Java重构示例

1.尽量简洁

1.1重构前

if ( flag == 1 ){
    return true;
}
else{
    return false;
}

1.2重构后

return flag == 1;

2.使用三位运算符

2.1重构前

if ( "Male".equals(gender) ) {
    return "Mr.";
}
else{
    return "Mrs.";
}

2.2重构后

return "Male".equals(gender) ? "Mr." : "Mrs.";

3.使用常量替换硬编码

3.1重构前

for (int i = 0; i < 12; i++) {
    this.getDays(i);
    //skip...
}

3.2重构后

int YEAR_MONTHS = 12;
for (int month = 0; month < Month.YEAR_MONTHS; month++) {
    this.getDays(month);
    //skip...
}

4.使用方法替换反复出现的表达式

4.1重构前

public boolean isStartAfter(Date date) {
    Calendar calendar = BusinessCalendar.getCalendar();
    calendar.setTime(date);
    int hour = calendar.get(Calendar.HOUR_OF_DAY);
    int minute = calendar.get(Calendar.MINUTE);
    
    return ((hour<fromHour) || ((hour==fromHour) && (minute<=fromMinute)));
  }


  public boolean includes(Date date) {
    Calendar calendar = BusinessCalendar.getCalendar();
    calendar.setTime(date);
    int hour = calendar.get(Calendar.HOUR_OF_DAY);
    int minute = calendar.get(Calendar.MINUTE);
    
    return (((fromHour<hour) || ((fromHour==hour) && (fromMinute<=minute))) && ( (hour<toHour) || ( (hour==toHour) && (minute<=toMinute))));
  }

4.2重构后

private boolean tailGreatHead(int headHour, int headMinute, int tailHour, int tailMinute, boolean includeEqual) {
    boolean tailGreatHeadHour = (headHour < tailHour);
    boolean tailEqualHeadHour = (headHour == tailHour);
    boolean tailGreatHeadMinute = (headMinute < tailMinute);
    boolean tailEqualHeadMinute = (headMinute == tailMinute);

    boolean tailGreatEqualHeadMinute = tailGreatHeadMinute || includeEqual && tailEqualHeadMinute;

    return (tailGreatHeadHour || (tailEqualHeadHour && tailGreatEqualHeadMinute));
  }

  private boolean tailGreatHead(int headHour, int headMinute, int tailHour, int tailMinute) {
    return tailGreatHead(headHour, headMinute, tailHour, tailMinute, false);
  }

  private boolean tailGreatEqualHead(int headHour, int headMinute, int tailHour, int tailMinute) {
    return tailGreatHead(headHour, headMinute, tailHour, tailMinute, true);
  }

  public boolean isStartAfter(Date date) {
    Calendar calendar = BusinessCalendar.getCalendar();
    calendar.setTime(date);
    int hour = calendar.get(Calendar.HOUR_OF_DAY);
    int minute = calendar.get(Calendar.MINUTE);
    
    return this.tailGreatEqualHead(hour, minute, fromHour, fromMinute);
  }


  public boolean includes(Date date) {
    Calendar calendar = BusinessCalendar.getCalendar();
    calendar.setTime(date);
    int hour = calendar.get(Calendar.HOUR_OF_DAY);
    int minute = calendar.get(Calendar.MINUTE);
    
    return this.tailGreatEqualHead(fromHour, fromMinute, hour, minute) && this.tailGreatEqualHead(hour, minute, toHour, toMinute);
  }

5.及早结束非正常逻辑

5.1重构前

int count = 0;
if(taskList != null && !taskList.isEmpty()){

  //skip...

  return count;
} else {
  return count;
}

5.2重构后

int count = 0;
if(taskList == null || taskList.isEmpty()){
  return 0;
}

//skip...

return count;

6.满足条件立即跳出循环

6.1重构前

public boolean contain(int year, Month month, int day) {
  boolean found = false;
  for (IPolyDate date : dateList) {
    if (date.same(year, month.getMonth(), day)) {
      found = true;
      break;
    }
  }

  return found;
}

6.2重构后

public boolean contain(int year, Month month, int day) {
  for (IPolyDate date : dateList) {
    if (date.same(year, month.getMonth(), day)) {
      return true;
    }
  }

  return false;
}

7.使用表结构分离公共逻辑，避免重复（坚持DRY原则）

7.1重构前

public void testGetIntPart() throws Exception {
  assertEquals("0", digitTransform.getIntPart("0.01");
  assertEquals("1", digitTransform.getIntPart("1.2");
  assertEquals("1234", digitTransform.getIntPart("1234");
  assertEquals("1", digitTransform.getIntPart("1.01");
  assertEquals("0", digitTransform.getIntPart("0.01");
  assertEquals("11111", digitTransform.getIntPart("11111");
  assertEquals("1000", digitTransform.getIntPart("1000.11");
}

7.2重构后

public void testGetIntPart() throws Exception {
   String[][] cases = new String[][] {{"0.01","0"},{"1.2","1"},
        {"1234","1234"},{"1.01","1"},{"0","0"},
        {"11111","11111"},{"1000.11","1000"}};

   for (int i = 0, len = cases.length; i < len; i++) {
       assertEquals(cases[i][1], digitTransform.getIntPart(cases[i][0]));
   }
}

8.分离变化参数，使用格式化方法

8.1重构前

public class ExceedMaxWeekIndexOfMonthException extends
    IndexOutOfBoundsException {

  private static final long serialVersionUID = 1L;

  public ExceedMaxWeekIndexOfMonthException(String message) {
    super(message);
  }

}

8.2重构后

public class ExceedMaxWeekIndexOfMonthException extends
    IndexOutOfBoundsException {

  private static final long serialVersionUID = 1L;

  public ExceedMaxWeekIndexOfMonthException(int index, int maxCountOfWeekDay,
      Month month) {
    super(formatMessage(index, maxCountOfWeekDay, month));
  }

  private static String formatMessage(int index, int maxCountOfWeekDay,
      Month month) {
    return "Arguement index[" + index + "] exceeds max week index["
        + maxCountOfWeekDay + "] of month[" + month.toString() + "].";
  }

}

9.使用方法抽取公共逻辑

9.1重构前

public int getYear() {
  Calendar date = this.getCalendarDate();

  return date.get(Calendar.YEAR);
}

public int getMonth() {
  Calendar date = this.getCalendarDate();

  return date.get(Calendar.MONTH);
}

public int getDay() {
  Calendar date = this.getCalendarDate();

  return date.get(Calendar.DAY_OF_MONTH);
}

public int getHour() {
  Calendar date = this.getCalendarDate();

  return date.get(Calendar.HOUR_OF_DAY);
}

public int getMinute() {
  Calendar date = this.getCalendarDate();

  return date.get(Calendar.MINUTE);
}

public int getSecond() {
  Calendar date = this.getCalendarDate();

  return date.get(Calendar.SECOND);
}

public int getMillisSecond() {
  Calendar date = this.getCalendarDate();

  return date.get(Calendar.MILLISECOND);
}

9.2重构后

  private int get(int field) {
    Calendar date = this.getCalendarDate();

    return date.get(field);
  }

  public int getYear() {
    return this.get(Calendar.YEAR);
  }

  public int getMonth() {
    return this.get(Calendar.MONTH);
  }

  public int getDay() {
    return this.get(Calendar.DAY_OF_MONTH);
  }

  public int getHour() {
    return this.get(Calendar.HOUR_OF_DAY);
  }

  public int getMinute() {
    return this.get(Calendar.MINUTE);
  }

  public int getSecond() {
    return this.get(Calendar.SECOND);
  }

  public int getMillisSecond() {
    return this.get(Calendar.MILLISECOND);
  }

10.尽量使用已有的Java API

10.1重构前

protected String[] getConfigLocations() {
    String[] baseCfgs = this.getBaseCfgs();
    String[] extra = this.getExtraCfgs();
    if (extra != null && extra.length > 0) {
      int baseCfgLen = baseCfgs.length;
      int extraLen = extra.length;
      String[] cfgLocations = new String[baseCfgLen + extraLen];
      for(int i = 0; i < baseCfgLen; i++){
        cfgLocations[i] = baseCfgs[i];
      }

      for(int i = 0; i < extraLen; i++){
        cfgLocations[baseCfgLen + i] = extra[i];
      }
     
      return cfgLocations;
    } else {
      return baseCfgs;
    }
 }

10.2重构后

protected String[] getConfigLocations() {
    String[] baseCfgs = this.getBaseCfgs();
    String[] extra = this.getExtraCfgs();
    if (extra != null && extra.length > 0) {
      int baseCfgLen = baseCfgs.length;
      int extraLen = extra.length;
      String[] cfgLocations = new String[baseCfgLen + extraLen;
      System.arraycopy(baseCfgs, 0, cfgLocations, 0, baseCfgLen);
      System.arraycopy(extra, 0, cfgLocations, baseCfgLen,
          extraLen;
     
      return cfgLocations;
    } else {
      return baseCfgs;
    }
}

11.使方法通用化

11.1重构前

public DayPart[] sortDayPart() {
  if (dayParts == null || dayParts.length == 0) {
    return dayParts;
  }
  List<DayPart> dayPartList = Arrays.asList(dayParts);

  Collections.sort(dayPartList, new Comparator<DayPart>() {
    public int compare(DayPart o1, DayPart o2) {
      if (o1.getIndex() < o2.getIndex()) {
        return -1;
      } else if (o1.getIndex() > o2.getIndex()) {
        return 1;
      } else {
        return 0;
      }
    }
  });

  return dayPartList.toArray(new DayPart[dayPartList.size()]);
}

11.2重构后

public DayPart[] sortDayPart() {
  return this.sortDayPart(SortMode.ASC);
}

public DayPart[] sortDayPart(final SortMode sortMode) {
  if (dayParts == null || dayParts.length == 0) {
    return dayParts;
  }
  List<DayPart> dayPartList = Arrays.asList(dayParts);

  Collections.sort(dayPartList, new Comparator<DayPart>() {
    public int compare(DayPart o1, DayPart o2) {
      if (o1.getIndex() < o2.getIndex()) {
        return sortMode.isAsc() ? -1 : 1;
      } else if (o1.getIndex() > o2.getIndex()) {
        return sortMode.isAsc() ? 1 : -1;
      } else {
        return 0;
      }
    }
  });

  return dayPartList.toArray(new DayPart[dayPartList.size()]);
}

12.避免空语句

12.1重构前

public int getRemainMinutes(int hour, int minute) {
  int startHour = fromHour;
  int startMinute = fromMinute;
  if (this.fromAfterEqual(hour, minute)) {
    // ------from-------position------to--------
    ;//use default init value
  } else if (this.toAfterEqual(hour, minute)) {
    // ------from-------position------to--------
    startHour = hour;
    startMinute = minute;
  } else {
    // --------from-------to--------position-------
    startHour = toHour;
    startMinute = toMinute;
  }

  return this.getMinutes(startHour, startMinute, toHour, toMinute);
}

12.2重构后

public int getRemainMinutes(int hour, int minute) {
  // --------from-------to--------position-------
  int startHour = toHour;
  int startMinute = toMinute;

  if (this.fromAfterEqual(hour, minute)) {
    // ------position------from-------to--------
    startHour = fromHour;
    startMinute = fromMinute;
  } else if (this.toAfterEqual(hour, minute)) {
    // ------from-------position------to--------
    startHour = hour;
    startMinute = minute;
  }

  return this.getMinutes(startHour, startMinute, toHour, toMinute);
}

13.公共逻辑后置

13.1重构前

public int getRemainMinutes(int hour, int minute) {
  if (this.fromAfterEqual(hour, minute)) {
    // ------position------from-------to--------
    return (toHour * 60 + toMinute) - (fromHour * 60 + fromMinute);
  } else if (this.toAfterEqual(hour, minute)) {
    // ------from-------position------to--------
    return (toHour * 60 + toMinute) - (hour * 60 + minute);
  }
  else {
    // --------from-------to--------position-------
    return 0; //(toHour * 60 + toMinute) - (toHour * 60 + toMinute);
  }
}

