为差劲的标题表示歉意,但我不知道该如何表达我的问题。在将一些学生放入ArrayList之后,我尝试从BubbleSorter类的Student类中调用getSSN方法。如何调用特定的SSN变量。我了解为什么会发生错误,但不知道如何更改它以使其正常工作。错误消息如下:未为类型SearchandSort定义方法getSSN()。
我的学生班:
public class Student {
private String firstName, lastName;
private int SSN;
public Student(String first, String last, int ssn) {
firstName = first;
lastName = last;
SSN = ssn;
}
public String toString() {
return lastName + ", " + firstName + " " + SSN + "\t";
}
public boolean equals(Object other) {
return (lastName.equals(((Student)other).getLastName()) && firstName.equals(((Student)other).getFirstName()) && (SSN == (((Student)other).getSSN())));
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName (String lastName) {
this.lastName = lastName;
}
public int getSSN() {
return SSN;
}
public void setSSN(int SSN) {
this.SSN = SSN;
}
}
我的BubbleSorter:
import java.lang.reflect.Array;
// “On my honor, I have neither received nor given any unauthorized assistance on this examination.”
public class BubbleSorter {
public static void bubbleSort(SortandSearch Students[]) {
int lastPos;
int index;
int temp;
for (lastPos = Students.length-1; lastPos >= 0; lastPos--) {
for (index = 0; index <= lastPos - 1; index++) {
if (((Students[index]).getSSN()) - ((Students[index+1].getSSN())) > 0) {
temp = Students[index].getSSN();
Students[index].getSSN() = Students[index+1].getSSN();
Students[index+1].getSSN() = temp;
}
}
}
}
}
我的主班:
import java.util.ArrayList;
import java.util.Scanner;
public class SortandSearch {
public static void main(String[] args) {
Student a = new Student("Ryan", "Jones", 123456);
Student b = new Student("Jolie", "Decker", 123457);
ArrayList<Student> Students = new ArrayList<Student>();
Students.add(a);
Students.add(b);
System.out.println(Students);
bubbleSort(Students);
System.out.println(Students);
System.out.println("Please enter the SSN of the student you are searching for:");
Scanner scan = new Scanner(System.in);
int searchKey = scan.nextInt();
for (int index = 0; index < Students.size(); index++) {
if (Students.get(index).getSSN() == searchKey) {
System.out.print("The student with SSN " + searchKey + " is located at " + index);
}
}
}
}
编辑:
错误现在显示:表达式的类型必须是数组类型,但已解析为ArrayList。
New BubbleSorter:
import java.util.ArrayList;
// “On my honor, I have neither received nor given any unauthorized assistance on this examination.”
public class BubbleSorter {
public static void bubbleSort(ArrayList<Student> studentList) {
int lastPos;
int index;
int temp;
for (lastPos = studentList.size()-1; lastPos >= 0; lastPos--) {
for (index = 0; index <= lastPos - 1; index++) {
if ((studentList.get(index).getSSN()) - ((studentList.get(index).getSSN())) > 0) {
temp = studentList[index];
studentList[index] = studentList[index+1];
studentList[index+1] = temp;
}
}
}
}
}
此代码似乎有很多错误。我认为您正在尝试将数组列表强制转换为其他内容
首先,我认为您的功能签名应更改为
public static void bubbleSort(ArrayList<Student> studentList)
然后您可以使用以下元素访问元素:
studentList.get(index).getSSN()
在SortandSearch
中,将Student
的实例放入ArrayList <>,并且bubbleSort
方法还必须采用此类型的参数或至少为List
,然后将其转换为数组并返回排序后的列表:] >
public static List<Student> bubbleSort(List<Student> studentsList) { Student[] Students = studentsList.toArray(new Student[studentsList.size()]); // ... return Arrays.asList(Students); }
并且在调用main方法中,您需要存储排序列表:
List<Student> sorted = BubbleSorter.bubbleSort(Students);
System.out.println(sorted);