Question

我在第一个嵌套的if语句中得到了非法的类型错误启动，看了类似的问题我明白这通常是由错位的括号引起的，但是，我看不到一个。有人可以帮忙吗？

public class Journey
{
    private int date;
    private double time;
    private int busNumber;
    private int journeyType;
    public static double dayCharge;
    public static final double maxDayCharge = 3.50;
    public static double weekCharge;
    public static final double maxWeekCharge = 15;
    public static double monthCharge;
    public static final double maxMonthCharge = 48;
    private int journeyId;
    private static int numberOfJourneys;
    private double costOfJourney; 

    public int getDate(){
        return date;
    }  
    public Double getTime(){
        return time;
    }
    public int getBusNumber(){
        return busNumber;
    }
    public double journeyCost(journey reqJourney){ 
        if (journeyType = 1){                      //this is where the error occurs
            if (dayCharge =< 2.50)
            {
                costOfJourney = 1;
            }
            else 
            {
                costOfJourney = maxDayCharge-dayCharge;
            }

        }
        else if (journeyType = 2)
        {
            if (dayCharge =< 1.80)
            {
                costOfJourney = 1.70;
            }
            else 
            {
                costOfJourney = maxDayCharge-dayCharge;
            }
        }
        else if (journeyType = 3)
        {
            if (dayCharge =< 1.60)
            {
                costOfJourney = 1.90;
            }
            else 
            {
                costOfJourney = maxDayCharge-dayCharge;
            }

        }          
        return costOfJourney;    
    }
    public boolean isInSequence(journey reqJourney){
        journey prevJourney = jArray.get(jArray.size()-1);
        if (prevJourney.date > reqJourney.date)
        {
            return false;
        }

    }
}

Answer 1

您需要使用==来测试相等性。 =是赋值运算符。

Oracle有很好的tutorial docs解释Java运算符。

在相关的说明中，Object.equals()和==之间也存在重要区别，其他Stack Overflow问题（如this one）中详细介绍了这一点。但是，在比较您正在进行的原始类型时，==就是您想要的。

Answer 2

应该是：

 if (journeyType == 1){

if块中的表达式应始终导致布尔值（true（或）false）。

Java非法启动类型错误

2 个答案: