Question

我目前正在制作一个存储拖拉机租赁数据的程序，我在拖拉机类遇到问题，我需要覆盖toString方法打印出所有的信息。拖拉机，也是一种计算租金利润的方法，这只是出租天数*出租率，但我收到这些错误，我不知道从哪里开始。

public int RentalProfit(int RentalRate, int RentalDays)  
    {
      RentalProfit = RentalRate * RentalDays;
      return this.RentalProfit;
    }   


    @Override
    public String toString() {
        return  "Tractor (Rental days = " + RentalDays + ", Rental Rate = " + RentalRate + 
        "Rental profit = " RentalProfit + ", VehicleID = " + VehicleID ")";
    }

继承错误：

Tractor.java:59: error: ';' expected
        "Rental profit = " RentalProfit + ", VehicleID = " + VehicleID ")";
                          ^
Tractor.java:59: error: not a statement
        "Rental profit = " RentalProfit + ", VehicleID = " + VehicleID ")";
                                                           ^
Tractor.java:59: error: ';' expected
        "Rental profit = " RentalProfit + ", VehicleID = " + VehicleID ")";
                                                                      ^
3 errors



public static void main(String[] args){
          Tractor tractor;
          tractor = new Tractor();
          tractor.setRentalRate(9);
          tractor.setRentalDays(45);
          tractor.setVehicleID(9145949);
          toString();

继承人错误：

testTractor.java:11: error: non-static method toString() cannot be referenced from a static context
          toString();
          ^
1 error

Answer 1

您错过了+标志：

    return  "Tractor (Rental days = " + RentalDays + ", Rental Rate = " + RentalRate + 
    "Rental profit = " + RentalProfit + ", VehicleID = " + VehicleID + ")";
                       ^                                             ^ 
                     here                                        and here

Answer 2

在你的main方法中，你调用toString();你不能这样做 - toString不是静态方法，必须通过实例调用。你想要的是tractor.toString();

Answer 3

第一个错误你返回字符串你必须像这样关闭它

 return  ("Tractor Rental days = " + RentalDays + " Rental Rate = " + RentalRate + 
        "Rental profit = "+ RentalProfit + ", VehicleID = " + VehicleID );

在第二个问题我认为你有main方法而且它是静态的你需要使用静态方法来调用它使方法toString（）静态... 我希望我帮助你

有麻烦创造一些方法

3 个答案: