我的代码存在问题。我试图从txt文件中逐行读取，然后将这些行添加到列表中。我的问题是只有文件的最后一行被添加到列表中。
这是我的扫描仪代码：
public void readFile() throws FileNotFoundException, IOException {
BufferedReader br = new BufferedReader(new FileReader(file));
String line;
while ((line = br.readLine()) != null) {
cyclistList = (List) Arrays.asList(line);
System.out.println(line);
}
br.close();
}
我可以很好地打印列表，但是当我尝试从txt文件逐行添加到列表中时，它只会添加最后一行。
这是txt文件包含的内容，也使用System.out.println方法打印出来：
[A.CONTADOR TCS ESP 00:09:48 2 45]
[A.DELAPLACE BSE FRA 03:11:28 1 15]
[A.DEMARE FDJ FRA 04:05:28 0 43]
[A.FONSECA BSE FRA 03:53:13 0 18]
[A.GENIEZ FDJ FRA 03:42:57 27 31]
[A.GERARD BSE FRA 04:02:06 0 0]
[A.GREIPEL LTS ALL 04:03:28 0 366]
[A.GRIVKO AST UKR 02:38:06 0 51]
[A.HANSEN LTS AUS 03:45:18 0 2]
[A.KRISTOFF KAT NOR 04:01:06 0 90]
[A.LOSADA KAT ESP 02:32:30 0 7]
[A.MALORI MOV ITA 03:37:28 0 11]
[A.TALANSKY TCG USA 00:22:06 22 32]
[A.TIMMER TGA HOL 04:05:30 0 0]
[A.TULIK EUC FRA 03:18:24 0 11]
[A.VALVERDE MOV ESP 00:05:25 72 103]
[A.VUILLERMOZ ALM FRA 01:28:29 2 52]
[A.YATES OGE GBR 02:16:36 17 42]
[B.COQUARD EUC FRA 03:42:36 0 152]
[B.FEILLU BSE FRA 03:23:11 0 17]
[B.HUZARSKI BOA POL 03:38:06 1 27]
[B.JUNGELS TFR LUX 01:33:21 16 76]
[B.MOLLEMA TFR HOL 00:15:14 0 38]
[B.NAULEAU EUC FRA 04:40:12 0 2]
[B.TANKINK TLJ HOL 02:30:12 0 0]
[B.VAUGRENARD FDJ FRA 03:43:08 0 20]
[C.FROOME SKY GBR 00:00:00 119 139]
[C.GAUTIER EUC FRA 01:51:51 4 54]
[C.LAPORTE COF FRA 03:59:10 0 17]
[C.RIBLON ALM FRA 02:48:19 1 23]
[D.CARUSO BMC ITA 02:26:32 8 21]
[D.CIMOLAI LAM ITA 04:33:21 0 34]
[D.GAUDIN ALM FRA 04:16:13 0 0]
[D.GRUZDEV AST KAZ 04:01:12 0 0]
[D.MARTIN TCG IRL 02:03:37 27 72]
[D.NAVARR GARCIA COF ESP 02:43:34 0 9]
[D.OSS BMC ITA 03:22:14 0 16]
[D.TEKLEHAIMANOT MTN ERY 02:16:15 8 51]
[D.VAN BAARLE TCG HOL 04:18:40 0 13]
[D.WYSS BMC SUI 02:37:17 0 0]
[E.BOASSON HAGEN MTN NOR 03:08:02 2 79]
[E.BUCHMANN BOA ALL 03:08:47 16 15]
[F.BRUN BSE FRA 04:10:32 0 18]
[F.POZZATO LAM ITA 03:58:20 1 0]
[F.SENECHAL COF FRA 04:04:06 0 -5]
[F.VACHON BSE FRA 03:15:01 0 11]
[G.CARUSO KAT ITA 03:17:03 0 1]
