assertFalse(boolean condition) {
assertFalse(null, condition);
}

Good!