我得到迭代文本文件并将结果存储到数组列表的错误，错误发生在迭代器到达文本文件的第28行之后。
我得到的错误:
java.util.NoSuchElementException
at java.base/java.util.Scanner.throwFor(Scanner.java:937)
at java.base/java.util.Scanner.next(Scanner.java:1594)
at java.base/java.util.Scanner.nextFloat(Scanner.java:2496)
at countries.ArrayListTest.readData(ArrayListTest.java:46)
at countries.ArrayListTest.main(ArrayListTest.java:20)
[AD 42.546246 1.601554 Andorra, AE 23.424076 53.847816 United Arab Emirates, AF 33.93911 67.70995 Afghanistan, AG 17.060816 -61.79643 Antigua and Barbuda, AI 18.220554 -63.068615 Anguilla, AL 41.15333 20.168331 Albania, AM 40.0691 45.03819 Armenia, AN 12.226079 -69.06009 Netherlands Antilles, AO -11.202692 17.873886 Angola, AQ -75.25098 -0.071389 Antarctica, AR -38.416096 -63.616673 Argentina, AS -14.270972 -170.13222 American Samoa, AT 47.51623 14.550072 Austria, AU -25.274399 133.77513 Australia, AW 12.52111 -69.96834 Aruba, AZ 40.143105 47.576927 Azerbaijan, BA 43.915886 17.679075 Bosnia and Herzegovina, BB 13.193887 -59.543198 Barbados, BD 23.684994 90.35633 Bangladesh, BE 50.503887 4.469936 Belgium, BF 12.238333 -1.561593 Burkina Faso, BG 42.733883 25.48583 Bulgaria, BH 25.930414 50.63777 Bahrain, BI -3.373056 29.918886 Burundi, BJ 9.30769 2.315834 Benin, BM 32.321384 -64.75737 Bermuda, BN 4.535277 114.72767 Brunei, BO -16.290154 -63.588654 Bolivia]
28
读取文件并将对象存储在数组列表中的类:
import java.util.*;
public class ArrayListTest {
public static void main(String[] args) {
ArrayList<Country> countries = new ArrayList<Country>();
try {
readData(".//Data//CountriesGPS.txt", countries);
} catch (Exception e) {
e.printStackTrace();
}
System.out.println(countries.toString());
System.out.println(countries.size());
}
public static void readData(String fileName, ArrayList <Country> countries) throws Exception {
java.io.File file = new java.io.File(fileName);
Scanner input = new Scanner(file);
input.nextLine();
while (input.hasNext()) {
Scanner in = new Scanner(input.nextLine());
in.useDelimiter("t");
String ID = in.next();
float latitude = in.nextFloat();
float longitude = in.nextFloat();
String name = in.next();
countries.add(new Country(ID, latitude, longitude, name));
}
input.close();
}
}
应该存储在数组中的对象的类:
public class Country {
String country;
float latitude;
float longitude;
String name;
public Country(String country, float latitude, float longitude, String name) {
this.country = country;
this.latitude = latitude;
this.longitude = longitude;
this.name = name;
}
public String toString () {
//Returns a tab-separated string containing the main fields
return country + "t" + latitude + "t" + longitude + "t" + name;
}
文本文件:
country latitude longitude name
AD 42.546245 1.601554 Andorra
AE 23.424076 53.847818 United Arab Emirates
AF 33.93911 67.709953 Afghanistan
AG 17.060816 -61.796428 Antigua and Barbuda
AI 18.220554 -63.068615 Anguilla
AL 41.153332 20.168331 Albania
AM 40.069099 45.038189 Armenia
AN 12.226079 -69.060087 Netherlands Antilles
AO -11.202692 17.873887 Angola
AQ -75.250973 -0.071389 Antarctica
AR -38.416097 -63.616672 Argentina
AS -14.270972 -170.132217 American Samoa
AT 47.516231 14.550072 Austria
