泛型 <0> 是什么意思

泛型 <0> 是一种特殊的泛型类型表示法，通常用于表示一个不具体的类型参数。在某些编程语言中，泛型允许我们编写可以适用于多种类型的代码，而不需要为每种类型编写重复的代码。而 <0> 表示这个泛型类型参数没有具体的类型信息，它可以被替换为任何类型。例如，使用泛型 <0> 可以创建一个通用的容器类，可以存储任意类型的数据。

相关问题

vector<Point<T>*> vertices;什么意思

这段代码定义了一个名为 `vertices` 的变量，它是一个指向 `Point<T>` 类型指针的向量（vector）。`Point<T>` 是一个泛型类，`T` 是一个占位符，表示可以是任何;
cout << " XX" << endl;
cout << " XX" << endl;
cout << " XX" << endl;
cout << " XX" << endl;
cout << " XX" << endl;
cout << " XX" << endl;
cout << " XX" << endl;
cout << " XX" << endl;
cout << " XXXX" << endl;
cout << " XXXXXX" << endl;
cout << " XXXXXXXX" << endl;
cout << " XXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXXXXXXXXXX" << endl;
cout << " XXXXXXXXXXXX" << endl;
cout << " XXXX" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
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cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
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cout << " X" << endl;
cout << " X" << endl;
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cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
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cout << " X" << endl;
cout << " X" << endl;
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cout << " X" << endl;
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cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
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cout << " X" << endl;
cout << " X" << endl;
cout类型。这个向量中存储的是 `Point<T>` 类型的指针，而不是实际的对象。 << " X" << endl;
cout << " X" << endl;
cout << " X这意味着这个向量存储的是 `Point<T>` 对象的地址，而不是对象本身。在" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " X" << endl;
cout << " 使用时，需要先将对象动态分配内存，然后将其地址存储在 `vertices` 向量中。 X" << endl;
cout << " X" << endl;
cout << " X" << endl;
例如，可以使用类似下面的代码向 `vertices` 中添加一个 `Point<T>` 对象的指针：

    cout << "                                                                                                             X" << endl;
    cout << "                                                                                                             X" << endl;
    cout << "                                                                Point<T>* p = new Point<T>(x, y);
vertices.push_back(p);

注意，使用完毕后需要手动 X" << endl;
cout << " X" << endl;
cout << " X" << endl释放内存，以避免内存泄漏：

for (int i = 0; i < vertices.size(); i;
    cout << "                                                                                                             X" << endl;
    cout << "                                                                                                             X" << endl;
    cout << "++) {
    delete vertices[i];
}

这段代码会释放 `vertices` 向量中所有元素所指向的内存。

List<Student> studentList = new ArrayList<>();这串代码的意思

这串代码定义了一个名为 `studentList` 的泛型列表， 其中存储的元素类型为 `Student`。列表的实现采用了 `ArrayList` 类，它是 Java 集合框架中提供的一种动态数组（也称为可变数组）实现方式。在定义时，使用了 Java 7 引入的菱形语法（`<>`）来省略泛型参数的声明。

可以通过以下代码来添加一个 `Student` 对象到列表中：

Student student = new Student("张三", 20, "男");
studentList.add(student);

可以通过以下代码来访问列表中的元素：

Student firstStudent = studentList.get(0);

其中 `get(0)` 表示获取列表中第一个元素，如果列表为空则会抛出 `IndexOutOfBoundsException` 异常。如果想遍历整个列表，可以使用 `for-each` 循环：

for (Student student : studentList) {
    // 处理每个学生对象
}

`ArrayList` 还提供了其他常用的方法，如 `size()` 获取列表大小、`contains(Object o)` 判断元素是否在列表中、`indexOf(Object o)` 查找元素在列表中的位置等。