java - 无效的方法声明-方法新知识

我正在使用构造函数：

Donor(String lastName, String firstName, String type, int age, double minutes)

并且知道我必须将其命名为与它所在的公共类相同的名称，但是当我移动花括号使其包含在公共Donor类中时，我会遇到一些错误。

我的代码如下：

public class Program5
{
    public static void main(String args[])
    {
        Arrays.sort(Donor, new lastNameComparator());
        for (int i = 0; i < donor.length; i++)
        {
            System.out.println(Donor[i].getLastName());
        }

        Arrays.sort(Donor, new firstNameComparator());
        for (int i = 0; i < donor.length; i++)
        {
            System.out.println(Donor[i].getFirstName());
        }

        Arrays.sort(Donor, new typeComparator());
        for (int i = 0; i < donor.length; i++)
        {
            System.out.println(Donor[i].getType());
        }

        Arrays.sort(Donor, new ageComparator());
        for (int i = 0; i < donor.length; i++)
        {
            System.out.println(Donor[i].getAge());
        }

        Arrays.sort(Donor, new minutesComparator());
        for (int i = 0; i < donor.length; i++)
        {
            System.out.println(Donor[i].getMinutes());
        }
    }

    public ArrayList<Donor> donorCSVList(String filePath) throws IOException
    {
        ArrayList<Donor> list = new ArrayList<Donor>();
        Scanner scan = new Scanner(new File(filePath));
        while (scan.hasNextLine())
        {
            String line = scan.nextLine();
            String [] lineArray = line.split(",");
            list.add(new Donor(lineArray[0], lineArray[1], lineArray[2], lineArray[3], lineArray[4]));
        }
    }

    public class Donor
    {
        private String lastName;
        private String firstName;
        private String type;
        private int age;
        private double minutes;
    }

    public void Donor()
    {
        super();
        type = "Not assigned";
        age = 0;
        minutes = 0.0;

    }

    Donor(String lastName, String firstName, String type, int age, double minutes)
    {
        super(lastName, firstName);
        this.lastName = lastName;
        this.firstName = firstName;
        this.type = type;
        this.age = age;
        this.minutes = minutes;
    }

    public String getLastName()
    {
        return lastName;
    }

    public void setLastName(String lastName)
    {
        this.lastName = lastName;
    }

    public String getFirstName()
    {
        return firstName;
    }

    public void setFirstName(String firstName)
    {
        this.firstName = firstName;
    }

    public String getType()
    {
        return type;
    }

    public void setType(String type)
    {
        this.type = type;
    }

    public int getAge()
    {
        return age;
    }

    public void setAge(int age)
    {
        this.age = age;
    }

    public double setMinutes()
    {
        return minutes;
    }

    public void getMinutes(double minutes)
    {
        this.minutes = minutes;
    }

    public class lastNameComparator implements Comparator
    {
        public String compare(Donor o1, Donor o2)
        {
            String lastName1 = o1.getLastName();
            String lastName2 = o2.getLastName();
            return lastName1.compareTo(lastName2);
        }
    }

    public class firstNameComparator implements Comparator
    {
        public String compare(Donor o1, Donor o2)
        {
            String firsName1 = o1.getFirstName();
            String firstName2 = o2.getFirstName();
            return firstName1.compareTo(firstName2);
        }
    }

    public class typeComparator implements Comparator
    {

        public string compare(Donor o1, Donor o2)
        {
            String type1 = o1.getType();
            String type2 = o2.getType();
            return type1.compareTo(type2);
        }
    }

    public class ageComparator implements Comparator
    {
        public int compare(Donor o1, Date o2)
        {
            int age1 = o1.getAge();
            int age2 = o2.getAge();
            //return o2.getAge() - o1.getAge();
        }
    }

    public class minutesComparator implements Comparator
    {
        public double compare(Donor o1, Donor o2)
        {
            double minutes1 = o1.getMinutes();
            double minutes2 = o2.getMinutes();
            //return o2.getMinutes() - o1.getMinutes();
        }
    }
}

我的错误是：

Program5.java:66: error: invalid method declaration; return type required
        Donor(String lastName, String firstName, String type, int age, double minutes)

最佳答案

您的主要问题是您已将Donor类的大部分内容放错了位置。您所拥有的结构如下：

public class Donor
{
    private String lastName;
}

public String getLastName()
{
    return lastName;
}

虽然您想要的更像是这样：

public class Donor
{
    private String lastName;

    public String getLastName()
    {
        return lastName;
    }
}

该类的所有成员都必须在花括号内，该花括号界定了类的内容，而不仅仅是字段。

另外，您似乎在构造函数中使用参数调用super()，该构造函数用于没有超类且带有参数的构造函数的类。那没有道理。

最后，您可能打算公开您的Donor构造函数：

public Donor(String lastName, ...