AU -25.274398 133.775136 Australia
AW 12.52111 -69.968338 Aruba
AZ 40.143105 47.576927 Azerbaijan
BA 43.915886 17.679076 Bosnia and Herzegovina
BB 13.193887 -59.543198 Barbados
BD 23.684994 90.356331 Bangladesh
BE 50.503887 4.469936 Belgium
BF 12.238333 -1.561593 Burkina Faso
BG 42.733883 25.48583 Bulgaria
BH 25.930414 50.637772 Bahrain
BI -3.373056 29.918886 Burundi
BJ 9.30769 2.315834 Benin
BM 32.321384 -64.75737 Bermuda
BN 4.535277 114.727669 Brunei
BO -16.290154 -63.588653 Bolivia
BR -14.235004 -51.92528 Brazil
BS 25.03428 -77.39628 Bahamas
BT 27.514162 90.433601 Bhutan
BV -54.423199 3.413194 Bouvet Island
BW -22.328474 24.684866 Botswana
BY 53.709807 27.953389 Belarus
BZ 17.189877 -88.49765 Belize
CA 56.130366 -106.346771 Canada
CC -12.164165 96.870956 Cocos [Keeling] Islands
CD -4.038333 21.758664 Congo [DRC]
CF 6.611111 20.939444 Central African Republic
CG -0.228021 15.827659 Congo [Republic]
CH 46.818188 8.227512 Switzerland
CI 7.539989 -5.54708 CÙte d'Ivoire
CK -21.236736 -159.777671 Cook Islands
CL -35.675147 -71.542969 Chile
CM 7.369722 12.354722 Cameroon
CN 35.86166 104.195397 China
CO 4.570868 -74.297333 Colombia
CR 9.748917 -83.753428 Costa Rica
CU 21.521757 -77.781167 Cuba
CV 16.002082 -24.013197 Cape Verde
CX -10.447525 105.690449 Christmas Island
CY 35.126413 33.429859 Cyprus
CZ 49.817492 15.472962 Czech Republic
DE 51.165691 10.451526 Germany
DJ 11.825138 42.590275 Djibouti
DK 56.26392 9.501785 Denmark
DM 15.414999 -61.370976 Dominica
DO 18.735693 -70.162651 Dominican Republic
DZ 28.033886 1.659626 Algeria
EC -1.831239 -78.183406 Ecuador
EE 58.595272 25.013607 Estonia
EG 26.820553 30.802498 Egypt
EH 24.215527 -12.885834 Western Sahara
ER 15.179384 39.782334 Eritrea
ES 40.463667 -3.74922 Spain
ET 9.145 40.489673 Ethiopia
FI 61.92411 25.748151 Finland
FJ -16.578193 179.414413 Fiji
FK -51.796253 -59.523613 Falkland Islands [Islas Malvinas]
FM 7.425554 150.550812 Micronesia
FO 61.892635 -6.911806 Faroe Islands
FR 46.227638 2.213749 France
GA -0.803689 11.609444 Gabon
GB 55.378051 -3.435973 United Kingdom
GD 12.262776 -61.604171 Grenada
GE 42.315407 43.356892 Georgia
GF 3.933889 -53.125782 French Guiana
GG 49.465691 -2.585278 Guernsey
GH 7.946527 -1.023194 Ghana
GI 36.137741 -5.345374 Gibraltar
GL 71.706936 -42.604303 Greenland
GM 13.443182 -15.310139 Gambia
GN 9.945587 -9.696645 Guinea
GP 16.995971 -62.067641 Guadeloupe
GQ 1.650801 10.267895 Equatorial Guinea
GR 39.074208 21.824312 Greece
GS -54.429579 -36.587909 South Georgia and the South Sandwich Islands
GT 15.783471 -90.230759 Guatemala
GU 13.444304 144.793731 Guam
GW 11.803749 -15.180413 Guinea-Bissau
GY 4.860416 -58.93018 Guyana
GZ 31.354676 34.308825 Gaza Strip
HK 22.396428 114.109497 Hong Kong
HM -53.08181 73.504158 Heard Island and McDonald Islands
HN 15.199999 -86.241905 Honduras
HR 45.1 15.2 Croatia
HT 18.971187 -72.285215 Haiti
HU 47.162494 19.503304 Hungary
ID -0.789275 113.921327 Indonesia
IE 53.41291 -8.24389 Ireland
IL 31.046051 34.851612 Israel
IM 54.236107 -4.548056 Isle of Man
IN 20.593684 78.96288 India
IO -6.343194 71.876519 British Indian Ocean Territory
