java - ArrayList "get(i)"命令使用公共(public)类变量

Question

我正在尝试获取最长名字的长度并将其保存为 int longest，但是我的代码没有正确地从我的类(class) Student 中获取名字

这是我的代码:

public static int findLongestFirstName(ArrayList<Student> studentList) 
{
    int longest = 0;
    for (int i = 0; i < studentList.size(); i++)
        {
            if (studentList.get(i).getFirstName.length() > longest);
            {
                longest = studentList.get(i).getFirstName.length();
            }
        }
    return longest;
}

这是我获取变量的地方:

public class Student 
{
private int IDnum;
private String firstName;
private String lastName;
private int gradYear;
private double gradePoint;
public Student(int ID, String first, String last, int year, double GPA)
{
    IDnum = ID;
    firstName = first;
    lastName = last;
    gradYear = year;
    gradePoint = GPA;
}
public int getID()
{
    return IDnum;
}
public String getFirstName()
{
    return firstName;
}
public String getLastName()
{
    return lastName;
}
public int getYear()
{
    return gradYear;
}
public double getGPA()
{
    return gradePoint;
}

Answer 1

getFirstName 不是一个变量，它是一个方法。 Java 语法在调用方法时需要括号(即使该方法不带参数):

if (studentList.get(i).getFirstName().length() > longest);
                                   ^^

(在下一行)。

顺便说一句，您可以将整个 if 结构替换为:

longest = Math.max(studentList.get(i).getFirstName().length(), longest);

为了进一步简化，您可以使用 for-each 循环:

public static int findLongestFirstName(ArrayList<Student> studentList) 
{
    int longest = 0;
    for (Student student : studentList) {
        longest = Math.max(student.getFirstName().length(), longest);
    }
    return longest;
}