13.2重构后

private int getMinutes(int startHour, int startMinute, int endHour, int endMinute) {
  int minutes = 0;
  minutes = (endHour * 60 + endMinute) - (startHour * 60 + startMinute);

  return minutes;
}

public int getRemainMinutes(int hour, int minute) {
  // --------from-------to--------position-------
  int startHour = toHour;
  int startMinute = toMinute;

  if (this.fromAfterEqual(hour, minute)) {
    // ------position------from-------to--------
    startHour = fromHour;
    startMinute = fromMinute;
  } else if (this.toAfterEqual(hour, minute)) {
    // ------from-------position------to--------
    startHour = hour;
    startMinute = minute;
  }

  return this.getMinutes(startHour, startMinute, toHour, toMinute);
}

14.公共逻辑前置

14.1重构前

private StringBuffer transformDialect(String intPart, String fracPart) {
  StringBuffer cn = new StringBuffer();

  if (isIntegerZero(intPart)) {
    return cn;
  }

  if (this.isFractionZero(fracPart)) {
// 无小数，增加附加信息(整)
    cn.append("元").append("整");
  } else {
// 有小数，增加附加信息(零)
    cn.append("元").append("零");
  }

  return cn;
}

14.2重构后

private StringBuffer transformDialect(String intPart, String fracPart) {
  StringBuffer cn = new StringBuffer();

  if (isIntegerZero(intPart)) {
    return cn;
  }

  cn.append("元");
  if (this.isFractionZero(fracPart)) {
// 无小数，增加附加信息(整)
    cn.append("整");
  } else {
// 有小数，增加附加信息(零)
    cn.append("零");
  }

  return cn;
}

15.使用清晰的布尔型变量替换逻辑表达式

15.1重构前

public boolean tailGreatHead(int headHour, int headMinute, int tailHour,
      int tailMinute, boolean includeEqual) {

  return ((headHour < tailHour) || ((headHour == tailHour) && ((headMinute < tailMinute) || includeEqual && (headMinute == tailMinute))));
}

15.2重构后

public boolean tailGreatHead(int headHour, int headMinute, int tailHour, int tailMinute, boolean includeEqual) {
  boolean tailGreatHeadHour = (headHour < tailHour);
  boolean tailEqualHeadHour = (headHour == tailHour);
  boolean tailGreatHeadMinute = (headMinute < tailMinute);
  boolean tailEqualHeadMinute = (headMinute == tailMinute);

  boolean tailGreatEqualHeadMinute = tailGreatHeadMinute || includeEqual && tailEqualHeadMinute;

  return (tailGreatHeadHour || (tailEqualHeadHour && tailGreatEqualHeadMinute));
}

16.减少重复计算

16.1重构前

if(list != null && list.size() > 0){
  for(int i = 0; i < list.size(); i++){
    //skip...
  }
}

16.2重构后

if(list != null){
  for(int i = 0, len = list.size(); i < len; i++){
    //skip...
  }
}

17.何时需要何时创建

17.1重构前

public static Date parseDate(String date) throws ParseException {
  SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");

  if ((date == null) || (date.equals(""))) {
    return null;
  } 
  else {
    try {
      return formatter.parse(date);
    } catch (ParseException pe) {
      throw new ParseException(pe.getMessage(), pe.getErrorOffset());
    }
  }
}

17.2重构后

public static Date parseDate(String date) throws ParseException {
  if ((date == null) || (date.equals(""))) {
    return null;
  } 
  else {
    try {
      SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
      return formatter.parse(date);
    } catch (ParseException pe) {
      throw new ParseException(pe.getMessage(), pe.getErrorOffset());
    }
  }
}