IQ 33.223191 43.679291 Iraq
IR 32.427908 53.688046 Iran
IS 64.963051 -19.020835 Iceland
IT 41.87194 12.56738 Italy
JE 49.214439 -2.13125 Jersey
JM 18.109581 -77.297508 Jamaica
JO 30.585164 36.238414 Jordan
JP 36.204824 138.252924 Japan
KE -0.023559 37.906193 Kenya
KG 41.20438 74.766098 Kyrgyzstan
KH 12.565679 104.990963 Cambodia
KI -3.370417 -168.734039 Kiribati
KM -11.875001 43.872219 Comoros
KN 17.357822 -62.782998 Saint Kitts and Nevis
KP 40.339852 127.510093 North Korea
KR 35.907757 127.766922 South Korea
KW 29.31166 47.481766 Kuwait
KY 19.513469 -80.566956 Cayman Islands
KZ 48.019573 66.923684 Kazakhstan
LA 19.85627 102.495496 Laos
LB 33.854721 35.862285 Lebanon
LC 13.909444 -60.978893 Saint Lucia
LI 47.166 9.555373 Liechtenstein
LK 7.873054 80.771797 Sri Lanka
LR 6.428055 -9.429499 Liberia
LS -29.609988 28.233608 Lesotho
LT 55.169438 23.881275 Lithuania
LU 49.815273 6.129583 Luxembourg
LV 56.879635 24.603189 Latvia
LY 26.3351 17.228331 Libya
MA 31.791702 -7.09262 Morocco
MC 43.750298 7.412841 Monaco
MD 47.411631 28.369885 Moldova
ME 42.708678 19.37439 Montenegro
MG -18.766947 46.869107 Madagascar
MH 7.131474 171.184478 Marshall Islands
MK 41.608635 21.745275 Macedonia [FYROM]
ML 17.570692 -3.996166 Mali
MM 21.913965 95.956223 Myanmar [Burma]
MN 46.862496 103.846656 Mongolia
MO 22.198745 113.543873 Macau
MP 17.33083 145.38469 Northern Mariana Islands
MQ 14.641528 -61.024174 Martinique
MR 21.00789 -10.940835 Mauritania
MS 16.742498 -62.187366 Montserrat
MT 35.937496 14.375416 Malta
MU -20.348404 57.552152 Mauritius
MV 3.202778 73.22068 Maldives
MW -13.254308 34.301525 Malawi
MX 23.634501 -102.552784 Mexico
MY 4.210484 101.975766 Malaysia
MZ -18.665695 35.529562 Mozambique
NA -22.95764 18.49041 Namibia
NC -20.904305 165.618042 New Caledonia
NE 17.607789 8.081666 Niger
NF -29.040835 167.954712 Norfolk Island
NG 9.081999 8.675277 Nigeria
NI 12.865416 -85.207229 Nicaragua
NL 52.132633 5.291266 Netherlands
NO 60.472024 8.468946 Norway
NP 28.394857 84.124008 Nepal
NR -0.522778 166.931503 Nauru
NU -19.054445 -169.867233 Niue
NZ -40.900557 174.885971 New Zealand
OM 21.512583 55.923255 Oman
PA 8.537981 -80.782127 Panama
PE -9.189967 -75.015152 Peru
PF -17.679742 -149.406843 French Polynesia
PG -6.314993 143.95555 Papua New Guinea
PH 12.879721 121.774017 Philippines
PK 30.375321 69.345116 Pakistan
PL 51.919438 19.145136 Poland
PM 46.941936 -56.27111 Saint Pierre and Miquelon
PN -24.703615 -127.439308 Pitcairn Islands
PR 18.220833 -66.590149 Puerto Rico
PS 31.952162 35.233154 Palestinian Territories
PT 39.399872 -8.224454 Portugal
PW 7.51498 134.58252 Palau
PY -23.442503 -58.443832 Paraguay
QA 25.354826 51.183884 Qatar
RE -21.115141 55.536384 RÈunion
RO 45.943161 24.96676 Romania
RS 44.016521 21.005859 Serbia
RU 61.52401 105.318756 Russia
RW -1.940278 29.873888 Rwanda
SA 23.885942 45.079162 Saudi Arabia
SB -9.64571 160.156194 Solomon Islands
SC -4.679574 55.491977 Seychelles
SD 12.862807 30.217636 Sudan
SE 60.128161 18.643501 Sweden
SG 1.352083 103.819836 Singapore
SH -24.143474 -10.030696 Saint Helena
SI 46.151241 14.995463 Slovenia
SJ 77.553604 23.670272 Svalbard and Jan Mayen
