NoSuchElement 异常似乎无缘无故被调用
NoSuchElement Exception seems to be called for no reason
我正在尝试编写一个程序来读取数据文件，有点像这样：
01 1 2 3 4 5
02 1 2 3 4 5
03 1 2 3 4 5
等等，到目前为止我有这个代码：
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;
public class fileReader {
int lineSpaceCount; // number of spaces per line in the input
int outputSpaceCount; // number of spaces the output will use
int[] includeData; // data value places that will be included into the output
String returnText; // text that will be returned
// CONSTRUCTORS
public fileReader() {
this.lineSpaceCount = 0;
this.outputSpaceCount = 0;
this.includeData = new int[outputSpaceCount];
} // default constructor that sets everything to default values
public fileReader(final int lineSpaceCount, final int outputSpaceCount) {
this.lineSpaceCount = lineSpaceCount;
this.outputSpaceCount = outputSpaceCount;
this.includeData = new int[outputSpaceCount];
} // constructor to set everything to custom values
// SETTER METHODS
public void setIncludeData(final int[] inputArray) {
for (int i = 0; i < this.includeData.length; i++) {
this.includeData[i] = inputArray[i];
}
}
public void setOutputSpaceCount(final int outputSpaceCount) {
this.outputSpaceCount = outputSpaceCount;
}
public void setLineSpaceCount(final int lineSpaceCount) {
this.lineSpaceCount = lineSpaceCount;
}
// GETTER METHODS
public int getLineSpaceCount() {
return this.lineSpaceCount;
}
public int getOutputSpaceCount() {
return this.outputSpaceCount;
}
public int[] getIncludeData() {
return this.includeData;
}
// CUSTOM METHODS
public String splitFile(final File file) throws IOException {
int fileLength = 0;
try (
Scanner counter = new Scanner(new FileReader(file))
) {
while (counter.hasNextLine()) {
counter.nextLine();
fileLength++;
} //counts number of lines in the file
} //automatically closes the scanner
final String[] inArray = new String[fileLength]; // array that will contain every line in the file
String[] secArray = new String[this.lineSpaceCount]; // array that will contain every part of the line for inArray
try (
final Scanner input = new Scanner(file);
) {
for (int i = 0; i > -1; i++) {
inArray[i] = input.nextLine(); //this is where the NoSuchElementException happens
if (i > fileLength) {
i = -1;
} //if there are no more lines, end loop
} //puts all the lines of the file into a massive array
} //automatically closes the scanner
final String[][] outArray = new String[inArray.length][this.outputSpaceCount]; // output array that will betranslated into text, has to be placed here for the .length attribute of inArray to be correct
for (int h = 0; h < fileLength; h++) {
secArray = inArray[h].split(" "); //splits the line into portions
for (int k = 0; k < secArray.length; k++) {
outArray[h][k] = secArray[k]; // h = rows, k = columns
}
} // nested loops to transfer information into the 2D array
toText(outArray, fileLength);
return this.returnText;
} // massive method that splits a file into individual parts
public void toText(final String[][] array, final int arrayLength) {
for (int i = 0; i < arrayLength; i++) {
for (int j = 0; j < includeData.length; j++ ) {
this.returnText += array[i] [includeData[j]] + " ";
}
this.returnText += "\n";
} //method turns the 2D array into a neat output
//if includeData = {0, 2} and outArray = {{0, 2, 3}{8, 9, 14}} then returnText will equal to 0 3 \n 8 14
} //method that converts the 2D array into readable text
