Java Development: How to Refactor and Optimize Code

Java development: How to refactor and optimize code, specific code examples are required

Introduction:
In the process of software development, code will inevitably appear Redundancy, disorganization, and inefficiency. In order to improve the readability, maintainability and execution efficiency of the code, we need to refactor and optimize the code. This article will introduce some common refactoring and optimization techniques and provide specific code examples.

1. Code Refactoring
1. Extract Method:
Extract complex code segments into independent methods to improve the readability and reusability of the code .
Sample code:

// 重构前
public void doSomething() {
    // 大段复杂代码
}

// 重构后
public void doSomething() {
    method1();
    method2();
    method3();
}

private void method1() {
    // 简化代码
}

private void method2() {
    // 简化代码
}

private void method3() {
    // 简化代码
}

2. Extract Variable:
Extract complex expressions into meaningful variables to improve the readability and maintainability of the code.
Sample code:

// 重构前
public void calculatePrice(double quantity, double discountRate) {
    double totalPrice = quantity * (100 - discountRate) / 100;
    // 其他业务逻辑
}

// 重构后
public void calculatePrice(double quantity, double discountRate) {
    double discount = discountRate / 100;
    double totalPrice = quantity * (1 - discount);
    // 其他业务逻辑
}

3. Consolidate Conditional Expression:
Combine multiple conditional expressions into one to simplify the code logic.
Sample code:

// 重构前
public boolean validateEmail(String email) {
    if (email.endsWith(".com") || email.endsWith(".cn")) {
        if (email.contains("@")) {
            return true;
        }
    }
    return false;
}

// 重构后
public boolean validateEmail(String email) {
    return email.matches(".+@.+(\.com|\.cn)");
}

2. Code Optimization (Optimization)
1. Reduce method calls:
Avoid unnecessary method calls and reduce time and space consumption.
Sample code:

// 优化前
public void doSomething() {
    method1();
    method2();
    method3();
    // 其他业务逻辑
}

// 优化后
public void doSomething() {
    method1();
    // 其他业务逻辑
}

private void method1() {
    // 简化代码
}

2. Use StringBuilder instead of String splicing:
String objects are immutable. Each string splicing will create a new String object. Using StringBuilder can reduce memory. overhead.
Sample code:

// 优化前
public String concatenateStrings(String str1, String str2) {
    return str1 + str2;
}

// 优化后
public String concatenateStrings(String str1, String str2) {
    StringBuilder sb = new StringBuilder();
    sb.append(str1);
    sb.append(str2);
    return sb.toString();
}

3. Use efficient data structures in the collection framework:
Choosing the appropriate data structure can improve the execution efficiency of the code.
Sample code:

// 优化前
List<String> list = new ArrayList<>();

// 优化后
List<String> list = new LinkedList<>();

Conclusion:
Code refactoring and optimization are indispensable skills for programmers. Through refactoring techniques such as extracting methods, extracting variables, and merging conditional expressions, the readability and maintainability of the code can be improved. By reducing method calls and using optimization techniques such as StringBuilder, the execution efficiency of the code can be improved. In actual development, we should choose appropriate refactoring and optimization techniques according to specific situations to improve code quality and performance.

Reference: "Refactoring: Improving the Design of Existing Code" - Martin Fowler

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