SK 48.669026 19.699024 Slovakia
SL 8.460555 -11.779889 Sierra Leone
SM 43.94236 12.457777 San Marino
SN 14.497401 -14.452362 Senegal
SO 5.152149 46.199616 Somalia
SR 3.919305 -56.027783 Suriname
ST 0.18636 6.613081 S„o TomÈ and PrÌncipe
SV 13.794185 -88.89653 El Salvador
SY 34.802075 38.996815 Syria
SZ -26.522503 31.465866 Swaziland
TC 21.694025 -71.797928 Turks and Caicos Islands
TD 15.454166 18.732207 Chad
TF -49.280366 69.348557 French Southern Territories
TG 8.619543 0.824782 Togo
TH 15.870032 100.992541 Thailand
TJ 38.861034 71.276093 Tajikistan
TK -8.967363 -171.855881 Tokelau
TL -8.874217 125.727539 Timor-Leste
TM 38.969719 59.556278 Turkmenistan
TN 33.886917 9.537499 Tunisia
TO -21.178986 -175.198242 Tonga
TR 38.963745 35.243322 Turkey
TT 10.691803 -61.222503 Trinidad and Tobago
TV -7.109535 177.64933 Tuvalu
TW 23.69781 120.960515 Taiwan
TZ -6.369028 34.888822 Tanzania
UA 48.379433 31.16558 Ukraine
UG 1.373333 32.290275 Uganda
US 37.09024 -95.712891 United States
UY -32.522779 -55.765835 Uruguay
UZ 41.377491 64.585262 Uzbekistan
VA 41.902916 12.453389 Vatican City
VC 12.984305 -61.287228 Saint Vincent and the Grenadines
VE 6.42375 -66.58973 Venezuela
VG 18.420695 -64.639968 British Virgin Islands
VI 18.335765 -64.896335 U.S. Virgin Islands
VN 14.058324 108.277199 Vietnam
VU -15.376706 166.959158 Vanuatu
WF -13.768752 -177.156097 Wallis and Futuna
WS -13.759029 -172.104629 Samoa
XK 42.602636 20.902977 Kosovo
YE 15.552727 48.516388 Yemen
YT -12.8275 45.166244 Mayotte
ZA -30.559482 22.937506 South Africa
ZM -13.133897 27.849332 Zambia
ZW -19.015438 29.154857 Zimbabwe
问题似乎是由于解析文件时使用的分隔符。单独的行没有按照预期使用制表符正确分割。整行都在ID变量
中您可以尝试在数据中设置不同的分隔符。例如，我尝试了一个逗号，代码工作正常。
你的代码有很多问题:
- 您构建了许多不必要的新扫描仪对象。
- 从第一个扫描器提供的文件中读取下一行到新的扫描器中，但是不前进到新扫描器中的下一行(这将导致输出在一行中显示所有文本，每行之间使用'，'分隔符)。
- 在函数中导入类。
public static void readData(String fileName, ArrayList <Country> countries) throws Exception {
// Bad practice (import)
java.io.File file = new java.io.File(fileName);
// First scanner
Scanner input = new Scanner(file);
input.nextLine();
while (input.hasNext()) {
// New unnecessary scanner holds the next line in the file
// provided by the first scanner.
// The output will never provide the next line text in a new
// line (The scanner is'nt calling nextLine() on itself).
Scanner in = new Scanner(input.nextLine());
// --START-- The code from here works normally
in.useDelimiter("t");
String ID = in.next();
float latitude = in.nextFloat();
float longitude = in.nextFloat();
String name = in.next();
countries.add(new Country(ID, latitude, longitude, name));
// --END--
}
input.close();
}
让我帮你修改代码:
public static void readData(String fileName, ArrayList <Country> countries) throws Exception {
File file = new File(fileName);
Scanner in = new Scanner(file);
in.useDelimiter("t");
while (in.hasNextLine()) {
in.nextLine();
String ID = in.next();
float latitude = in.nextFloat();
float longitude = in.nextFloat();
String name = in.next();
countries.add(new Country(ID, latitude, longitude, name));
}
in.close();
}
最后最重要的是，确保文本文件中的每个单词实际上都使用'/t'分隔。
我只是运行代码没有任何修改，它工作得很好!我想问题出在我的笔记本电脑上。