}
我写了一个简单的 main 方法来尝试使用文件 PovertyData.txt，打印到 output.txt。
import java.io.File;
import java.io.PrintWriter;
public class Main {
public static void main(String []args) throws Exception {
try (
PrintWriter output = new PrintWriter("outputData.txt");
) {
File povertyFile = new File("PovertyData.txt"); //importing the file
int [] includeData = {1, 3, 4, 5}; //all the data values needed for the output
fileReader readFiles = new fileReader(7, 4);
readFiles.setIncludeData(includeData);
output.println(readFiles.splitFile(povertyFile));
}
catch (java.io.IOException ex) {
System.out.println("Error: File does not exist");
}
}
}
这是 PovertyData.txt 的摘录（超过 10,000 行）
01 00190 Alabaster City School District 31754 6475 733 USSD13.txt 24NOV2014
01 00005 Albertville City School District 21522 4010 1563 USSD13.txt 24NOV2014
01 00030 Alexander City City School District 17292 2719 1158 USSD13.txt 24NOV2014
01 00060 Andalusia City School District 9044 1512 471 USSD13.txt 24NOV2014
01 00090 Anniston City School District 22759 3304 1122 USSD13.txt 24NOV2014
01 00100 Arab City School District 8238 1491 250 USSD13.txt 24NOV2014
01 00120 Athens City School District 23494 3767 770 USSD13.txt 24NOV2014
01 00180 Attalla City School District 6019 971 283 USSD13.txt 24NOV2014
01 00210 Auburn City School District 57441 7120 994 USSD13.txt 24NOV2014
01 00240 Autauga County School District 55246 10643 1855 USSD13.txt 24NOV2014
01 00270 Baldwin County School District 195540 32652 6171 USSD13.txt 24NOV2014
01 00300 Barbour County School District 14124 1769 759 USSD13.txt 24NOV2014
01 00330 Bessemer City School District 27510 4765 2009 USSD13.txt 24NOV2014
01 00360 Bibb County School District 22512 3590 1096 USSD13.txt 24NOV2014
01 00390 Birmingham City School District 212631 30718 12740 USSD13.txt 24NOV2014
01 00420 Blount County School District 51246 9201 2218 USSD13.txt 24NOV2014
01 00012 Boaz City School District 9619 1742 464 USSD13.txt 24NOV2014
01 00450 Brewton City School District 5354 866 279 USSD13.txt 24NOV2014
01 00480 Bullock County School District 10639 1565 684 USSD13.txt 24NOV2014
01 00510 Butler County School District 20265 3494 1430 USSD13.txt 24NOV2014
01 00540 Calhoun County School District 56502 9945 2162 USSD13.txt 24NOV2014
01 00600 Chambers County School District 27696 4343 1348 USSD13.txt 24NOV2014
01 00630 Cherokee County School District 26203 4163 1184 USSD13.txt 24NOV2014
01 00188 Chickasaw City School District 6120 1028 443 USSD13.txt 24NOV2014
01 00660 Chilton County School District 43951 7767 2503 USSD13.txt 24NOV2014
01 00690 Choctaw County School District 13426 2160 616 USSD13.txt 24NOV2014
01 00720 Clarke County School District 19459 3399 1146 USSD13.txt 24NOV2014
01 00750 Clay County School District 13486 2195 604 USSD13.txt 24NOV2014
01 00780 Cleburne County School District 14631 2505 637 USSD13.txt 24NOV2014
01 00810 Coffee County School District 18996 3302 719 USSD13.txt 24NOV2014
01 00840 Colbert County School District 23763 3740 947 USSD13.txt 24NOV2014
01 00870 Conecuh County School District 12887 2122 843 USSD13.txt 24NOV2014
01 00900 Coosa County School District 10898 1557 439 USSD13.txt 24NOV2014
01 00930 Covington County School District 22163 3506 745 USSD13.txt 24NOV2014
01 00960 Crenshaw County School District 13986 2350 693 USSD13.txt 24NOV2014
01 00990 Cullman City School District 14740 2313 555 USSD13.txt 24NOV2014
