最小化Java中的可变范围：安全有效代码的最佳实践

<code class="java">public class Employee {
    // 私有类变量，限制访问权限
    private String name;
    private double salary;

    // 构造函数
    public Employee(String name, double salary) {
        this.name = name;
        this.salary = salary;
    }

    // name的getter方法（只读访问）
    public String getName() {
        return name;
    }

    // salary的getter和setter方法，包含验证逻辑
    public double getSalary() {
        return salary;
    }

    public void setSalary(double salary) {
        if (salary > 0) {
            this.salary = salary;
        } else {
            throw new IllegalArgumentException("Salary must be greater than 0.");
        }
    }

    // 提供带受控逻辑的加薪方法
    public void applyBonus(double percentage) {
        if (percentage > 0 && percentage <= 100) {
            this.salary *= (1 + percentage / 100);
        } else {
            throw new IllegalArgumentException("Bonus percentage must be between 0 and 100.");
        }
    }

    public void printDetails() {
        System.out.println("Name: " + name);
        System.out.println("Salary: $" + salary);
    }
}

public class Main {
    public static void main(String[] args) {
        // 创建Employee对象
        Employee emp = new Employee("Alice", 50000);
        System.out.println("Initial salary:");
        emp.printDetails();

        // 修改salary
        emp.setSalary(55000);
        emp.applyBonus(10);
        System.out.println("\nUpdated salary:");
        emp.printDetails();

        // 尝试设置无效的salary
        System.out.println("\nInvalid salary (-10000):");
        try {
            emp.setSalary(-10000);
        } catch (IllegalArgumentException e) {
            System.out.println(e.getMessage());
        }
    }
}</code>

<code>Initial salary:
Name: Alice
Salary: $50000.0

Updated salary:
Name: Alice
Salary: $60500.0

Invalid salary (-10000):
Salary must be greater than 0.</code>