Java 使用终端的数组索引超出范围
Array Index out of bounds for Java using terminal
我在尝试使用 java 创建的票务系统时遇到问题。我正在尝试利用两个文件来读取和写入我的输入。我目前只使用 salesSell 方法进行测试。我正在使用终端传递参数。我遇到的问题是抛出的 arrayoutofbounds 异常。
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0 at cisc_327_frontend.Frontend_try1.main(Frontend_try1.java:763)
我传递的两个数组参数是从我当前事件文件中的同一行解析而来的。文件中一行的示例是："testevent1__________0003"。我似乎无法弄清楚我在哪里遇到这个问题。任何类型的指导将不胜感激。
package cisc_327_frontend;
import java.io.*;
import java.util.*;
public class Frontend_try1 {
private static File fileOutput;
private static List<StringBuilder> eventTrans = new ArrayList<>();
public static void consoleInput(String[] namesArray, int[] ticketArray,File fileCurrentEvents){
System.out.println("Enter command:");
Scanner input = new Scanner(System.in);
String inputString = input.nextLine();
boolean correct = true;
do{
if(inputString.toUpperCase().equals( "LOGIN")) {
//enter login mode
login(namesArray, ticketArray,fileCurrentEvents);
correct = true;
}
if(inputString.toUpperCase().equals("LOGOUT")){
logout(namesArray, ticketArray,fileCurrentEvents);
correct=true;
}
if (!"LOGIN".toUpperCase().equals(inputString) || !"LOGOUT".toUpperCase().equals(inputString)){
System.out.println("Incorrect command, please enter command:");
input = new Scanner(System.in);
inputString = input.nextLine();
correct = false;
}
}while(!correct);
}
public static void login(String[] namesArray, int[] ticketArray,File fileCurrentEvents) {
System.out.println("Sales or Admin?");
Scanner input = new Scanner(System.in);
String inputString = input.nextLine();
boolean correct = true ;
do {
if(inputString.toUpperCase().equals("LOGOUT")){
logout(null, null, null);
}
else if(inputString.toUpperCase().equals("SALES")) {
//enter sales mode
sales(namesArray, ticketArray,fileCurrentEvents);
correct = true;
} else if (inputString.toUpperCase().equals("ADMIN")) {
//enter admin mode
admin(namesArray, ticketArray,fileCurrentEvents);
correct = true;
} else if (inputString.toUpperCase().equals("LOGOUT")) {
//enter logout mode
logout( namesArray, ticketArray, fileCurrentEvents);
correct = true;
} else {
//ask again
System.out.println("Invalid Input");
System.out.println("Sales or Admin?");
input = new Scanner(System.in);
inputString = input.nextLine();
correct = false;
}
}while(!correct);
}
public static void sales(String[] namesArray, int[] ticketArray,File fileCurrentEvents) {
//System.out.println("SALES");
System.out.println("Sales Mode");
System.out.println("Enter Command:");
Scanner input = new Scanner(System.in);
String inputString = input.nextLine();
boolean correct = true ;
do {
if(inputString.toUpperCase().equals("LOGOUT")){
logout( namesArray, ticketArray, fileCurrentEvents);
}
else if(inputString.toUpperCase().equals("SELL")) {
//enter sales Sell mode
salesSell(namesArray, ticketArray,fileCurrentEvents);
correct = true;
} else if (inputString.toUpperCase().equals("RETURN")) {
//enter sales Return mode
salesReturn(namesArray, ticketArray,fileCurrentEvents);
correct = true;
} else if (inputString.toUpperCase().equals("LOGOUT")) {
//enter Logout mode
logout( namesArray, ticketArray, fileCurrentEvents);
correct = true;
} else {
//ask again
System.out.println("Invalid Input");
System.out.println("Enter Command:");
input = new Scanner(System.in);
inputString = input.nextLine();
correct = false;
}
}while(!correct);
}
public static void salesSell(String[] namesArray, int[] ticketArray,File fileCurrentEvents) {
int index = 0;
String eventName = null;
int numberTickets = 0;
System.out.println("Sales Sell Mode");
System.out.println("What is the name of your event?");
Scanner input = new Scanner(System.in);
String inputString = input.nextLine();
if(inputString.toUpperCase().equals("LOGOUT")){
logout( namesArray, ticketArray, fileCurrentEvents);
}
try{
for(int i = 0; i < namesArray.length; i++) {
if(namesArray[i].equals(inputString)){
index = i;
}
}
eventName= namesArray[index];
numberTickets=ticketArray[index] ;
} catch (Exception e) {
System.out.println("Error: Event not found within file");
System.exit(1);
}
int event = inputString.length();
boolean charnumber = true;
do{
if(inputString.toUpperCase().equals("LOGOUT")){
logout( namesArray, ticketArray, fileCurrentEvents);
}
if(event< 0 || event >20){
System.out.println("No more than 20 characters allowed for name!");
System.out.println("Enter name:");
input = new Scanner(System.in);
inputString = input.nextLine();
event=inputString.length();
charnumber = false;
}
else{
charnumber = true;
}
} while(!charnumber);
System.out.println("How many tickets?");
input = new Scanner(System.in);
inputString = input.nextLine();
int digit;
while(true){
try {
digit = Integer.parseInt(inputString);
break;
}
catch(NumberFormatException e){
}
System.out.println("Please type a number!");
inputString = input.nextLine();
}
if( numberTickets - digit <0){
System.out.println("Illegal amount of tickets! Buy less ticket please.");
}
else{
int tickets = numberTickets - digit;
ticketArray[index]=tickets;
}
boolean dignumber = true;
do{
if(inputString.toUpperCase().equals("LOGOUT")){
logout( namesArray, ticketArray, fileCurrentEvents);
}
if(digit<0 || digit>8){
System.out.println("Only 8 tickets allowed to be sold!");
inputString = input.nextLine();
event=inputString.length();
dignumber = false;
digit= Integer.parseInt(inputString);
}
else{
dignumber= true;
}
}while(!dignumber);
}
public static boolean logout(String[] namesArray, int[] ticketArray,File fileCurrentEvents) {
FileWriter logoutFileWriter;
FileWriter currEventsFileWriter;
int numSpaces = 0;
try{
currEventsFileWriter = new FileWriter(fileCurrentEvents, true);
for(int i = 0; i < namesArray.length; i++ ) {
currEventsFileWriter.write(namesArray[i]);
numSpaces = 20 - (namesArray[i].length() + 4);
for(int j = 0; j < numSpaces; j++) {
currEventsFileWriter.write("_");
}
currEventsFileWriter.write(ticketArray[i]);
currEventsFileWriter.write(String.format("%n"));
}
} catch(IOException e) {
System.out.println("Rewriting Current Events File Error");
System.exit(1);
}
try {
logoutFileWriter = new FileWriter(fileOutput, true);
//Cycle through event trans file and write via filewriter
for(int i = 0; i < eventTrans.size(); i++ ) {
String transact = eventTrans.get(i).toString();
logoutFileWriter.write(transact);
logoutFileWriter.write(String.format("%n"));
}
// Signify end of file
logoutFileWriter.write("00 000000 00000");
logoutFileWriter.write(String.format("%n"));
logoutFileWriter.close();
fileOutput.createNewFile();
} catch(IOException e) {
System.out.println("Output File Error");
System.exit(1);
}
return true;
/*
for( int i = 0; i < 20; i++ ) {
System.out.println("");
}
System.out.println("Logged Out");
consoleInput();
*/
}
public static void main(String[] args){
try {
File fileCurrentEvents = new File(args[0]);
fileOutput = new File(args[1]);
// Read current events file for events & dates
FileReader fileRead = new FileReader(fileCurrentEvents);
BufferedReader buffRead = new BufferedReader(fileRead);
// Create strings for data in current events file
String currentLine;
String eventName;
Integer numberTickets;
List<Integer> numticket = new ArrayList<Integer>();
List<String> list = new ArrayList<String>();
int[] numarray= new int[numticket.size()];
String[] linesArray = list.toArray(new String[list.size()]);
// Cycle through current events file line by line
while((currentLine = buffRead.readLine()) != null) {
if (currentLine.equals("END_________________00000")){
break; // End of file
}
//Parse for event name & number of tickets
eventName = currentLine.substring(0, currentLine.lastIndexOf("_")).trim();
numberTickets = Integer.parseInt(currentLine.substring(currentLine.lastIndexOf
("_") + 1));
// Place event name and # tickets into data structure
// Add event name to event array list with same index as # tickets
// Parse int to get # tickets & add to arraylist for tickets with same index
while((eventName = buffRead.readLine()) != null){
list.add(eventName);
}
for (int i =0 ; i< list.size();i++){
linesArray[i]= list.get(i);
}
while((eventName = buffRead.readLine()) != null){
numticket.add(numberTickets);
}
for (int i =0 ; i< numticket.size();i++){
numarray[i]= numticket.get(i);
}
}
while(true) {
consoleInput(linesArray, numarray, fileCurrentEvents);
}
} catch (IOException e) {
System.out.println("File I/O Error"); //Print to console to signify error
e.printStackTrace();
System.exit(1);
}
}
}
如果您在这一行收到 ArrayOutOfBoundsIndexException
File fileCurrentEvents = new File(args[0]);
那么大概意思就是你用的array(args)index(0)是越界因为它大于数组的大小。
如果你的数组看起来像
[] //Zero entries
获取不到元素0（第一项），因为有none.
因此，当您 运行 代码时，您必须传入零参数。当你在命令行 运行 它时，在它后面添加文件名，或者在你的 IDE （Eclipse，IntelliJ，Sublime）中更改构建设置以将它添加到构建步骤中。
the error is being thrown on this line in the main method. File fileCurrentEvents = new File(args[0]);
那么你的 args 是空的（例如你的程序 运行 没有任何命令行参数，比如文件）。你可以添加一个默认值，比如
File fileCurrentEvents = new File(args.length > 0 ? args[0] : "default.txt");
在您的原始代码中，第 763 行实际上是：
for (int i = 0 ; i< list.size(); i++){
linesArray[i] = list.get(i); //<--------------THIS ONE!
}
当 linesArray 比 list 短时会导致 ArrayIndexOutOfBoundsException。发生这种情况是因为您之前通过
实例化了 linesArray
String[] linesArray = list.toArray(new String[list.size()]);
当 list 为空时，然后添加到 list 使其比您的数组长。
由于外部 while 循环似乎没有以任何其他方式使用 linesArray，您可能可以删除上面的 for 循环，并放置
linesArray = list.toArray(new String[list.size()]);
在第一个 while 循环之后创建包含所有元素的适当数组。
我在尝试使用 java 创建的票务系统时遇到问题。我正在尝试利用两个文件来读取和写入我的输入。我目前只使用 salesSell 方法进行测试。我正在使用终端传递参数。我遇到的问题是抛出的 arrayoutofbounds 异常。
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0 at cisc_327_frontend.Frontend_try1.main(Frontend_try1.java:763)
我传递的两个数组参数是从我当前事件文件中的同一行解析而来的。文件中一行的示例是："testevent1__________0003"。我似乎无法弄清楚我在哪里遇到这个问题。任何类型的指导将不胜感激。
package cisc_327_frontend;
import java.io.*;
import java.util.*;
public class Frontend_try1 {
private static File fileOutput;
private static List<StringBuilder> eventTrans = new ArrayList<>();
public static void consoleInput(String[] namesArray, int[] ticketArray,File fileCurrentEvents){
System.out.println("Enter command:");
Scanner input = new Scanner(System.in);
String inputString = input.nextLine();
boolean correct = true;
do{
if(inputString.toUpperCase().equals( "LOGIN")) {
//enter login mode
login(namesArray, ticketArray,fileCurrentEvents);
correct = true;
}
if(inputString.toUpperCase().equals("LOGOUT")){
logout(namesArray, ticketArray,fileCurrentEvents);
correct=true;
}
if (!"LOGIN".toUpperCase().equals(inputString) || !"LOGOUT".toUpperCase().equals(inputString)){
System.out.println("Incorrect command, please enter command:");
input = new Scanner(System.in);
inputString = input.nextLine();
correct = false;
}
}while(!correct);
}
public static void login(String[] namesArray, int[] ticketArray,File fileCurrentEvents) {
System.out.println("Sales or Admin?");
Scanner input = new Scanner(System.in);
String inputString = input.nextLine();
boolean correct = true ;
do {
if(inputString.toUpperCase().equals("LOGOUT")){
logout(null, null, null);
}
else if(inputString.toUpperCase().equals("SALES")) {
//enter sales mode
sales(namesArray, ticketArray,fileCurrentEvents);
correct = true;
} else if (inputString.toUpperCase().equals("ADMIN")) {
//enter admin mode
admin(namesArray, ticketArray,fileCurrentEvents);
correct = true;
} else if (inputString.toUpperCase().equals("LOGOUT")) {
//enter logout mode
logout( namesArray, ticketArray, fileCurrentEvents);
correct = true;
} else {
//ask again
System.out.println("Invalid Input");
System.out.println("Sales or Admin?");
input = new Scanner(System.in);
inputString = input.nextLine();
correct = false;
}
}while(!correct);
}
public static void sales(String[] namesArray, int[] ticketArray,File fileCurrentEvents) {
//System.out.println("SALES");
System.out.println("Sales Mode");
System.out.println("Enter Command:");
Scanner input = new Scanner(System.in);
String inputString = input.nextLine();
boolean correct = true ;
do {
if(inputString.toUpperCase().equals("LOGOUT")){
logout( namesArray, ticketArray, fileCurrentEvents);
}
else if(inputString.toUpperCase().equals("SELL")) {
//enter sales Sell mode
salesSell(namesArray, ticketArray,fileCurrentEvents);
correct = true;
} else if (inputString.toUpperCase().equals("RETURN")) {
//enter sales Return mode
salesReturn(namesArray, ticketArray,fileCurrentEvents);
correct = true;
} else if (inputString.toUpperCase().equals("LOGOUT")) {
//enter Logout mode
logout( namesArray, ticketArray, fileCurrentEvents);
correct = true;
} else {
//ask again
System.out.println("Invalid Input");
System.out.println("Enter Command:");
input = new Scanner(System.in);
inputString = input.nextLine();
correct = false;
}
}while(!correct);
}
public static void salesSell(String[] namesArray, int[] ticketArray,File fileCurrentEvents) {
int index = 0;
String eventName = null;
int numberTickets = 0;
System.out.println("Sales Sell Mode");
System.out.println("What is the name of your event?");
Scanner input = new Scanner(System.in);
String inputString = input.nextLine();
if(inputString.toUpperCase().equals("LOGOUT")){
logout( namesArray, ticketArray, fileCurrentEvents);
}
try{
for(int i = 0; i < namesArray.length; i++) {
if(namesArray[i].equals(inputString)){
index = i;
}
}
eventName= namesArray[index];
numberTickets=ticketArray[index] ;
} catch (Exception e) {
System.out.println("Error: Event not found within file");
System.exit(1);
}
int event = inputString.length();
boolean charnumber = true;
do{
if(inputString.toUpperCase().equals("LOGOUT")){
logout( namesArray, ticketArray, fileCurrentEvents);
}
if(event< 0 || event >20){
System.out.println("No more than 20 characters allowed for name!");
System.out.println("Enter name:");
input = new Scanner(System.in);
inputString = input.nextLine();
event=inputString.length();
charnumber = false;
}
else{
charnumber = true;
}
} while(!charnumber);
System.out.println("How many tickets?");
input = new Scanner(System.in);
inputString = input.nextLine();
int digit;
while(true){
try {
digit = Integer.parseInt(inputString);
break;
}
catch(NumberFormatException e){
}
System.out.println("Please type a number!");
inputString = input.nextLine();
}
if( numberTickets - digit <0){
System.out.println("Illegal amount of tickets! Buy less ticket please.");
}
else{
int tickets = numberTickets - digit;
ticketArray[index]=tickets;
}
boolean dignumber = true;
do{
if(inputString.toUpperCase().equals("LOGOUT")){
logout( namesArray, ticketArray, fileCurrentEvents);
}
if(digit<0 || digit>8){
System.out.println("Only 8 tickets allowed to be sold!");
inputString = input.nextLine();
event=inputString.length();
dignumber = false;
digit= Integer.parseInt(inputString);
}
else{
dignumber= true;
}
}while(!dignumber);
}
public static boolean logout(String[] namesArray, int[] ticketArray,File fileCurrentEvents) {
FileWriter logoutFileWriter;
FileWriter currEventsFileWriter;
int numSpaces = 0;
try{
currEventsFileWriter = new FileWriter(fileCurrentEvents, true);
for(int i = 0; i < namesArray.length; i++ ) {
currEventsFileWriter.write(namesArray[i]);
numSpaces = 20 - (namesArray[i].length() + 4);
for(int j = 0; j < numSpaces; j++) {
currEventsFileWriter.write("_");
}
currEventsFileWriter.write(ticketArray[i]);
currEventsFileWriter.write(String.format("%n"));
}
} catch(IOException e) {
System.out.println("Rewriting Current Events File Error");
