1、将长的代码变短，将每个功能抽出来
2、将变量名规范化，取个容易看懂的名字
3、面向对象的原则，函数使用了来自哪类的信息，就应该放到那个类中。
4、查询函数方法：将涉及到该变量的代码抽出成一个函数，在需要调用改变量的地方调用该函数即可。函数取代临时变量，减少了冗长复杂的函数。
5、运用多态取代相关的条件逻辑。
/**
*
* @author Administrator
*/
public class Movie {
public static final int CHILDRENS = 2;
public static final int REGULAR = 0;
public static final int NEW_RELEASE = 1;
private String _title;
private int _priceCode;
public Movie(String _title, int _priceCode) {
this._title = _title;
this._priceCode = _priceCode;
}
public String getTitle() {
return _title;
}
public void setTitle(String _title) {
this._title = _title;
}
public int getPriceCode() {
return _priceCode;
}
public void setPriceCode(int _priceCode) {
this._priceCode = _priceCode;
}
public double getCharge(int daysRented){
double result = 0;
switch(getPriceCode()){
case Movie.REGULAR:
result +=2;
if(daysRented > 2){
result += (daysRented -2) * 1.5;
}
break;
case Movie.NEW_RELEASE:
result += daysRented * 3;
break;
case Movie.CHILDRENS:
result += 1.5;
if(daysRented > 3)
result += (daysRented - 3) * 1.5;
break;
}
return result;
}
public int getFrequentRenterPoints(int daysRented){
// add bonus for a two day new releass rental
if((getPriceCode() == Movie.NEW_RELEASE) && daysRented > 1)
return 2;
return 1;
}
}
红色部分设计条件逻辑的变量，该变量具有多态性，因此可以抽离出来，用多态来表示，不同的类型逻辑分别写到自己的类中，使代码更清晰。
/**
*
* @author Administrator
*/
abstract class Price {
abstract int getPriceCode();
abstract double getCharge(int daysRented);
public int getFrequentRenterPoints(int daysRented){
return 1;
}
}
class ChildrensPrice extends Price {
int getPriceCode() {
return Movie.CHILDRENS;
}
public double getCharge(int daysRented) {
double result = 1.5;
if (daysRented > 3) {
result += (daysRented - 3) * 1.5;
}
return result;
}
}
class NewReleasePrice extends Price {
int getPriceCode() {
return Movie.NEW_RELEASE;
}
public double getCharge(int daysRented) {
return daysRented * 3;
}
public int getFrequentRenterPoints(int daysRented){
return daysRented > 1 ? 2 : 1;
}
}
class RegularPrice extends Price {
int getPriceCode() {
return Movie.REGULAR;
}
public double getCharge(int daysRented) {
double result = 2;
if (daysRented > 2) {
result += (daysRented - 2) * 1.5;
}
return result;
}
}