我写了3个文本文件，其中包含3列Latitude, Longitude and Device_ID。每个文件具有50-100个不同的不同经度/纬度坐标和2/4 device_id之间。
我编写了从这些txt文件中读取的代码并将其打印在屏幕上。我的下一步是将此信息放入ArrayList中。我的目标是为每个文本文件获取3个ArrayLists，因此总共有9个ArrayLists。
我不知道如何创建一个可以获取数据的ArrayList？
这是我到目前为止所做的事情;
public static void main (String args []) throws FileNotFoundException
{
File textA = new File("C:/Users/Daniel Dold/Desktop/Routes/RoutesA.txt");
File textB = new File("C:/Users/Daniel Dold/Desktop/Routes/RoutesB.txt");
File textC = new File("C:/Users/Daniel Dold/Desktop/Routes/RoutesC.txt");
Scanner scannerA = new Scanner(textA);
Scanner scannerB = new Scanner(textB);
Scanner scannerC = new Scanner(textC);
int lineNumber = 1;
while(scannerA.hasNextLine())
{
String line = scannerA.nextLine();
System.out.println(line);
lineNumber ++;
}
System.out.println();
while(scannerB.hasNextLine())
{
String line = scannerB.nextLine();
System.out.println(line);
lineNumber ++;
}
System.out.println();
while(scannerC.hasNextLine())
{
String line = scannerC.nextLine();
System.out.println(line);
lineNumber ++;
}
}
打印结果是;
51.51092066 -0.14513969 430
51.51073703 -0.14553129 431
51.51059347 -0.14583707
51.51047662 -0.1461026
51.51049331 -0.14613747
51.51048997 -0.14616698
51.51040651 -0.14641106
51.51035643 -0.14649421
51.51032972 -0.14652103
51.51027296 -0.14666057
51.51022789 -0.1467517
51.51021286 -0.14695287
51.51020285 -0.14709234
51.51021119 -0.14715671
51.51039983 -0.14728009
51.51031302 -0.14770388
51.51023081 -0.14809616
51.51037396 -0.14816656
51.51053838 -0.1482477
51.51074914 -0.14835298
51.51081507 -0.14799356
51.51090271 -0.14752015
51.51114643 -0.14763012
51.5114227 -0.14775619
51.51160215 -0.14783665
51.51171149 -0.147264
51.51179829 -0.14679461
51.51195938 -0.14597654
51.51213215 -0.14510482
51.51223063 -0.14473334
51.5123045 -0.14447115
51.51207831 -0.14425389
51.51192098 -0.14410034
51.51178786 -0.14396623
51.51166058 -0.14383413
51.51149532 -0.14366381
51.51131795 -0.14348007
51.51114768 -0.14330506
51.51108133 -0.1434841
51.5109987 -0.1436866
51.51094236 -0.14381736
51.51105087 -0.1439441
51.51122406 -0.14414862
51.51129876 -0.14423512
51.51131169 -0.14427468
51.51130418 -0.14431558
51.51123699 -0.14445908
51.51112348 -0.14470249
51.5109649 -0.14504045
51.49647926 -0.11145785 428
51.49666837 -0.11155306 435
51.49686708 -0.11165432 440
51.49705494 -0.11173612
51.498177 -0.11215657
51.49827719 -0.1121968
51.49853767 -0.11243283
51.49874472 -0.11250794
51.49888665 -0.11248111
51.4992348 -0.11213779
51.50008135 -0.11133045
51.50027253 -0.11114135
51.50053885 -0.11094555
51.50085609 -0.11072829
51.50109735 -0.11061162
51.50132443 -0.11054724
51.50160827 -0.11052578
51.50174435 -0.11048287
51.50185371 -0.11040777
51.50200899 -0.1102294
51.50218096 -0.10991424
51.50235043 -0.10951861
51.50261506 -0.10873407
51.50284881 -0.10804206
51.50305 -0.10740772
51.5030717 -0.10729775
51.50320527 -0.10689139
51.50337306 -0.10640725
51.50340813 -0.10628253
51.5036018 -0.10536924
51.50370698 -0.10499373
51.50376291 -0.10474026
51.50376583 -0.1047121
51.50376333 -0.10467119
51.50374663 -0.10458469
51.50356298 -0.10458737
51.50334635 -0.10459274
51.50260672 -0.1046209
51.50251572 -0.10461688
51.5022227 -0.10462761
51.50189796 -0.10459676
51.50175353 -0.10461554
51.50147553 -0.10466248
51.50095627 -0.10468527
51.50058977 -0.10469064
51.50039943 -0.10467589
51.49902858 -0.10473221
51.49892088 -0.10472685
51.49889751 -0.10462694
51.49886954 -0.10456122
51.49879106 -0.104466
51.49874013 -0.10444119
51.49870966 -0.10443449
51.49867877 -0.10443248
51.49864788 -0.10443717
51.49861782 -0.10445192
51.49858443 -0.1044546
51.49855813 -0.10444656
51.49849468 -0.10441303
51.49834857 -0.10431379
51.49777667 -0.10360837
51.49697099 -0.1026012
51.49614942 -0.10152295
51.49600498 -0.10134056
51.49571442 -0.10100528
51.49571192 -0.10099657
51.49568228 -0.10096103
51.49566558 -0.10092817
51.49565264 -0.10086916
51.49564554 -0.10079071
51.49563218 -0.10049432
51.49561089 -0.10034613
51.49555286 -0.10014765
51.49548231 -0.10003634
51.49514625 -0.09992704
51.49508363 -0.09991228
51.49504981 -0.09991631
51.49502184 -0.09993039
51.49499345 -0.0999619
51.49478471 -0.10047689
51.49477303 -0.10056406
51.49477219 -0.10061905
51.49478388 -0.10070353
51.4949851 -0.10117158
51.49527733 -0.10182738
51.49543013 -0.1023075
51.4955967 -0.10293178
51.49573446 -0.10340653
51.49591857 -0.104006
51.49614024 -0.10471612
51.49636358 -0.10537728
51.49647588 -0.10570653
51.49655102 -0.10591037
51.49680818 -0.10646425
51.49703527 -0.10692827
51.49718389 -0.10722331
51.49724567 -0.10737888
51.49729159 -0.10750428
51.4973254 -0.10765247
51.49733 -0.1077155
51.49732749 -0.10775842
51.49733167 -0.10782949
51.49720894 -0.10850273
51.49714715 -0.10867305
51.49685827 -0.10986529
51.49652681 -0.11124663
51.50177649 -0.05012445 426
51.50210374 -0.05050666 429
51.50253617 -0.0509908 436
51.50265346 -0.05072191 443
51.50274404 -0.05055025
51.50301702 -0.05011841
51.503242 -0.04975095
51.50362768 -0.04908308
51.50409182 -0.04814565
51.50424291 -0.04773125
51.50437147 -0.0473316
51.50446955 -0.04699029
51.50449084 -0.04689507
51.50460103 -0.04640624
51.50465362 -0.04618093
51.50527135 -0.04514828
51.50535983 -0.04511878
51.50566035 -0.04506781
51.50588239 -0.04475668
51.50633816 -0.04415586
51.50670044 -0.04277721
51.50676471 -0.04252575
51.50684818 -0.04212744
51.50690328 -0.04173316
51.50692748 -0.04136502
51.50694835 -0.04037864
51.50692999 -0.03981739
51.50689117 -0.0390315
51.50687072 -0.03860503
51.50672631 -0.03755696
51.50658149 -0.03651693
51.50652598 -0.03614276
51.5064279 -0.03572434
51.50622631 -0.03506183
51.50616495 -0.03487475
51.50611278 -0.03475807
51.50605226 -0.03466084
51.50579474 -0.03435977
51.50577554 -0.03434367
51.50566744 -0.03427662
51.50522293 -0.03414184
51.50495664 -0.03413178
51.50471706 -0.0341586
51.50449835 -0.03419347
51.50445328 -0.03420688
51.5042354 -0.03416396
51.50346907 -0.03374956
51.50327456 -0.03367446
51.50285382 -0.03346659
51.5025416 -0.03336198
51.50246897 -0.03333516
51.50195556 -0.03335796
51.50168591 -0.03337539
51.50139205 -0.03335528
51.50094458 -0.03334991
51.50028338 -0.03336332
51.50020991 -0.03338881
51.50017068 -0.0334277
51.50013812 -0.0335028
51.50008886 -0.03416665
51.49998951 -0.03468163
51.49991688 -0.03483452
51.49985343 -0.03489755
51.49964805 -0.03499008
51.49957459 -0.03506921
51.49964638 -0.03540851
51.49998617 -0.03537096
51.50039024 -0.03537498
51.50086777 -0.03544472
51.50147887 -0.03558017
51.5024314 -0.03577597
51.50331964 -0.03588326
51.50394907 -0.03604553
51.50432973 -0.03622524
51.50455846 -0.03638886
51.50489153 -0.03672547
51.50502426 -0.0369253
51.50520874 -0.03726594
51.505359 -0.03759987
51.50554014 -0.03820471
51.50564031 -0.0388243
51.5056712 -0.03928296
51.50566953 -0.0402271
51.50564616 -0.04049934
