Java最佳实践是帮助开发人员编写高效、可维护且无错误代码的指导原则。一些最佳实践包括使用有意义的变量名,遵循命名约定,编写可读和可维护的代码,最小化变量的作用域,避免魔术数字和字符串,使用try-with-resources,正确处理异常等等。
// Bad naming
int a;
void m() {}
class MyC {}
// Good naming
int age;
void printName() {}
class User {}
// 错误的命名
class my_class {
public void calculate() {
int a = 5;
}
}
// 正确的命名
class MyClass {
public void calculateValue() {
int age = 5;
}
}
// 不好的做法
int result = 5 * 2;
// 好的做法
int age = 5;
int multiplier = 2;
int result = age * multiplier;
final int MAX_SIZE = 10;
for (int i = 0; i < MAX_SIZE; i++) {
// do something
}
// 不好的做法
public void calculate() {
double taxRate = 0.25;
double result = amount * taxRate;
}
// 好的做法
public static final double TAX_RATE = 0.25;
public void calculate() {
double result = amount * TAX_RATE;
}
// 不好的做法
public void calculateTax() {
double taxRate = 0.25;
double tax = amount * taxRate;
double total = amount + tax;
}
public void calculateTotal() {
double taxRate = 0.25;
double tax = amount * taxRate;
double total = amount + tax;
}
// 好的做法
public void calculateTax() {
double taxRate = 0.25;
double tax = amount * taxRate;
return tax;
}
public void calculateTotal() {
double tax = calculateTax();
double total = amount + tax;
}
// 不好的做法
public void readFile() {
File file = new File("example.txt");
BufferedReader reader = new BufferedReader(new FileReader(file));
String line = reader.readLine();
// Do something with the line
}
// 好的做法
public void readFile() {
try {
File file = new File("example.txt");
BufferedReader reader = new BufferedReader(new FileReader(file));
String line = reader.readLine();
// Do something with the line
} catch (IOException e) {
e.printStackTrace();
}
}
// 不好的做法
public void readFile() {
BufferedReader reader = null;
try {
File file = new File("example.txt");
reader = new BufferedReader(new FileReader(file));
String line = reader.readLine();
// Do something with the line
} catch (IOException e) {
e.printStackTrace();
} finally {
reader.close();
}
}
// 好的做法
public void readFile() {
BufferedReader reader = null;
try {
File file = new File("example.txt");
reader = new BufferedReader(new FileReader(file));
String line = reader.readLine();
// Do something with the line
} catch (IOException e) {
e.printStackTrace();
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
// 不好的做法
String name = "John";
String message = "Hello, " + name + "!";
// 好的做法
String name = "John";
StringBuilder sb = new StringBuilder();
sb.append("Hello, ");
sb.append(name);
sb.append("!");
String message = sb.toString();
StringBuilder sb = new StringBuilder();
sb.append("Hello");
sb.append(" ");
sb.append("World");
String message = sb.toString();
public enum CarType {
SEDAN,
HATCHBACK,
SUV
}
try (FileInputStream fileInputStream = new FileInputStream(file)) {
// read from file
} catch (IOException e) {
// handle exception
}
import static java.lang.Math.PI;
import static java.lang.Math.pow;
double area = PI * pow(radius, 2);
public final class Person {
private final String name;
private final int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public int getAge() {
return age;
}
}
// 没有接口
class Dog {
void bark() {
System.out.println("Woof");
}
}
class Cat {
void meow() {
System.out.println("Meow");
}
}
// 使用接口
interface Animal {
void makeSound();
}
class Dog implements Animal {
@Override
void makeSound() {
System.out.println("Woof");
}
}
class Cat implements Animal {
@Override
void makeSound() {
System.out.println("Meow");
}
}
@Deprecated
public void oldMethod() {
// do something
}
@SuppressWarnings("unchecked")
List<String> list = (List<String>) new ArrayList();
public void readFromFile(String fileName) throws FileNotFoundException, IOException {
try (FileInputStream fileInputStream = new FileInputStream(fileName)) {
// read from file
}
}
public class BankAccount {
private double balance;
public double getBalance() {
return balance;
}
// 只允许存款,不允许取款
public void deposit(double amount) {
balance += amount;
}
}
// 硬编码值
if (statusCode == 200) {
// do something
}
// 常量值
private static final int HTTP_STATUS_OK = 200;
if (statusCode == HTTP_STATUS_OK) {
// do something
}
// 没有 Diamond 运算符
List<String> list = new ArrayList <String>();
// 使用 Diamond 运算符
List<String> list = new ArrayList <>();
class Parent {
void print() {
System.out.println("Parent");
}
}
class Child extends Parent {
@Override
void print() {
System.out.println("Child");
}
}
// Class
final class MyClass {}
// Method
class Parent {
final void print() {}
}
class Child extends Parent {
// Compilation error: Cannot override the final method from Parent
}
此外,通过尽量减少对象创建,使用StringBuilder进行字符串连接,以及针对特定任务使用正确的数据结构和算法来编写高效的代码也是非常重要的。代码也应该有适当的文档,并且应该使用单元测试来确保代码的正确性。
说到Java编程,一致性是关键。一致的编码风格、约定和实践使代码更易于阅读、维护和理解。通过遵循最佳实践,Java开发人员可以编写更好的代码,提高性能,并降低错误和bug的风险。
来源:medium.com/@manuchekhrdev/20-java-best-practices-7e72da91ef25
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