[G.IZAGIRRE MOV ESP 01:41:34 28 26]
[G.PREIDLER TGA AUT 03:14:14 15 14]
[G.RAST TFR SUI 03:29:00 0 0]
[G.SOUPE COF FRA 03:55:35 0 34]
[G.THOMAS SKY GBR 00:31:39 22 37]
[H.ZUBELDIA TFR ESP 02:36:50 0 0]
[I.ERVITI MOV ESP 03:47:14 0 6]
[I.STANNARD SKY GBR 03:59:37 0 0]
[J.ARREDO MORENO TFR COL 03:56:49 0 10]
[J.BAKELANTS ALM BEL 01:16:36 2 50]
[J.BARTA BOA RTC 01:26:56 20 47]
[J.CASTROVIEJO MOV ESP 01:26:05 0 31]
[J.DEBUSSCHERE LTS BEL 04:16:06 0 29]
[J.DEGENKOLB TGA ALL 03:39:43 1 298]
[J.FUGLSANG AST DAN 01:25:23 64 34]
[J.GUARNIERI KAT ITA 04:22:20 0 24]
[J.HERRADA MOV ESP 02:40:06 3 1]
[J.JANS RENSBURG MTN AFS 02:18:16 0 0]
[J.MENDES BOA POR 04:07:47 0 0]
[J.PANTANO IAM COL 01:09:08 2 48]
[J.PERAUD ALM FRA 02:35:10 0 -5]
[J.RODRIGUEZ KAT ESP 01:36:07 78 71]
[J.ROY FDJ FRA 03:32:12 6 8]
[J.SERPA PEREZ LAM COL 03:54:25 0 20]
[J.SIMON COF FRA 03:19:53 12 18]
[J.VAN EMDEN TLJ HOL 03:54:19 0 11]
[J.VERMOTE EQS BEL 03:50:32 0 0]
[K.DE KORT TGA HOL 02:57:05 0 30]
[K.DURASEK LAM CRO 03:02:14 13 26]
[K.KOREN TCG SLV 02:51:44 1 14]
[K.VANBILSEN COF BEL 04:41:27 3 37]
[L.BAK LTS DAN 01:56:57 14 9]
[L.DURBRIDGE OGE AUS 04:25:03 0 11]
[L.KONIG SKY RTC 02:53:09 0 0]
[L.MATE MARDONES COF ESP 02:10:12 0 29]
[L.ROWE SKY GBR 04:04:45 0 3]
[L.TEN DAM TLJ HOL 03:18:43 0 -5]
[L.WESTRA AST HOL 03:03:09 3 25]
[M.BONO LAM ITA 03:52:17 0 0]
[M.BRANDLE IAM AUT 04:37:36 0 9]
[M.CAVENDISH EQS GBR 04:12:05 0 206]
[M.CHEREL ALM FRA 01:05:00 24 8]
[M.ELMIGER IAM SUI 03:26:47 0 0]
[M.FRANK IAM SUI 00:15:39 4 24]
[M.GOLAS EQS POL 03:21:17 0 9]
[M.HALLER KAT AUT 03:59:04 1 13]
[M.IRIZAR TFR ESP 03:19:44 0 0]
[M.GHEBREMEDHIN MTN ERY 03:10:36 0 26]
[M.LADAGNOUS FDJ FRA 02:53:22 9 13]
[M.MATTHEWS OGE AUS 04:26:33 0 25]
[M.QUINZIATO BMC ITA 03:53:21 0 0]
[M.ROGERS TCS AUS 01:56:13 1 32]
[M.SCARPONI AST ITA 02:05:03 0 0]
[M.SCHAR BMC SUI 02:31:13 1 1]
[M.SIEBERG LTS ALL 04:24:52 0 11]
[M.TOSATTO TCS ITA 04:01:15 0 0]
[M.TRENTIN EQS ITA 03:50:59 1 44]
[M.WYSS IAM SUI 02:34:38 0 0]
[N.EDET COF FRA 03:42:42 16 34]
[N.OLIVEIRA LAM POR 02:15:32 0 10]