51.50559357 -0.04134424
51.50553847 -0.04186727
51.50532978 -0.04298575
51.50514947 -0.04372202
51.50479303 -0.04486061
51.50411185 -0.04632242
51.50325285 -0.04770778
51.50260672 -0.04881553
51.50207577 -0.04964702
51.50185037 -0.04999302
对于很多人来说，这可能是一个简单的问题，但如果你可以帮助我，那就很好，欢呼
答案 0 :(得分：2)
GOOD LORD STOP
如果你到了管理 9个ArrayList 对象的地步，就像从文件中读取一样简单，那么你的设计就出错了。你想要每个文件3 ArrayList个？不，不，让我们采取面向对象的方法。
示例
public class Position
{
private String longitude;
private String latitude;
private String id;
public Position(String longitude, String latitude, String id) {
this.longitude = longitude;
this.latitude = latitude;
this.id = id;
}
}
当您阅读自己的价值观时，请创建一个ArrayList类型Position，然后填充它。
String longitude, latitude, id;
List<Position> positions = new ArrayList<Position>();
// Grab those values from their files
positions.add(new Position(logitude, latitude, id));
现在你有了一个更易于管理，但仍然可以改进的3 ArrayList个对象;每个文件一个。
答案 1 :(得分：0)
您可以创建ArrayList来保存每个文件的每一行，或者为文件创建3个不同的数组列表。
这样的事情：
ArrayList<String> arrayList = new ArrayList<String>();
然后要在ArrayList中添加一些东西，你应该使用add方法。
while(scannerA.hasNextLine())
{
String line = scannerA.nextLine();
arrayList.add(line);
System.out.println(line);
lineNumber ++;
}
通过阅读评论，我知道你想使用3个不同的ArrayList。 代码是一样的，只需添加3个ArrayList。 在while循环中，你应该使用一次arrayList1，第二个循环arrayList2等。
我使用了String，因为你在代码中使用它，如果你需要不同的类型，你应该更改它。
答案 2 :(得分：0)
您的Id列表需要是一个列表列表，因为您可以拥有多个ID。
因此，对于您将拥有的每个文件
List<Integer> LongList = new ArrayList<>;
List<Integer> LatList = new ArrayList<>;
List<List<Integer>> IdList = new ArrayList<>;
分割选项卡上的每一行，即
String[] parts = line.split(\t);
然后将每个部分添加到右边的'ArrayList'，即
LongList.add(Double.parseDouble(parts[0]));
LatList.add(Double.parseDouble(parts[1]));
List<Integer> ids = new ArrayList<>();
IdList.add(ids);
for(int i =2;i<parts.length;i++)
ids.add(Integer.parseInt(parts[i]));
然后你可以一起迭代它们。如果您没有ID，则IdList中会有一个空列表。
答案 3 :(得分：0)
如何使用ArrayList
声明一个arraylist
您的ArrayList很可能会填充双打。因此，要声明一个可以填充双打的ArrayList，请输入：
ArrayList<Double> list = new ArrayList<Double>();
这基本上只是说我想要创建一个arraylist并且它将充满双打
将项目添加到arraylist
这很简单。
只做list.add(Double)
马可只是打败了我。我没有删除这个，所以无论如何我都要发布它。
答案 4 :(得分：0)
您想使用3个ArrayLists存储文件行中的每个数据吗？ 目前尚不清楚为什么要这样做，因为从你的输出中我看到最后一列对于某些行是空的。我建议创建一个类来存储来自一行的数据，并将每一行解析为将添加到数组中的类的新实例。您可以将Double用于纬度和经度，并在将结果存储在ArrayList中之前解析String。
public final class FileLine {
private final String latitude;
private final String longitude;
private final String[] deviceID;
public FileLine(final String latitude, final String longitude, final String[] deviceID) {
this.latitude = latitude;
this.longitude = longitude;
this.deviceID = deviceID;
}
public String getLatitude() {
return latitude;
}
public String getLongitude() {
return longitude;
}
public String[] getDeviceID() {
return deviceID;
}
}
final ArrayList<FileLine> file1Lines = new ArrayList<FileLine>();
while(scannerA.hasNextLine())
{
final String[] line = scannerA.nextLine().split(" ");
if (line.length > 2) {
file1Lines.add(new FileLine(line[0], line[1], Arrays.copyOfRange(line, 2, line.length - 1)));
} else if (line.length == 2) {
file1Lines.add(new FileLine(line[0], line[1], null));
} else if (line.length == 1) {
file1Lines.add(new FileLine(line[0], null, null));
}
}
答案 5 :(得分：0)
使用以下行
定义字符串的数组列表List<String> list = new ArrayList<String>();
现在，您的行有两个或三个以空格分隔的值。您可以将空格用作分隔符并使用
拆分它们 while(scannerA.hasNextLine())
{
String line = scannerA.nextLine();
String[] values = line.split(" ");
}
迭代String []以获取值，并将每个值添加到使用上面给定行创建的三个数组中。