18.利用已有的计算结果

18.1重构前

public static final String DAY = "DAY";
public static final String MONTH = "MONTH";
public static final String YEAR = "YEAR";
public static final String HOUR = "HOUR";
public static final String MINUTE = "MINUTE";
public static final String SECOND = "SECOND";
public static final String WEEK = "WEEK";

public long toMilliseconds(String unit) {
  if (unit == null) {
    return 0L;
  } else if (unit.equals(SECOND)) {
    return 1 * 1000L;
  } else if (unit.equals(MINUTE)) {
    return 60 * 1000L;
  } else if (unit.equals(HOUR)) {
    return 60 * 60 * 1000L;
  } else if (unit.equals(DAY)) {
    return 24 * 60 * 60 * 1000L;
  } else if (unit.equals(WEEK)) {
    return 7 * 24 * 60 * 60 * 1000L;
  } else if (unit.equals(MONTH)) {
    return 30 * 24 * 60 * 60 * 1000L;
  } else if (unit.equals(YEAR)) {
    return 365 * 24 * 60 * 60 * 1000L;
  } else {
    return 0L;
  }
}

18.2重构后

public class Unit {
  private static final long SECOND_MILLIS = 1000;
  private static final long MINUTE_MILLIS = 60 * SECOND_MILLIS;
  private static final long HOUR_MILLIS = 60 * MINUTE_MILLIS;
  private static final long DAY_MILLIS = 24 * HOUR_MILLIS;
  private static final long WEEK_MILLIS = 7 * DAY_MILLIS;
  private static final long MONTH_MILLIS = 30 * DAY_MILLIS;
  private static final long YEAR_MILLIS = 365 * DAY_MILLIS;
  private static final long CENTURY_MILLIS = 100 * YEAR_MILLIS;

  static Map<String, Unit> units = new HashMap<String, Unit>();

  public static final Unit SECOND = new Unit(SECOND_MILLIS, "SECOND");
  public static final Unit MINUTE = new Unit(MINUTE_MILLIS, "MINUTE");
  public static final Unit HOUR = new Unit(HOUR_MILLIS, "HOUR");
  public static final Unit DAY = new Unit(DAY_MILLIS, "DAY");
  public static final Unit WEEK = new Unit(WEEK_MILLIS, "WEEK");
  public static final Unit MONTH = new Unit(MONTH_MILLIS, "MONTH");
  public static final Unit YEAR = new Unit(YEAR_MILLIS, "YEAR");
  public static final Unit CENTURY = new Unit(CENTURY_MILLIS, "CENTURY");

  static {
    units.put(SECOND.name, SECOND);
    units.put(MINUTE.name, MINUTE);
    units.put(HOUR.name, HOUR);
    units.put(DAY.name, DAY);
    units.put(WEEK.name, WEEK);
    units.put(MONTH.name, MONTH);
    units.put(YEAR.name, YEAR);
    units.put(CENTURY.name, CENTURY);
  }

  private long millis;
  private String name;

  private Unit(long millis, String name) {
    this.millis = millis;
    this.name = name;
  }

  public long getMillis() {
    return millis;
  }

  public String getName() {
    return name;
  }

  public String toString() {
    StringBuffer buffer = new StringBuffer();
    buffer.append(this.getName());
    buffer.append("[");
    buffer.append(this.getMillis());
    buffer.append("]");
    return buffer.toString();
  }
}

public long toMilliseconds(Unit unit) {
  return unit.getMillis();
}

19.替换switch结构

19.1重构前

public boolean isLeap(int year) {
  return (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0);
}

public static int getMonthDays(int year, int month) {
  int numberDays = 0;

  switch (month) {
    case 1:
    case 3:
    case 5:
    case 7:
    case 8:
    case 10:
    case 12:
      numberDays = 31;
      break;

    case 4:
    case 6:
    case 9:
    case 11:
      numberDays = 30;
      break;

    case 2:
      numberDays = isLeap(year) ? 29 : 28;
      break;
  }

  return numberDays;
}

19.2重构后

public boolean isLeap(int year) {
  return (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0);
}

private int getFebruaryDays(int year) {
  return this.isLeap(year) ? 29 : 28;
}

public int getMonthDays(int year, int month) {
  int[] months = new int[] { 31, this.getFebruaryDays(year), 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

  return months[month];
}

20.避免对参数赋值

20.1重构前

public Date getStartTime(Date date) {
  date.setMinutes(fromMinute);
  date.setDate(fromHour);
  date.setDate(fromHour);
  date.setSeconds(0);

