Question

我的类车中的getYear，getMake和getModel方法收到此错误消息，因为显然它们没有被传递参数。在我看来，他们正在通过论证，但我仍然是Java的初学者，所以我不确定我搞砸了。

public class NextCar {
public static final void main(String args[]) {

//Creates objects from Car class
Car c = new Car ();
Car c1 = new Car ();
Car c2 = new Car ();
Car c3 = new Car ();

//First object
//Prints mileage
c.start();
c.moveForward(6);
c.moveBackward(2);
c.moveForward(4);
System.out.println ("The car went " + c.mileage() + " miles.");

//Second object
//Prints year of car
c1.getYear(2050);
System.out.println("The year of the car is " + c1.getYear());

//Third object
//Prints year and make of car
c2.getYear(2055);
c2.getMake("Google");
System.out.println("The year of the car is " + c2.getYear() + " and the make is " + c2.getMake());

//Fourth object
//Prints year, make, and model of car
c3.getYear(2060);
c3.getMake("Google");
c3.getModel("Smart");
System.out.println("The year of the car is " + c3.getYear() + " and the make is " +    
c3.getMake() + " and the model is " + c3.getModel());

}
}

//creates Car class
class Car {
public int year = 0;
public String make = "";
public String model = "";
public int miles = 0;
public boolean power = false;

public void start() {
    power = true;
}

public void moveForward(int mf) {
    if (power == true) {
        miles += mf;
    }
}

public void moveBackward(int mb) {
    if (power == true) {
        miles -= mb;
    }
}

public int mileage() {
    return miles;
}

public int getYear(int y) {
    year = y;
    return year;
}

public String getMake(String ma) {
    make = ma;
    return make;
}

public String getModel(String mo) {
    model = mo;
    return mo;
}
}

Answer 1

您的Car类getYear方法接受整数输入：

public int getYear(int y)

但在没有提供输入的情况下，您可以多次调用

System.out.println("The year of the car is " + c1.getYear());

System.out.println("The year of the car is " + c2.getYear() + " and the make is " + c2.getMake());


System.out.println("The year of the car is " + c3.getYear() + " and the make is " +

这就是你错误的原因。

您可能需要两种方法getYear（获取年份值）和setYear（设置年份值），但您只定义了一种方法。可能这就是你所需要的：

public void setYear(int y) {
    year = y;
}


public int getYear() {
   return year;
}

Answer 2

再看看这里：

c1.getYear(2050);
System.out.println("The year of the car is " + c1.getYear());

getYear返回一个值。所以你可以做到

int year = c1.getYear(2050);
System.out.println("The year of the car is " + year);

与其他人相似。或者如Juned所说，使用合适的getter / setter

错误：类中的方法无法应用于给定类型

2 个答案: