得来的，需要在编程中养成一种好习惯，让写好代码成为一种习惯吧！！！！！
1、使用卫语句
在什么情况下可以使用卫语句呢，如下
public void add(Object element) {
if (!readOnly) {
int newSize = size + 1;
if (newSize > elements.length) {
Object[] newElement = new Object[elements.length + 10];
for (int i = 0; i < size; i++) {
newElements[i] = elements[i];
}
elements = newElements;
}
elements[size++] = element;
}
}使用卫语句重构后，如下
public void add(Object element) {
if (readOnly)
return;
int newSize = size + 1;
if (newSize > elements.length) {
Object[] newElement = new Object[elements.length + 10];
for (int i = 0; i < size; i++) {
newElements[i] = elements[i];
}
elements = newElements;
}
elements[size++] = element;
}这样嵌套就少了一层，降低复杂度public List getUsers(){
List users = new ArrayList<User>();
//.........
//sort by most recently registered users
Collections.sort(users, new User.UserComparatorByDescendingRegistration());
return users;
}提炼方法之后
public List getUsers(){
List users = new ArrayList<User>();
//.........
sortByMostRecentlyRegistered(users);
return users;
}三、函数结构层次单一，如下void printOwing(double amount){
printBanner();
System.out.println("name:" + _name);
System.out.println("amount" + amount);
}重构后
void printOwing(double amount){
printBanner();
printDetails(amount);
}public double getPrice(){
double basePrice = _quantity*_itemPrice;
if (basePrice > 1000){
return basePrice * 0.95;
}else{
return basePrice * 0.98;
}
}重构后代码
public double getPrice(){
if (BasePrice() > 1000){
return BasePrice() * 0.95;
}else{
return BasePrice() * 0.98;
}
}
private int BasePrice(){
return _quantity* _itemPrice;
}3、变量作用单一，如下代码的avg有两个作用，意义不明确，容易产生岐义private double calculateAverage(){
Iterator grades = clines.iterator();
double avg = 0.0;
while(grades.hasNext()){
grade = (CourseGrade)grades.next();
if(!(grade.grade == "F")){
avg = avg + grade.grade - 64;
}
}
avg = avg / clines.size();
return avg;
}4、重新组织代码，变量定义与使用的跨度不要过大，即在使用时再定义，更容易理解MARKETING_DATA *marketingData = new MARKETING_DATA;
SALES_DATA *salesData = new SALES_DATA;
TRAVEL_DATA *travelData = new TRAVEL_DATA;
travelData.ComputeQuarterly();
salesData.ComputeQuarterly();
marketingData.ComputeQuarterly();
salesData.ComputeAnnual();
marketingData.ComputeAnnual();
travelData.ComputeAnnual();
salesData.print();
travelData.print();
marketingData.print();重构后代码
MARKETING_DATA *marketingData = new MARKETING_DATA;
marketingData.ComputeQuarterly();
marketingData.ComputeAnnual();
SALES_DATA *salesData = new SALES_DATA;
salesData.ComputeQuarterly();
salesData.ComputeAnnual();
salesData.print();
TRAVEL_DATA *travelData = new TRAVEL_DATA;
travelData.ComputeQuarterly();
travelData.ComputeAnnual();
travelData.print();1、http://www.cnblogs.com/matchcolor/archive/2010/08/02/1784888.html
原文：http://blog.csdn.net/deng0zhaotai/article/details/44461879