'Key Syntax Differences in Object-Oriented Programming: Python vs. Java”

Object-oriented programming: Detailed explanation of classes and objects (Comparison of Python and Java)

This article will use Python and Java code examples to compare and explain the concepts of classes and objects, as well as the usage of constructors.

1. Classes and Objects

Python:

<code class="language-python"># Student 类定义
class Student:
    name = "Momo"

# 创建 Student 类的对象 s1
s1 = Student()
print(s1.name) </code>

Java:

<code class="language-java">// Student 类定义
class Student {
    String name = "Momo";
}

// 主类，用于测试 Student 类
public class Main {
    public static void main(String[] args) {
        // 创建 Student 类的对象 s1
        Student s1 = new Student();
        System.out.println(s1.name);
    }
}</code>

In the above code, Student is the class, and s1 is the instantiated object of the class. Both Python and Java define classes through the class keyword, and create objects in slightly different ways: Python uses = direct assignment, and Java uses the new keyword.

2. Constructor

The constructor is used to initialize the properties of an object when it is created.

Python:

<code class="language-python">class Student:
    def __init__(self, fullname):  # 构造函数
        self.name = fullname

s1 = Student("Momo")
print(s1.name)</code>

Java:

<code class="language-java">// Student 类定义
class Student {
    String name; // 实例变量

    // 构造函数
    public Student(String fullname) {
        this.name = fullname;
    }
}

// 主类，用于测试 Student 类
public class Main1 {
    public static void main(String[] args) {
        // 创建 Student 类的对象 s1
        Student s1 = new Student("Momo");
        // 打印名字
        System.out.println(s1.name);
    }
}</code>

Python’s constructor is the __init__ method, and Java’s constructor has the same name as the class. The function of both is to initialize property values ​​​​for objects. In Java, instance variables need to be explicitly declared name, while in Python, values ​​are assigned directly in __init__.

Through the above comparison, we can see that there are subtle syntax differences between Python and Java in the implementation of classes, objects, and constructors, but the core concepts are the same, and they are both basic components of object-oriented programming.

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