[N.QUINTANA MOV COL 00:01:12 108 80]
[N.ROCHE SKY IRL 01:54:08 0 16]
[P.FEDRIGO BSE FRA 02:22:54 0 37]
[P.MARTENS TLJ ALL 03:04:52 0 20]
[P.PERICHON BSE FRA 03:05:48 0 61]
[P.QUEMENEUR EUC FRA 02:57:19 0 46]
[P.ROLLAND EUC FRA 00:17:30 74 73]
[P.SAGAN TCS SLQ 02:14:55 3 432]
[P.VOSS BOA ALL 03:24:53 0 7]
[P.WEENING OGE HOL 04:15:20 0 -5]
[R.BARDET ALM FRA 00:16:00 90 74]
[R.CURVERS TGA HOL 03:35:40 0 46]
[R.DENNIS BMC AUS 03:27:34 1 36]
[R.GESINK TLJ HOL 00:10:47 32 53]
[R.HESJEDAL TCG CAN 02:04:37 41 43]
[R.HOLLENSTEIN IAM SUI 02:58:30 0 0]
[R.JANS RENSBURG MTN AFS 03:21:30 0 14]
[R.KREUZIGER TCS RTC 01:02:51 12 17]
[R.MAJKA TCS POL 01:35:06 40 28]
[R.NAVARDAUSKAS TCG LIT 04:14:40 20 44]
[R.PLAZA LAM ESP 01:38:22 11 86]
[R.PORTE SKY AUS 02:16:05 58 38]
[R.SICARD EUC FRA 01:51:32 23 32]
[R.URAN EQS COL 02:08:20 5 55]
[R.VALLS FERRI LAM ESP 03:03:11 0 5]
[S.CHAVANEL FDJ FRA 04:56:59 2 39]
[S.CLEMENT IAM HOL 02:33:42 0 37]
[S.CUMMINGS MTN GBR 03:12:23 2 49]
[S.DEVOLDER TFR BEL 04:21:31 0 0]
[S.GESCHKE TGA ALL 01:58:14 22 78]
[S.KRUIJSWIJK TLJ HOL 01:21:27 10 10]
[S.PAUWELS MTN BEL 00:31:03 55 43]
[S.SANCHEZ BMC ESP 00:22:50 0 10]
[S.TUFT OGE CAN 04:48:08 0 0]
[S.VANMARCKE TLJ BEL 03:31:15 8 5]
[S.YATES OGE GBR 03:16:04 0 40]
[T.DE GENDT LTS BEL 02:48:02 6 90]
[T.FARRAR MTN USA 04:32:32 0 12]
[T.GALLOPIN LTS FRA 01:40:44 8 85]
[T.KANGERT AST EST 01:24:58 0 0]
[T.LEEZER TLJ HOL 04:26:47 0 0]
[T.MACHADO KAT POR 02:54:31 0 0]
[T.PINOT FDJ FRA 00:38:52 82 113]
[T.VOECKLER EUC FRA 02:14:08 23 28]
[T.WELLENS LTS BEL 03:59:39 0 -1]
[V.NIBALI AST ITA 00:08:36 53 49]
[W.ANACONA MOV COL 02:31:14 33 29]
[W.BARGUIL TGA FRA 00:31:15 0 25]
[W.KELDERMAN TLJ HOL 03:04:07 1 20]
[W.POELS SKY HOL 02:12:44 18 9]
[Y.GENE EUC FRA 04:04:56 0 0]
[Z.STYBAR EQS RTC 03:30:13 0 78]
这是我使用cyclistList = (List) Arrays.asList(sc.nextLine());代码获得的输出：
[Z.STYBAR EQS RTC 03:30:13 0 78]
修改 我的坏，我忘了添加一些东西。我已经在课堂上有一个列表：
private List<RacingCyclist> cyclistList = new ArrayList<>();
此列表实现了Comparable：
public class RacingCyclist implements Comparable<RacingCyclist> {
//...