  return date;
}

20.2重构后

public Date getStartTime(final Date date) {
  Calendar calendar = Calendar.getInstance();
  calendar.setTime(date);
  calendar.set(Calendar.HOUR_OF_DAY, fromHour);
  calendar.set(Calendar.MINUTE, fromMinute);
  calendar.set(Calendar.SECOND, 0);

  return calendar.getTime();
}

21.使用类替换类型代码

21.1重构前

public class LabelComparator implements Comparator, Serializable {

  private static final long serialVersionUID = 1L;

  public static final int ASC = 1;
  public static final int DESC = 2;

  private int sortType = ASC;

  public LabelComparator() {
  }

  public LabelComparator(int sortType) {
    this.sortType = sortType;
  }

  public int compare(Object o1, Object o2) {
    if (o1 == null && o2 == null) {
      return 0;
    }
    if (o1 == null) {
      return -1;
    }
    if (o2 == null) {
      return -1;
    }

    if (((Label) o1).getIndex() < ((Label) o2).getIndex()) {
      return (sortType == ASC) ? -1 : 1;
    } else if (((Label) o1).getIndex() > ((Label) o2).getIndex()) {
      return (sortType == ASC)  ? 1 : -1;
    } else {
      return 0;
    }
  }
}

21.2重构后

public final class SortMode implements Serializable {

  private static final long serialVersionUID = 1L;

  private static final Map<String, SortMode> INSTANCES = new HashMap<String, SortMode>();

  private final int type;
  private final String name;

  private SortMode(int type, String name) {
    this.type = type;
    this.name = name;
  }

  public String toString() {
    return name;
  }

  public static final SortMode ASC = new SortMode(1, "ASC");

  public static final SortMode DESC = new SortMode(2, "DESC");

  static {
    INSTANCES.put(ASC.name, ASC);
    INSTANCES.put(DESC.name, DESC);
  }

  public boolean isAsc() {
    return ASC.type == this.type;
  }

  public boolean isDesc() {
    return DESC.type == this.type;
  }

  private Object readResolve() {
    return INSTANCES.get(name);
  }

  public static SortMode parse(String name) {
    return (SortMode) INSTANCES.get(name);
  }
  
  public boolean equals(Object obj) {
    if (obj instanceof SortMode) {
      SortMode that = (SortMode) obj;
        if (that.type == this.type) {
          return true;
        }
        return false;
    } else {
      return false;
    }
  }
}

public class LabelComparator implements Comparator, Serializable {

  private static final long serialVersionUID = 1L;
  public SortMode mode = SortMode.ASC;

  public LabelComparator() {
  }

  public LabelComparator(SortMode mode) {
    this.mode = mode;
  }

  public int compare(Object o1, Object o2) {
    if (o1 == null && o2 == null) {
      return 0;
    }
    if (o1 == null) {
      return -1;
    }
    if (o2 == null) {
      return -1;
    }

    if (((Label) o1).getIndex() < ((Label) o2).getIndex()) {
      return mode.isAsc() ? -1 : 1;
    } else if (((Label) o1).getIndex() > ((Label) o2).getIndex()) {
      return mode.isAsc() ? 1 : -1;
    } else {
      return 0;
    }
  }
}

22.使用对象封装参数

22.1重构前

public int getRemainMinutes(int hour, int minute, int fromHour, int fromMinute, int toHour, int toMinute) {
  // --------from-------to--------position-------
  int startHour = toHour;
  int startMinute = toMinute;
  
  if (this.fromAfterEqual(hour, minute)) {
    // ------position------from-------to--------
    startHour = fromHour;
    startMinute = fromMinute;
  } else if (this.toAfterEqual(hour, minute)) {
    // ------from-------position------to--------
    startHour = hour;
    startMinute = minute;
  }

  return this.getMinutes(startHour, startMinute, toHour, toMinute);
}

22.2重构后

public class DayPart implements Serializable {

  int fromHour = -1;
  int fromMinute = -1;
  int toHour = -1;
  int toMinute = -1;

