使用反射

使用反射可以访问和操作对象的非公共成员数据。示例代码如下：

public class MyClass { private int myPrivateField; protected int myProtectedField; int myPackageField; public int myPublicField; }

public class Main { public static void main(String[] args) throws Exception { MyClass obj = new MyClass();

    // 获取私有字段并设置值
    Field privateField = MyClass.class.getDeclaredField("myPrivateField");
    privateField.setAccessible(true);
    privateField.setInt(obj, 123);
    
    // 遍历受保护字段并输出值
    Field protectedField = MyClass.class.getDeclaredField("myProtectedField");
    protectedField.setAccessible(true);
    int protectedValue = protectedField.getInt(obj);
    System.out.println("Protected field value: " + protectedValue);
    
    // 遍历默认访问级别字段并输出值
    Field packageField = MyClass.class.getDeclaredField("myPackageField");
    packageField.setAccessible(true);
    int packageValue = packageField.getInt(obj);
    System.out.println("Package field value: " + packageValue);
}

}