Long Method
Penjelasan Smell
Smell ini terjadi ketika ada sebuah method yang terlalu panjang. Method yang terlalu panjang dapat ditentukan dengan beberapa indikator:
- Programmer kesulitan memahami method. Perlu membaca dengan detail baris per baris berulang-ulang untuk memahami tujuan code ini
- Programmer perlu menuliskan internal comment untuk mengklarifikasi tujuan beberapa line of code
- Satu method memiliki banyak tanggungjawab
- Terdapat hidden-side-effect di dalam method. Nama method tidak sesuai dengan apa yang dilakukan di dalamnya.
- Melebihi N baris. N ini merupakan angka yang ditentukan oleh masing-masing tim. Beda perusahaan atau beda bahasa pemrograman bisa beda angka. Di sourcemaking, dibilang tidak boleh lebih dari 10 baris.
Pada contoh SemesterMenu.java, terdapat method menu, create, dan delete yang melebihi 10 baris.
java
public class SemesterMenu {
private Vector<Semester> semesters;
private Scanner scan;
public SemesterMenu() {
semesters = new Vector<Semester>();
scan = new Scanner(System.in);
}
public void open() {
while(menu()) {}
}
private boolean menu(){
//menampilkan semua semester yang ada
for(int i = 0; i < semesters.size(); i++) {
Semester s = semesters.elementAt(i);
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
System.out.print((i+1) + ". ");
System.out.print(s.getLabel());
System.out.print(" - ");
System.out.print(format.format(s.getStart()));
System.out.print(" - ");
System.out.print(format.format(s.getEnd()));
System.out.println("");
}
System.out.println("");
//menampilkan menu
System.out.println("1. Create");
System.out.println("2. Delete");
System.out.println("3. Exit");
//input
int input = 0;
do{
System.out.print("Input [1-3]: ");
try {
input = scan.nextInt();
} catch (Exception e) {
input = 0;
} finally {
scan.nextLine();
}
}while(input < 1 || input > 3);
//switch menu by input
switch(input){
case 1: create(); break;
case 2: delete(); break;
case 3: return false;
}
return true;
}
private void delete() {
int input = 0;
do{
System.out.print("Choose semester [1-"+semesters.size()+"]: ");
try {
input = scan.nextInt();
} catch (Exception e) {
input = 0;
} finally {
scan.nextLine();
}
}while(input < 1 || input > semesters.size());
semesters.removeElementAt(input-1);
}
private void create() {
String label = "";
do {
System.out.print("Input label [3-20 chars]: ");
label = scan.nextLine().trim();
} while(label.length() < 3 || label.length() > 20 || !isLabelUnique(label));
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
format.setLenient(false);
Date startDate = null;
Date endDate = null;
do {
do {
try {
System.out.print("Input start date [yyyy-MM-dd]: ");
String input = scan.nextLine().trim();
startDate = format.parse(input);
} catch (Exception e) {
startDate = null;
}
} while(startDate == null);
do {
try {
System.out.print("Input end date [yyyy-MM-dd]: ");
String input = scan.nextLine().trim();
endDate = format.parse(input);
} catch (Exception e) {
endDate = null;
}
} while(endDate == null);
}while(startDate.after(endDate));
semesters.add(new Semester(label, startDate, endDate));
}
private boolean isLabelUnique(String label) {
for(Semester s : semesters) {
if(s.getLabel().equalsIgnoreCase(label)) return false;
}
return true;
}
}public class SemesterMenu {
private Vector<Semester> semesters;
private Scanner scan;
public SemesterMenu() {
semesters = new Vector<Semester>();
scan = new Scanner(System.in);
}
public void open() {
while(menu()) {}
}
private boolean menu(){
//menampilkan semua semester yang ada
for(int i = 0; i < semesters.size(); i++) {
Semester s = semesters.elementAt(i);
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
System.out.print((i+1) + ". ");
System.out.print(s.getLabel());
System.out.print(" - ");
System.out.print(format.format(s.getStart()));
System.out.print(" - ");
System.out.print(format.format(s.getEnd()));
System.out.println("");
}
System.out.println("");
//menampilkan menu
System.out.println("1. Create");
System.out.println("2. Delete");
System.out.println("3. Exit");
//input
int input = 0;
do{
System.out.print("Input [1-3]: ");
try {
input = scan.nextInt();
} catch (Exception e) {
input = 0;
} finally {
scan.nextLine();
}
}while(input < 1 || input > 3);
//switch menu by input
switch(input){
case 1: create(); break;
case 2: delete(); break;
case 3: return false;
}
return true;
}
private void delete() {
int input = 0;
do{
System.out.print("Choose semester [1-"+semesters.size()+"]: ");