01 01020 Cullman County School District 66044 11111 2083 USSD13.txt 24NOV2014
01 01050 Dale County School District 15140 2540 635 USSD13.txt 24NOV2014
01 01080 Daleville City School District 11422 1883 573 USSD13.txt 24NOV2014
01 01110 Dallas County School District 22104 4098 1860 USSD13.txt 24NOV2014
01 01140 DeKalb County School District 56920 10543 2800 USSD13.txt 24NOV2014
01 01170 Decatur City School District 55850 9364 2657 USSD13.txt 24NOV2014
01 01200 Demopolis City School District 7172 1259 766 USSD13.txt 24NOV2014
01 01230 Dothan City School District 67258 11608 3349 USSD13.txt 24NOV2014
01 01260 Elba City School District 5282 830 322 USSD13.txt 24NOV2014
01 01290 Elmore County School District 73612 12654 2392 USSD13.txt 24NOV2014
01 01320 Enterprise City School District 27130 4813 1228 USSD13.txt 24NOV2014
01 01350 Escambia County School District 32629 5146 1786 USSD13.txt 24NOV2014
01 01380 Etowah County School District 60104 10265 1937 USSD13.txt 24NOV2014
01 01410 Eufaula City School District 12952 2368 924 USSD13.txt 24NOV2014
但是，在第 75 行，inArray[i] = input.nextLine();，有一个 NoSuchElement 异常，错误消息为：
Exception in thread "main" java.util.NoSuchElementException: No line found
at java.base/java.util.Scanner.nextLine(Scanner.java:1651)
at fileReader.splitFile(fileReader.java:75)
at Main.main(Main.java:15)
PovertyData.txt 的第 1651 行如下：
08 03630 Edison School District 54-JT 336 79 14 USSD13.txt 24NOV2014
我不知道为什么会这样，因为“文件”中有数据，而该语句所做的只是将文件的每一行读取到数组中。请告诉我为什么会发生这种情况或如何解决它。
谢谢。
您在读取文件时的 for 循环中存在错误。
除了修复它，还有一种更简单的方法可以从 Java.
中的文件中读取所有行
List<String> allLines = Files.readAllLines(file.toPath());
String[] inArray = new String[allLines.size()];
allLines.toArray(inArray);
我正在尝试编写一个程序来读取数据文件，有点像这样：
01 1 2 3 4 5
02 1 2 3 4 5
03 1 2 3 4 5
等等，到目前为止我有这个代码：
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;
public class fileReader {
int lineSpaceCount; // number of spaces per line in the input
int outputSpaceCount; // number of spaces the output will use
int[] includeData; // data value places that will be included into the output
String returnText; // text that will be returned
// CONSTRUCTORS
public fileReader() {
this.lineSpaceCount = 0;
this.outputSpaceCount = 0;
this.includeData = new int[outputSpaceCount];
} // default constructor that sets everything to default values
public fileReader(final int lineSpaceCount, final int outputSpaceCount) {
this.lineSpaceCount = lineSpaceCount;
this.outputSpaceCount = outputSpaceCount;
this.includeData = new int[outputSpaceCount];
} // constructor to set everything to custom values
// SETTER METHODS
public void setIncludeData(final int[] inputArray) {
for (int i = 0; i < this.includeData.length; i++) {
this.includeData[i] = inputArray[i];
}
}
public void setOutputSpaceCount(final int outputSpaceCount) {
this.outputSpaceCount = outputSpaceCount;
}
public void setLineSpaceCount(final int lineSpaceCount) {
this.lineSpaceCount = lineSpaceCount;
}
// GETTER METHODS
public int getLineSpaceCount() {
return this.lineSpaceCount;
}
public int getOutputSpaceCount() {
return this.outputSpaceCount;
}
public int[] getIncludeData() {
return this.includeData;
}
// CUSTOM METHODS
public String splitFile(final File file) throws IOException {
int fileLength = 0;
try (
Scanner counter = new Scanner(new FileReader(file))
) {
while (counter.hasNextLine()) {
counter.nextLine();
