当我尝试获取输入数字时，Scanner 类的方法如何表现？

问：

我正在研究 Scanner 类的方法，只是每个站点都说了一些完全不同的东西，我感到困惑。我的疑问如下：

为什么是以下代码：

System.out.println("Enter the number of wheels: ");
do {
    if (input.hasNextInt()) {
        numeroRuote = input.nextInt();
        // verificaTipoDiDato = false;
        break;
    }
        
    else {
        System.out.println("Wrong data type for number of wheels!\Enter new number of wheels: ");
        // verificaTipoDiDato = true;
        input.next();
    }
}
while (!input.hasNextInt());

System.out.println("Enter the number of headlights: ");
do {
    if (input.hasNextInt()) {
        numeroFari = input.nextInt();
        // verificaTipoDiDato = false;
        break;
    }
    else {
        System.out.println("Incorrect data type for number of headlights!\Enter new number of headlights: ");
        // verificaTipoDiDato = true;
        input.next();
    }
}
while (!input.hasNextInt());

它这样做：

Enter the number of wheels: 
hello
Data type for the wrong number of wheels!
Enter a new number of wheels: 
hello
Data type for the wrong number of wheels!
Enter a new number of wheels: 
4  
Enter the number of headlights: 
Vehicle wheel number: 0
Number of vehicle headlights: 4

难道不应该也需要输入大灯的数量吗？

我不明白为什么。