try {
input = scan.nextInt();
} catch (Exception e) {
input = 0;
} finally {
scan.nextLine();
}
}while(input < 1 || input > semesters.size());
semesters.removeElementAt(input-1);
}
private void create() {
String label = "";
do {
System.out.print("Input label [3-20 chars]: ");
label = scan.nextLine().trim();
} while(label.length() < 3 || label.length() > 20 || !isLabelUnique(label));
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
format.setLenient(false);
Date startDate = null;
Date endDate = null;
do {
do {
try {
System.out.print("Input start date [yyyy-MM-dd]: ");
String input = scan.nextLine().trim();
startDate = format.parse(input);
} catch (Exception e) {
startDate = null;
}
} while(startDate == null);
do {
try {
System.out.print("Input end date [yyyy-MM-dd]: ");
String input = scan.nextLine().trim();
endDate = format.parse(input);
} catch (Exception e) {
endDate = null;
}
} while(endDate == null);
}while(startDate.after(endDate));
semesters.add(new Semester(label, startDate, endDate));
}
private boolean isLabelUnique(String label) {
for(Semester s : semesters) {
if(s.getLabel().equalsIgnoreCase(label)) return false;
}
return true;
}
}java
public class Main {
public static void main(String[] args) {
new Main();
}
public Main() {
SemesterMenu semesterMenu = new SemesterMenu();
semesterMenu.open();
}
}public class Main {
public static void main(String[] args) {
new Main();
}
public Main() {
SemesterMenu semesterMenu = new SemesterMenu();
semesterMenu.open();
}
}java
public class Semester {
private String label;
private Date start;
private Date end;
public Semester(String label, Date start, Date end) {
super();
this.label = label;
this.start = start;
this.end = end;
}
public String getLabel() {
return label;
}
public Date getStart() {
return start;
}
public Date getEnd() {
return end;
}
}public class Semester {
private String label;
private Date start;
private Date end;
public Semester(String label, Date start, Date end) {
super();
this.label = label;
this.start = start;
this.end = end;
}
public String getLabel() {
return label;
}
public Date getStart() {
return start;
}
public Date getEnd() {
return end;
}
}Penyelesaian
Dilakukan Extract Method pada method menu, create, dan delete.
java
public class SemesterMenu {
private Vector<Semester> semesters;
private Scanner scan;
public SemesterMenu() {
semesters = new Vector<Semester>();
scan = new Scanner(System.in);
}
public void open() {
while(menu()) {}
}
private boolean menu(){
showSemesters();
int input = printAndGetMenu();
switch(input){
case 1: create(); break;
case 2: delete(); break;
case 3: return false;
}
return true;
}
private void create() {
String label;
do {
label = getStringInput("Input label", 3, 20);
} while(!isLabelUnique(label));
Date startDate, endDate;
do {
startDate = getDateInput("Input start date", "yyyy-MM-dd");
endDate = getDateInput("Input end date", "yyyy-MM-dd");
} while(startDate.after(endDate));
semesters.add(new Semester(label, startDate, endDate));
}
private boolean isLabelUnique(String label) {
for(Semester s : semesters) {
if(s.getLabel().equalsIgnoreCase(label)) return false;
}
return true;
}
private void delete() {
int input = getIntInput("Choose semester", 1, semesters.size());
semesters.removeElementAt(input-1);
}
private int printAndGetMenu() {
System.out.println("1. Create");
System.out.println("2. Delete");
System.out.println("3. Exit");
return getIntInput("input menu", 1, 3);
}
private void showSemesters() {
for(int i = 0; i < semesters.size(); i++) {
Semester s = semesters.elementAt(i);
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
System.out.print((i+1) + ". ");
showSemester(s, format);
System.out.println("");
}
System.out.println("");
}
private void showSemester(Semester s, SimpleDateFormat format) {
System.out.print(s.getLabel());
System.out.print(" - ");
System.out.print(format.format(s.getStart()));
System.out.print(" - ");
System.out.print(format.format(s.getEnd()));
}
private Date getDateInput(String message, String format) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
sdf.setLenient(false);
Date date = null;
do {
try {
System.out.print(message + " ["+format+"]: ");
String input = scan.nextLine().trim();
date = sdf.parse(input);
} catch (Exception e) {
date = null;
}
} while(date == null);
return date;
}
private int getIntInput(String message, int min, int max) {
int input;
do{
System.out.print(message + " ["+min+"-"+max+"]: ");