fileLength++;
} //counts number of lines in the file
} //automatically closes the scanner
final String[] inArray = new String[fileLength]; // array that will contain every line in the file
String[] secArray = new String[this.lineSpaceCount]; // array that will contain every part of the line for inArray
try (
final Scanner input = new Scanner(file);
) {
for (int i = 0; i > -1; i++) {
inArray[i] = input.nextLine(); //this is where the NoSuchElementException happens
if (i > fileLength) {
i = -1;
} //if there are no more lines, end loop
} //puts all the lines of the file into a massive array
} //automatically closes the scanner
final String[][] outArray = new String[inArray.length][this.outputSpaceCount]; // output array that will betranslated into text, has to be placed here for the .length attribute of inArray to be correct
for (int h = 0; h < fileLength; h++) {
secArray = inArray[h].split(" "); //splits the line into portions
for (int k = 0; k < secArray.length; k++) {
outArray[h][k] = secArray[k]; // h = rows, k = columns
}
} // nested loops to transfer information into the 2D array
toText(outArray, fileLength);
return this.returnText;
} // massive method that splits a file into individual parts
public void toText(final String[][] array, final int arrayLength) {
for (int i = 0; i < arrayLength; i++) {
for (int j = 0; j < includeData.length; j++ ) {
this.returnText += array[i] [includeData[j]] + " ";
}
this.returnText += "\n";
} //method turns the 2D array into a neat output
//if includeData = {0, 2} and outArray = {{0, 2, 3}{8, 9, 14}} then returnText will equal to 0 3 \n 8 14
} //method that converts the 2D array into readable text
}
我写了一个简单的 main 方法来尝试使用文件 PovertyData.txt，打印到 output.txt。
import java.io.File;
import java.io.PrintWriter;
public class Main {
public static void main(String []args) throws Exception {
try (
PrintWriter output = new PrintWriter("outputData.txt");
) {
File povertyFile = new File("PovertyData.txt"); //importing the file
int [] includeData = {1, 3, 4, 5}; //all the data values needed for the output
fileReader readFiles = new fileReader(7, 4);
readFiles.setIncludeData(includeData);
output.println(readFiles.splitFile(povertyFile));
}
catch (java.io.IOException ex) {
System.out.println("Error: File does not exist");
}
}
}
这是 PovertyData.txt 的摘录（超过 10,000 行）
01 00190 Alabaster City School District 31754 6475 733 USSD13.txt 24NOV2014
01 00005 Albertville City School District 21522 4010 1563 USSD13.txt 24NOV2014
01 00030 Alexander City City School District 17292 2719 1158 USSD13.txt 24NOV2014
01 00060 Andalusia City School District 9044 1512 471 USSD13.txt 24NOV2014
01 00090 Anniston City School District 22759 3304 1122 USSD13.txt 24NOV2014
01 00100 Arab City School District 8238 1491 250 USSD13.txt 24NOV2014
01 00120 Athens City School District 23494 3767 770 USSD13.txt 24NOV2014
01 00180 Attalla City School District 6019 971 283 USSD13.txt 24NOV2014
01 00210 Auburn City School District 57441 7120 994 USSD13.txt 24NOV2014
01 00240 Autauga County School District 55246 10643 1855 USSD13.txt 24NOV2014
01 00270 Baldwin County School District 195540 32652 6171 USSD13.txt 24NOV2014
01 00300 Barbour County School District 14124 1769 759 USSD13.txt 24NOV2014
01 00330 Bessemer City School District 27510 4765 2009 USSD13.txt 24NOV2014
01 00360 Bibb County School District 22512 3590 1096 USSD13.txt 24NOV2014