}
所以方法cyclistList.add();不起作用，因为我收到以下错误：
“没有为add（String）方法找到合适的方法 Collection.add（RacingCyclist）不适用（参数不匹配; 字符串无法转换为RacingCyclist）“
答案 0 :(得分：3)
问题是，您每次都在循环中创建新的List。
问题在于：cyclistList = (List) Arrays.asList(line);。在这一行中，您创建了一个新的List，这就是为什么您只持有最后一个元素，因为在最后一次迭代中您创建了一个只包含该元素的列表。
要解决此问题，请更改：
public void readFile() throws FileNotFoundException, IOException {
BufferedReader br = new BufferedReader(new FileReader(file));
String line;
while ((line = br.readLine()) != null) {
cyclistList = (List) Arrays.asList(line);
System.out.println(line);
}
br.close();
}
对此：
public void readFile() throws FileNotFoundException, IOException {
BufferedReader br = new BufferedReader(new FileReader(file));
String line;
ArrayList<String> list = new ArrayList<String>();
while ((line = br.readLine()) != null) {
list.add(line);
System.out.println(line);
}
br.close();
}
这样，您就可以拥有一个包含所有数据的ArrayList，而不是每次迭代都创建一个新的List。
编辑：在您的修改中，您尝试将String添加到自定义对象的ArrayList，在您的情况下为{{1} （或者这是一个自定义列表？如果是你正在尝试创建一个列表列表）。
如果这个Object可以容纳RacingCyclist，那么它应该有一个getter和一个setter，所以在你的循环中使用它们就像：
String现在，如果您的自定义对象是另一个列表（为什么？），那么它应该包含可以容纳customObject.setLine(line);
cyclistList.add(customObject);
的其他对象，或者它可以保存String本身。但我的猜测是你可能不应该这样做，使用一个简单的String而不是实现ArrayList的持有者对象，这样Comparable就可以对你进行排序元件。
第二次修改：好的，我已经对您的自定义类进行了一些修改。在这里。
<强> RacingCyclist.java
ArrayList我创建了一个空的construtor和一个名为package opg3_tour;
/**
*
* @author erso
*/
public class RacingCyclist implements Comparable<RacingCyclist> {
private String name;
private String team;
private String country;
private String time;
private int mountains;
private int points;
public RacingCyclist(String name, String team, String country, String time, int mountains, int points) {
this.name = name;
this.team = team;
this.country = country;
this.time = time;
this.mountains = mountains;
this.points = points;
}
// Empty constructor.
public RacingCyclist() { }
// Getters
public String getName() {
return name;
}
public String getTeam() {
return team;
}
public String getCountry() {
return country;
}
public String getTime() {
return time;
}
public int getMountains() {
return mountains;
}
public int getPoints() {
return points;
}
// Setters - They update the data on your Object.
public void setName(String name) {
this.name = name;
}
public void setTeam(String team) {
this.team = team;
}
public void setCountry(String country) {
this.country = country;
}
public void setTime(String time) {
this.time = time;
}
public void setMountains(int mountains) {
this.mountains = mountains;
}
public void setPoints(int points) {
this.points = points;
}
// This method parses lines on the following format: [A.CONTADOR TCS ESP 00:09:48 2 45]
public void parseLine(String str) {
str = str.replaceAll("^ +| +$| (?= )", ""); // Removing extra spaces between words.
str = str.replace("[","");
str = str.replace("]","");
String[] lines = str.split(" "); // Breaking the String into lines.
setName(lines[0]);
setTeam(lines[1]);
setCountry(lines[2]);
setTime(lines[3]);
setMountains(Integer.parseInt(lines[4]));
setPoints(Integer.parseInt(lines[5]));
}
@Override
public String toString() {
return name + " " + team + " " + country + " " + time + " " + mountains + " " + points + "\n";
}
@Override
public int compareTo(RacingCyclist o) {
if (Integer.parseInt(getTime()) > Integer.parseInt(o.getTime())){
return 1;
}
else if (Integer.parseInt(getTime()) < Integer.parseInt(o.getTime())){
return -1;
}
else {
return this.name.compareTo(o.name);
}
}
}
的方法，它可以获取您文件的那一行，并将值分配给您的自定义对象parseLine(String line)。
然后，你的循环应如下所示：
RacingCyclist这样您就可以创建while ((line = br.readLine()) != null) {
RacingCyclist obj = new RacingCyclist();
obj.parseLine(line);
cyclistList.add(obj);
System.out.println(line);
}
对象的新实例，而RacingCyclist方法会将该String断开并获取其值并将其分配给对象内部变量。< / p>
答案 1 :(得分：2)
这是因为你没有添加到列表中（使用＆＃34;添加＆＃34;方法），但始终创建一个新列表。