Use cases of variadic parameters in Java

Practical application scenarios of variable parameters in Java

1. Introduction
Variable parameters are a powerful grammatical feature in Java, which allows methods to Accepts an indefinite number of parameters. By using variable parameters, we can handle different numbers of parameters more flexibly and concisely, improving code reusability and readability. This article will introduce the practical application scenarios of variable parameters and provide specific code examples for readers' reference.

2. The definition and use of variable parameters
In Java, variable parameters are represented by using three consecutive periods (...). The variadic argument list is treated as an array, and the arguments can be accessed using traditional array operations. The following is a simple example of using variable parameters:

public void printNumbers(int... numbers) {
    for (int number : numbers) {
        System.out.println(number);
    }
}

In the above code, the printNumbers() method receives a variable parameter number, and uses a foreach loop to print the value of each parameter. When using this method, we can pass in any number of parameters, for example:

printNumbers(1, 2, 3); // 打印1、2、3
printNumbers(4, 5);    // 打印4、5

3. Practical application scenarios of variable parameters

1. Log recording
   In the log record , often requiring a different number of arguments to be passed to the logging method. Using variadic parameters can simplify code and improve readability. The following is a simple logging example:

public void log(String message, Object... args) {
    // 将日志信息和参数组合成一条完整的日志
    String logMessage = String.format(message, args);
    // 输出日志
    System.out.println(logMessage);
}

By using variable parameters, we can pass an indefinite number of parameters when calling the log() method, for example:

log("用户名：%s，密码：%s", "admin", "123456");   // 输出：用户名：admin，密码：123456
log("用户：%s 登录", "张三");                    // 输出：用户：张三 登录

2. Dynamic Array
   Using variable parameters makes it easier to create dynamic arrays. The following is a sample code for a dynamic array class:

public class DynamicArray<T> {
    private List<T> elements;
    
    public DynamicArray(T... elements) {
        this.elements = new ArrayList<>(Arrays.asList(elements));
    }
    
    public void add(T element) {
        elements.add(element);
    }
    
    public void remove(T element) {
        elements.remove(element);
    }
    
    public void print() {
        for (T element : elements) {
            System.out.println(element);
        }
    }
}

By using variable parameters, we can pass a different number of elements when creating a DynamicArray object. For example:

DynamicArray<Integer> numbers = new DynamicArray<>(1, 2, 3);
numbers.print();   // 输出：1、2、3

DynamicArray<String> names = new DynamicArray<>("Alice", "Bob");
names.print();     // 输出：Alice、Bob

4. Summary
Variable parameters are a powerful syntax feature that provides a flexible and concise way to handle different numbers of parameters. In actual development, we can use variable parameters to simplify code and improve readability, and can be applied to various scenarios, such as logging, dynamic arrays, etc. We hope that the code examples provided in this article can help readers better understand the practical application of variadic parameters.

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