我想弄清楚为什么每次在 for 循环中调用返回方法时我的代码都会创建一个新行。主 for 循环中的 if 语句检查名为 list 的数组列表中的每个学生对象。完成比较学生 i 和学生 j 之后(学生 j 是第二个 for 循环)。一旦 Student i 找到了最佳匹配,它应该打印出一条声明,说明他/她已经与某人匹配。
这是应该返回的内容:
Abey matches with Melissa with score 60
John matches with Jeff with score 100
Craig has no matches.
相反,它返回:
Abey matches with
Melissa with score 60
John matches with
Jeff with score 100
Craig has no matches.
代码如下:
for (int i = 0; i < list.size(); i++) {
int maxScore = 0;
int currentScore = 0;
int bestMatchScore = 0;
int bestMatchStudent = 0;
if (!list.get(i).isMatched()) {
for (int j = i; j < list.size(); j++) {
if (!list.get(j).isMatched()) {
if (j != i) {
currentScore = list.get(i).compare(list.get(j));
if (currentScore > maxScore) {
maxScore = currentScore;
bestMatchStudent = j;
bestMatchScore = maxScore;
}
}
}
}
if(bestMatchScore == 0) {
System.out.println(list.get(i).getName() + " has no matches.");
}
else {
list.get(i).setMatched(list.get(bestMatchStudent));
System.out.println(list.get(i).getName() + " matches with " + list.get(bestMatchStudent).getName() + " with score " + maxScore);
}
}
}
如果我要删除 if-else 语句中的所有 getName(),我会得到一个我想要的输出:
Student@6d3552ed matches with Student@47d77d9e with score 60
Student@147834eb matches with Student@5fda3acc with score 100
Student@704a583d has no matches.
我怀疑它与调用 getName 方法有关。它只是一个访问器方法...
这里是重现问题的所有代码:
学生类(class)
public class Student {
private String name;
private char gender;
private Date birthdate;
private Preference pref;
private boolean matched;
public Student(String name, char gender, Date birthdate, Preference pref) {
this.name = name;
this.gender = gender;
this.birthdate = birthdate;
this.pref = pref;
}
public String getName() {
return name;
}
public char getGender() {
return gender;
}
public Date getBirthdate() {
return birthdate;
}
public Preference getPref() {
return pref;
}
public boolean isMatched() {
return matched;
}
public void setMatched() {
this.matched = true;
}
public void setMatched(Student roommate) {
setMatched();
roommate.setMatched();
}
public int compare(Student st) {
if (st.getGender() != gender)
return 0;
return Math.abs((40 - pref.compare(st.getPref())) + (60 - birthdate.compare(st.getBirthdate())));
}
}
匹配类
import java.io.*;
import java.util.Scanner;
import java.util.*;
public class Match {
public static void main(String[] args) throws FileNotFoundException {
//Student[] fullRoster = new Student[5]; converted to ArrayList
ArrayList<Student> list = new ArrayList<Student>();
String fileName = "Students.txt";
Scanner input = new Scanner(new FileReader(fileName));
input.useDelimiter("[\t\r-]");
//int studentIndex = 0; converted to ArrayList
while(input.hasNext()) {
String name = input.next();
//System.out.println(name);
char gender = input.next().charAt(0);
//System.out.println(gender);
int month = Integer.parseInt(input.next());
//System.out.println(month);
int day = Integer.parseInt(input.next());
//System.out.println(day);
int year = Integer.parseInt(input.next());
//System.out.println(year);
Date birthday = new Date(year, month, day);
//System.out.println(birthday); //Printed out birthday
int pref1 = Integer.parseInt(input.next());
//System.out.println(pref1);
int pref2 = Integer.parseInt(input.next());
//System.out.println(pref2);
int pref3 = Integer.parseInt(input.next());
//System.out.println(pref3);
int pref4 = Integer.parseInt(input.next());
//System.out.println(pref4);
Preference pref = new Preference(pref1, pref2, pref3, pref4);
//System.out.println(pref); //Printed out pref
//fullRoster[studentIndex] = new Student(name, gender, birthday, pref); converted to ArrayList
list.add(new Student(name, gender, birthday, pref));
//studentIndex++; converted to ArrayList
}
input.close();
for (int i = 0; i < list.size(); i++) {
int maxScore = 0;
int currentScore = 0;
int bestMatchScore = 0;
int bestMatchStudent = 0;
if (!list.get(i).isMatched()) {
for (int j = i; j < list.size(); j++) {
if (!list.get(j).isMatched()) {
if (j != i) {
currentScore = list.get(i).compare(list.get(j));
if (currentScore > maxScore) {
maxScore = currentScore;
bestMatchStudent = j;
bestMatchScore = maxScore;
}
}
}
}
if(bestMatchScore == 0) {
System.out.println(list.get(i) + " has no matches.");
}
else {
list.get(i).setMatched(list.get(bestMatchStudent));
System.out.println(list.get(i).getName() + " matches with " + list.get(bestMatchStudent) + " with score " + maxScore);
}
}
}
}
}
偏好等级
public class Preference {
private int quietTime, music, reading, chatting;
public Preference(int quietTime, int music, int reading, int chatting) {
this.quietTime = quietTime;
this.music = music;
this.reading = reading;
this.chatting = chatting;
}
public int getQuietTime() {
return quietTime;
}
public int getMusic() {
return music;
}
public int getReading() {
return reading;
}
public int getChatting() {
return chatting;
}
public int compare(Preference pref) {
int difference = 0;
difference += Math.abs(pref.getQuietTime() - this.getQuietTime());
difference += Math.abs(pref.getMusic() - this.getMusic());
difference += Math.abs(pref.getReading() - this.getReading());
difference += Math.abs(pref.getChatting() - this.getChatting());
return difference;
}
}
日期类
public class Date {
int year, month, day;
public Date(int year, int month, int day) {
this.year = year;
this.month = month;
this.day = day;
}
public int getYear() {
return year;
}
public int getMonth() {
return month;
}
public int getDay() {
return day;
}
public int compare(Date dt) {
int yearsDifferenceInDays = (Math.abs(year - dt.getYear())) * 365;
int daysDifference = Math.abs(dt.dayOfYear() - this.dayOfYear());
int totalDifference = Math.abs(yearsDifferenceInDays - daysDifference);
int monthsDifference = totalDifference / 30;
if(monthsDifference > 60)
return 60;
return monthsDifference;
}
public int dayOfYear() {
int totalDays = 0;
switch (month) {
case 12: totalDays += 30;
case 11: totalDays += 31;
case 10: totalDays += 30;
case 9 : totalDays += 31;
case 8 : totalDays += 31;
case 7 : totalDays += 30;
case 6 : totalDays += 31;
case 5 : totalDays += 30;
case 4 : totalDays += 31;
case 3 : totalDays += 28;
case 2 : totalDays += 31;
}
totalDays += day;
return totalDays;
}
}
匹配类
import java.io.*;
import java.util.Scanner;
import java.util.*;
public class Match {
public static void main(String[] args) throws FileNotFoundException {
//Student[] fullRoster = new Student[5]; converted to ArrayList
ArrayList<Student> list = new ArrayList<Student>();
String fileName = "Students.txt";
Scanner input = new Scanner(new FileReader(fileName));
input.useDelimiter("[\t\r-]");
//int studentIndex = 0; converted to ArrayList
while(input.hasNext()) {
String name = input.next();
//System.out.println(name);
char gender = input.next().charAt(0);
//System.out.println(gender);
int month = Integer.parseInt(input.next());
//System.out.println(month);
int day = Integer.parseInt(input.next());
//System.out.println(day);
int year = Integer.parseInt(input.next());
//System.out.println(year);
Date birthday = new Date(year, month, day);
//System.out.println(birthday); //Printed out birthday
int pref1 = Integer.parseInt(input.next());
//System.out.println(pref1);
int pref2 = Integer.parseInt(input.next());
//System.out.println(pref2);
int pref3 = Integer.parseInt(input.next());
//System.out.println(pref3);
int pref4 = Integer.parseInt(input.next());
//System.out.println(pref4);
Preference pref = new Preference(pref1, pref2, pref3, pref4);
//System.out.println(pref); //Printed out pref
//fullRoster[studentIndex] = new Student(name, gender, birthday, pref); converted to ArrayList
list.add(new Student(name, gender, birthday, pref));
//studentIndex++; converted to ArrayList
}
input.close();
for (int i = 0; i < list.size(); i++) {
int maxScore = 0;
int currentScore = 0;
int bestMatchScore = 0;
int bestMatchStudent = 0;
if (!list.get(i).isMatched()) {
for (int j = i; j < list.size(); j++) {
if (!list.get(j).isMatched()) {
if (j != i) {
currentScore = list.get(i).compare(list.get(j));
if (currentScore > maxScore) {
maxScore = currentScore;
bestMatchStudent = j;
bestMatchScore = maxScore;
}
}
}
}
if(bestMatchScore == 0) {
System.out.println(list.get(i) + " has no matches.");
}
else {
list.get(i).setMatched(list.get(bestMatchStudent));
System.out.println(list.get(i).getName() + " matches with " + list.get(bestMatchStudent) + " with score " + maxScore);
}
}
}
}
}
Students.txt
Abey F 5-5-1996 0 0 0 0
John M 5-5-1997 10 10 10 10
Melissa F 5-5-1996 10 10 10 10
Craig M 5-5-1998 5 5 5 5
Jeff M 5-5-1997 10 10 10 10
最佳答案
If I were to remove all of the getName() inside the if-else statement, I get an output that is sort of what I desire:
Student@6d3552ed matches with Student@47d77d9e with score 60 Student@147834eb matches with Student@5fda3acc with score 100 Student@704a583d has no matches.
此处解释了该输出 How do I print my Java object without getting "SomeType@2f92e0f4"?
看来您只需要trim()
名称即可。
根据您希望在哪里执行“输入验证”,您可以在输入时执行此操作。
String name = input.next().trim();
或者在构造函数中
public Student(String name, char gender, Date birthdate, Preference pref) {
this.name = name.trim();
this.gender = gender;
this.birthdate = birthdate;
this.pref = pref;
}
或者在 setter/getter 中
public String getName() {
return name.trim();
}
或者当你实际在 println
或者定义toString()
,正如在另一篇文章中解释的那样return name.trim();
,然后打印list.get(i)
,就像你所做的那样。
根本问题可能是您没有将 LF (\n
) 或 CRLF (\r\n
) 定义为分隔符。
input.useDelimiter("[\t\r-]");
尝试
input.useDelimiter("\r\n|[\t\r\n-]");
关于java - 如何修复 java 中不需要的新行?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/47322031/