  public int getFromHour() {
    return fromHour;
  }

  public void setFromHour(int fromHour) {
    this.fromHour = fromHour;
  }

  public int getFromMinute() {
    return fromMinute;
  }

  public void setFromMinute(int fromMinute) {
    this.fromMinute = fromMinute;
  }

  public int getToHour() {
    return toHour;
  }

  public void setToHour(int toHour) {
    this.toHour = toHour;
  }

  public int getToMinute() {
    return toMinute;
  }

  public void setToMinute(int toMinute) {
    this.toMinute = toMinute;
  }
}

public int getRemainMinutes(int hour, int minute, DatePart datePart) {
  int fromHour = datePart.getFromHour();
  int fromMinute = datePart.getFromMinute();
  int toHour = datePart.getToHour();
  int toMinute = datePart.getToMinute();

  // --------from-------to--------position-------
  int startHour = toHour;
  int startMinute = toMinute;
  
  if (this.fromAfterEqual(hour, minute)) {
    // ------position------from-------to--------
    startHour = fromHour;
    startMinute = fromMinute;
  } else if (this.toAfterEqual(hour, minute)) {
    // ------from-------position------to--------
    startHour = hour;
    startMinute = minute;
  }

  return this.getMinutes(startHour, startMinute, toHour, toMinute);
}

23.封装集合操作

23.1重构前

public Class Group{

  private List<User> userList = new ArrayList<User>();

  public void setUserList(List<User> userList){
    this.userList = userList;
  }

  public List<User> getUserList(){
    return this.userList;
  }
}

23.2重构后

public Class Group{

  private List<User> userList = new ArrayList<User>();

  public void setUserList(List<User> userList){
    this.userList = userList;
  }

  public List<User> getUserList(){
    return this.userList;
  }

  public void addUser(User user){
    this.getUserList().add(user);
    user.setGroup(this);
  }

  public void removeUser(User user){
    this.getUserList().remove(user);
    user.setGroup(null);
  }
}

24.避免一次性临时变量

24.1重构前

public int countWeekDay(Month month, WeekDay weekDay) {
  int count = 0;
  int[][] weeks = this.getDates()[month.getMonth()];
    for (int week = 0, weekLen = weeks.length; week < weekLen; week++) {
      int date = weeks[week][weekDay.getDay()];
      if (date > 0) {
        count++;
      }
    }

  return count;
}

24.2重构后

public int countWeekDay(Month month, WeekDay weekDay) {
  int count = 0;
  int[][] weeks = this.getDates()[month.getMonth()];
  for (int week = 0, weekLen = weeks.length; week < weekLen; week++) {
    if (weeks[week][weekDay.getDay()] > 0) {
      count++;
    }
  }

  return count;
}

25.一个变量一种作用

25.1重构前

public IPolyDate getIndexWeekDay(Month month, int index, WeekDay weekDay) {
  int count = this.countWeekDay(month, weekDay);
  if (index > count) {
    throw new ExceedMaxWeekIndexOfMonthException("Arguement index[" + index + "] exceeds max week index[" + count + "] of month[" + month.toString() + "].");
  }

  count = 0;
  int[][] weeks = this.getDates()[month.getMonth()];
  for (int week = 0, weekLen = weeks.length; week < weekLen; week++) {
    int date = weeks[week][weekDay.getDay()];
    if (date > 0) {
      if (++count == index) {
        return new PolyDate(year, month.getMonth(), date);
      }
    }
  }

  return null;
}

25.2重构后

public IPolyDate getIndexWeekDay(Month month, int index, WeekDay weekDay) {
  int maxCountOfWeekDay = this.countWeekDay(month, weekDay);
  if (index > maxCountOfWeekDay) {
    throw new ExceedMaxWeekIndexOfMonthException("Arguement index[" + index + "] exceeds max week index["+ maxCountOfWeekDay + "] of month[" + month.toString() + "].");
  }

  int count = 0;
  int[][] weeks = this.getDates()[month.getMonth()];
  for (int week = 0, weekLen = weeks.length; week < weekLen; week++) {
    int date = weeks[week][weekDay.getDay()];
    if (date > 0) {
      if (++count == index) {
        return new PolyDate(year, month.getMonth(), date);
      }
    }
  }

  return null;
}