避免滥用控制语句
函数至多有一行锁进
不要用else关键字
代码多层嵌套
if和else
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public double getEpubPrice(final boolean highQuality, final int chapterSequence) {
double price = 0;
if (highQuality && chapterSequence > START_CHARGING_SEQUENCE) {
price = 4.99;
} else if (sequenceNumber > START_CHARGING_SEQUENCE
&& sequenceNumber <= FURTHER_CHARGING_SEQUENCE) {
price = 1.99;
} else if (sequenceNumber > FURTHER_CHARGING_SEQUENCE) {
price = 2.99;
} else {
price = 0.99;
}
return price;
}
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修正：消除else，一个简单的做法就是让逻辑提前返回
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public double getEpubPrice(final boolean highQuality, final int chapterSequence) {
if (highQuality && chapterSequence > START_CHARGING_SEQUENCE) {
return 4.99;
}
if (sequenceNumber > START_CHARGING_SEQUENCE
&& sequenceNumber <= FURTHER_CHARGING_SEQUENCE) {
return 1.99;
}
if (sequenceNumber > FURTHER_CHARGING_SEQUENCE) {
return 2.99;
}
return 0.99;
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重复的switch
之所以出现重复的switch，通常是缺少了模型，重构的方式是：以多态取代表达式
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public double getBookPrice(final User user, final Book book) {
double price = book.getPrice();
switch (user.getLevel()) {
case UserLevel.SILVER:
return price * 0.9;
case UserLevel.GOLD:
return price * 0.8;
case UserLevel.PLATINUM:
return price * 0.75;
default:
return price;
}
}
public double getEpubPrice(final User user, final Epub epub) {
double price = epub.getPrice();
switch (user.getLevel()) {
case UserLevel.SILVER:
return price * 0.95;
case UserLevel.GOLD:
return price * 0.85;
case UserLevel.PLATINUM:
return price * 0.8;
default:
return price;
}
}
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修正：
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interface UserLevel {
double getBookPrice(Book book);
double getEpubPrice(Epub epub);
}
class RegularUserLevel implements UserLevel {
public double getBookPrice(final Book book) {
return book.getPrice();
}
public double getEpubPrice(final Epub epub) {
return epub.getPrice();
}
class GoldUserLevel implements UserLevel {
public double getBookPrice(final Book book) {
return book.getPrice() * 0.8;
}
public double getEpubPrice(final Epub epub) {
return epub.getPrice() * 0.85;
}
}
class SilverUserLevel implements UserLevel {
public double getBookPrice(final Book book) {
return book.getPrice() * 0.9;
}
public double getEpubPrice(final Epub epub) {
return epub.getPrice() * 0.85;
}
}
class PlatinumUserLevel implements UserLevel {
public double getBookPrice(final Book book) {
return book.getPrice() * 0.75;
}
public double getEpubPrice(final Epub epub) {
return epub.getPrice() * 0.8;
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public double getBookPrice(final User user, final Book book) {
UserLevel level = user.getUserLevel()
return level.getBookPrice(book);
}
public double getEpubPrice(final User user, final Epub epub) {
UserLevel level = user.getUserLevel()
return level.getEpubPrice(epub);
}
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