01 00390 Birmingham City School District 212631 30718 12740 USSD13.txt 24NOV2014
01 00420 Blount County School District 51246 9201 2218 USSD13.txt 24NOV2014
01 00012 Boaz City School District 9619 1742 464 USSD13.txt 24NOV2014
01 00450 Brewton City School District 5354 866 279 USSD13.txt 24NOV2014
01 00480 Bullock County School District 10639 1565 684 USSD13.txt 24NOV2014
01 00510 Butler County School District 20265 3494 1430 USSD13.txt 24NOV2014
01 00540 Calhoun County School District 56502 9945 2162 USSD13.txt 24NOV2014
01 00600 Chambers County School District 27696 4343 1348 USSD13.txt 24NOV2014
01 00630 Cherokee County School District 26203 4163 1184 USSD13.txt 24NOV2014
01 00188 Chickasaw City School District 6120 1028 443 USSD13.txt 24NOV2014
01 00660 Chilton County School District 43951 7767 2503 USSD13.txt 24NOV2014
01 00690 Choctaw County School District 13426 2160 616 USSD13.txt 24NOV2014
01 00720 Clarke County School District 19459 3399 1146 USSD13.txt 24NOV2014
01 00750 Clay County School District 13486 2195 604 USSD13.txt 24NOV2014
01 00780 Cleburne County School District 14631 2505 637 USSD13.txt 24NOV2014
01 00810 Coffee County School District 18996 3302 719 USSD13.txt 24NOV2014
01 00840 Colbert County School District 23763 3740 947 USSD13.txt 24NOV2014
01 00870 Conecuh County School District 12887 2122 843 USSD13.txt 24NOV2014
01 00900 Coosa County School District 10898 1557 439 USSD13.txt 24NOV2014
01 00930 Covington County School District 22163 3506 745 USSD13.txt 24NOV2014
01 00960 Crenshaw County School District 13986 2350 693 USSD13.txt 24NOV2014
01 00990 Cullman City School District 14740 2313 555 USSD13.txt 24NOV2014
01 01020 Cullman County School District 66044 11111 2083 USSD13.txt 24NOV2014
01 01050 Dale County School District 15140 2540 635 USSD13.txt 24NOV2014
01 01080 Daleville City School District 11422 1883 573 USSD13.txt 24NOV2014
01 01110 Dallas County School District 22104 4098 1860 USSD13.txt 24NOV2014
01 01140 DeKalb County School District 56920 10543 2800 USSD13.txt 24NOV2014
01 01170 Decatur City School District 55850 9364 2657 USSD13.txt 24NOV2014
01 01200 Demopolis City School District 7172 1259 766 USSD13.txt 24NOV2014
01 01230 Dothan City School District 67258 11608 3349 USSD13.txt 24NOV2014
01 01260 Elba City School District 5282 830 322 USSD13.txt 24NOV2014
01 01290 Elmore County School District 73612 12654 2392 USSD13.txt 24NOV2014
01 01320 Enterprise City School District 27130 4813 1228 USSD13.txt 24NOV2014
01 01350 Escambia County School District 32629 5146 1786 USSD13.txt 24NOV2014
01 01380 Etowah County School District 60104 10265 1937 USSD13.txt 24NOV2014
01 01410 Eufaula City School District 12952 2368 924 USSD13.txt 24NOV2014
但是，在第 75 行，inArray[i] = input.nextLine();，有一个 NoSuchElement 异常，错误消息为：
Exception in thread "main" java.util.NoSuchElementException: No line found
at java.base/java.util.Scanner.nextLine(Scanner.java:1651)
at fileReader.splitFile(fileReader.java:75)
at Main.main(Main.java:15)
PovertyData.txt 的第 1651 行如下：
08 03630 Edison School District 54-JT 336 79 14 USSD13.txt 24NOV2014
我不知道为什么会这样，因为“文件”中有数据，而该语句所做的只是将文件的每一行读取到数组中。请告诉我为什么会发生这种情况或如何解决它。
谢谢。
您在读取文件时的 for 循环中存在错误。 除了修复它，还有一种更简单的方法可以从 Java.
中的文件中读取所有行List<String> allLines = Files.readAllLines(file.toPath());
String[] inArray = new String[allLines.size()];
allLines.toArray(inArray);