try {
input = scan.nextInt();
} catch (Exception e) {
input = 0;
} finally {
scan.nextLine();
}
}while(input < min || input > max);
return input;
}
private String getStringInput(String message, int min, int max) {
String input;
do{
System.out.print(message + " ["+min+"-"+max+" chars]: ");
input = scan.nextLine().trim();
}while(input.length() < min || input.length() > max);
return input;
}
}public class SemesterMenu {
private Vector<Semester> semesters;
private Scanner scan;
public SemesterMenu() {
semesters = new Vector<Semester>();
scan = new Scanner(System.in);
}
public void open() {
while(menu()) {}
}
private boolean menu(){
showSemesters();
int input = printAndGetMenu();
switch(input){
case 1: create(); break;
case 2: delete(); break;
case 3: return false;
}
return true;
}
private void create() {
String label;
do {
label = getStringInput("Input label", 3, 20);
} while(!isLabelUnique(label));
Date startDate, endDate;
do {
startDate = getDateInput("Input start date", "yyyy-MM-dd");
endDate = getDateInput("Input end date", "yyyy-MM-dd");
} while(startDate.after(endDate));
semesters.add(new Semester(label, startDate, endDate));
}
private boolean isLabelUnique(String label) {
for(Semester s : semesters) {
if(s.getLabel().equalsIgnoreCase(label)) return false;
}
return true;
}
private void delete() {
int input = getIntInput("Choose semester", 1, semesters.size());
semesters.removeElementAt(input-1);
}
private int printAndGetMenu() {
System.out.println("1. Create");
System.out.println("2. Delete");
System.out.println("3. Exit");
return getIntInput("input menu", 1, 3);
}
private void showSemesters() {
for(int i = 0; i < semesters.size(); i++) {
Semester s = semesters.elementAt(i);
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
System.out.print((i+1) + ". ");
showSemester(s, format);
System.out.println("");
}
System.out.println("");
}
private void showSemester(Semester s, SimpleDateFormat format) {
System.out.print(s.getLabel());
System.out.print(" - ");
System.out.print(format.format(s.getStart()));
System.out.print(" - ");
System.out.print(format.format(s.getEnd()));
}
private Date getDateInput(String message, String format) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
sdf.setLenient(false);
Date date = null;
do {
try {
System.out.print(message + " ["+format+"]: ");
String input = scan.nextLine().trim();
date = sdf.parse(input);
} catch (Exception e) {
date = null;
}
} while(date == null);
return date;
}
private int getIntInput(String message, int min, int max) {
int input;
do{
System.out.print(message + " ["+min+"-"+max+"]: ");
try {
input = scan.nextInt();
} catch (Exception e) {
input = 0;
} finally {
scan.nextLine();
}
}while(input < min || input > max);
return input;
}
private String getStringInput(String message, int min, int max) {
String input;
do{
System.out.print(message + " ["+min+"-"+max+" chars]: ");
input = scan.nextLine().trim();
}while(input.length() < min || input.length() > max);
return input;
}
}java
public class Main {
public static void main(String[] args) {
new Main();
}
public Main() {
SemesterMenu semesterMenu = new SemesterMenu();
semesterMenu.open();
}
}public class Main {
public static void main(String[] args) {
new Main();
}
public Main() {
SemesterMenu semesterMenu = new SemesterMenu();
semesterMenu.open();
}
}java
public class Semester {
private String label;
private Date start;
private Date end;
public Semester(String label, Date start, Date end) {
super();
this.label = label;
this.start = start;
this.end = end;
}
public String getLabel() {
return label;
}
public Date getStart() {
return start;
}
public Date getEnd() {
return end;
}
}public class Semester {
private String label;
private Date start;
private Date end;
public Semester(String label, Date start, Date end) {
super();
this.label = label;
this.start = start;
this.end = end;
}
public String getLabel() {
return label;
}
public Date getStart() {
return start;
}
public Date getEnd() {
return end;
}
}Code di dalam method menu diekstrak menjadi showSemesters(), printAndGetMenu(), dan showSemester().
Untuk method create, delete, dan bagian code input menu. Kita dapat melihat terdapat duplicate code yang juga membuat method menjadi panjang. Hal ini dapat diatasi dengan mengakali logic input menjadi method getDateInput, getIntInput, dan getStringInput.
Tambahan
Refactor pada contoh SemesterMenu ini belum selesai. Terdapat smell Large Class yang akan diurus disini.