System.exit(1);
}
try {
logoutFileWriter = new FileWriter(fileOutput, true);
//Cycle through event trans file and write via filewriter
for(int i = 0; i < eventTrans.size(); i++ ) {
String transact = eventTrans.get(i).toString();
logoutFileWriter.write(transact);
logoutFileWriter.write(String.format("%n"));
}
// Signify end of file
logoutFileWriter.write("00 000000 00000");
logoutFileWriter.write(String.format("%n"));
logoutFileWriter.close();
fileOutput.createNewFile();
} catch(IOException e) {
System.out.println("Output File Error");
System.exit(1);
}
return true;
/*
for( int i = 0; i < 20; i++ ) {
System.out.println("");
}
System.out.println("Logged Out");
consoleInput();
*/
}
public static void main(String[] args){
try {
File fileCurrentEvents = new File(args[0]);
fileOutput = new File(args[1]);
// Read current events file for events & dates
FileReader fileRead = new FileReader(fileCurrentEvents);
BufferedReader buffRead = new BufferedReader(fileRead);
// Create strings for data in current events file
String currentLine;
String eventName;
Integer numberTickets;
List<Integer> numticket = new ArrayList<Integer>();
List<String> list = new ArrayList<String>();
int[] numarray= new int[numticket.size()];
String[] linesArray = list.toArray(new String[list.size()]);
// Cycle through current events file line by line
while((currentLine = buffRead.readLine()) != null) {
if (currentLine.equals("END_________________00000")){
break; // End of file
}
//Parse for event name & number of tickets
eventName = currentLine.substring(0, currentLine.lastIndexOf("_")).trim();
numberTickets = Integer.parseInt(currentLine.substring(currentLine.lastIndexOf
("_") + 1));
// Place event name and # tickets into data structure
// Add event name to event array list with same index as # tickets
// Parse int to get # tickets & add to arraylist for tickets with same index
while((eventName = buffRead.readLine()) != null){
list.add(eventName);
}
for (int i =0 ; i< list.size();i++){
linesArray[i]= list.get(i);
}
while((eventName = buffRead.readLine()) != null){
numticket.add(numberTickets);
}
for (int i =0 ; i< numticket.size();i++){
numarray[i]= numticket.get(i);
}
}
while(true) {
consoleInput(linesArray, numarray, fileCurrentEvents);
}
} catch (IOException e) {
System.out.println("File I/O Error"); //Print to console to signify error
e.printStackTrace();
System.exit(1);
}
}
}
如果您在这一行收到 ArrayOutOfBoundsIndexException
File fileCurrentEvents = new File(args[0]);
那么大概意思就是你用的array(args)index(0)是越界因为它大于数组的大小。
如果你的数组看起来像
[] //Zero entries
获取不到元素0（第一项），因为有none.
因此，当您 运行 代码时，您必须传入零参数。当你在命令行 运行 它时，在它后面添加文件名，或者在你的 IDE （Eclipse，IntelliJ，Sublime）中更改构建设置以将它添加到构建步骤中。
the error is being thrown on this line in the main method.
File fileCurrentEvents = new File(args[0]);
那么你的 args 是空的（例如你的程序 运行 没有任何命令行参数，比如文件）。你可以添加一个默认值，比如
File fileCurrentEvents = new File(args.length > 0 ? args[0] : "default.txt");
在您的原始代码中，第 763 行实际上是：
for (int i = 0 ; i< list.size(); i++){
linesArray[i] = list.get(i); //<--------------THIS ONE!
}
当 linesArray 比 list 短时会导致 ArrayIndexOutOfBoundsException。发生这种情况是因为您之前通过
linesArray
String[] linesArray = list.toArray(new String[list.size()]);
当 list 为空时，然后添加到 list 使其比您的数组长。
由于外部 while 循环似乎没有以任何其他方式使用 linesArray，您可能可以删除上面的 for 循环，并放置
linesArray = list.toArray(new String[list.size()]);
在第一个 while 循环之后创建包含所有元素的适当数组。