Question

我在理解构造函数时遇到困难，尽管对它们进行了研究，但是我们非常感谢一些帮助和解释。

我的目标是让用户为汽车输入“make”和“model”，我想在构造函数中为每个变量分配输入，后来又有三辆不同的汽车。

如何正确有效地设置分配给用户输入的“make”变量，并且可以使用构造函数访问该变量。这是非常基本的，但是我很难编写代码。

package cartest;

import java.util.Scanner;

public class CarTest 
//make, model, year, price, color, size
//default constructor
//property assignment constructor
//enter three diferent cars and display final information
//toString() method and a method to honk the horn
{
    String make;
    String model;
    int year;
    int price;
    String color;
    String size;

    public CarTest()
    {

    }

    void setMake(String make)
    {
        Scanner scanner = new Scanner (System.in);
        System.out.println("Please enter a make:");
        make = scanner.nextLine();
    }

    void getMake()
    {
        System.out.println("Selected make: " + make);
    }
    void setModel(String model)
    {
        Scanner scanner = new Scanner (System.in);
        System.out.println("Please enter a model:");
        model = scanner.nextLine();
    }



    public static void main(String[] args) 
    {

        CarTest carOne = new CarTest(); 
        carOne.getMake();



    }


}

Answer 1

我的目标是让用户输入＆＃34; make＆＃34;和＆＃34;模型＆＃34;对于一辆车，我想在构造函数中为每个变量赋值，后来有三辆不同的汽车。

我已经修改了你的课程，如下：

class CarTest {
    private String make;
    private String model;
    private int year;
    private int price;
    private String color;
    private String size;

    public CarTest() {
        this.make = "somevalue";
        this.model = "somevalue";
        this.year = 2017;
        this.price = 50000;
        this.color = "somecolor";
        this.size = "somesize";
    }

    public CarTest(String make, String model){
        this.make = make;
        this.model = model;
    }


    public String getMake() {
       return make;
    }

    public void setMake(String make) {
       this.make = make;
    }

    public String getModel() {
       return model;
    }

    public void setModel(String model) {
       this.model = model;
    }

    public int getYear() {
       return year;
    }

    public void setYear(int year) {
       this.year = year;
    }

    public int getPrice() {
       return price;
    }

    public void setPrice(int price) {
       this.price = price;
    }

    public String getColor() {
       return color;
    }

    public void setColor(String color) {
       this.color = color;
    }

    public String getSize() {
       return size;
    }

    public void setSize(String size) {
       this.size = size;
    }

    @Override
    public String toString() {
    return "CarTest{" +
            "make='" + make + '\'' +
            ", model='" + model + '\'' +
            ", year=" + year +
            ", price=" + price +
            ", color='" + color + '\'' +
            ", size='" + size + '\'' +
            '}';
    }
}

你可以看到有一个默认构造函数，你可以在其中指定对象的默认值，还有一个构造函数，它带有2个参数，允许你在对象上设置make和model如果您认为有必要，可以扩展参数。

我建议将main方法分成不同的类，让它执行此功能：

public static void main(String[] args) {
      Scanner scanner = new Scanner (System.in);
      System.out.println("Please enter a model:");
      String model = scanner.nextLine(); // validate if you need to
      System.out.println("please enter a make");
      String make = scanner.nextLine();  // validate if you need to
      CarTest carOne = new CarTest(make,model); // pass the entered details to the carOne object
      System.out.println(carOne.getMake()); // will display the value of make that has been entered
}

我为你完成了这项任务的一半：

//make, model, year, price, color, size
//default constructor
//property assignment constructor
//enter three diferent cars and display final information
//toString() method and a method to honk the horn

您只需要在我提供的解决方案中添加一些额外的代码，然后您就可以了。

在java

1 个答案: