Java IndexOutOfBoundsException添加长数字时出错
我正在尝试编写一个java应用程序,它使用LinkedList将5个长数字相加。在跑步结束时,我得到以下信息: 主线程java.lang.IndexOutOfBoundsException中的异常:索引: 0,大小:0 在java.util.LinkedList.checkElementIndexLinkedList.java:555在java.util.LinkedList.removeLinkedList.java:525在 Assignment1.LongNumbers.removeLongNumbers.java:33 at Assignment1.LongNumbers.mainLongNumbers.java:92 代码如下:Java IndexOutOfBoundsException添加长数字时出错,java,linked-list,indexoutofboundsexception,Java,Linked List,Indexoutofboundsexception,我正在尝试编写一个java应用程序,它使用LinkedList将5个长数字相加。在跑步结束时,我得到以下信息: 主线程java.lang.IndexOutOfBoundsException中的异常:索引: 0,大小:0 在java.util.LinkedList.checkElementIndexLinkedList.java:555在java.util.LinkedList.removeLinkedList.java:525在 Assignment1.LongNumbers.removeLon
import java.util.*;
/**
*
* @author .....
*/
public class LongNumbers
{
private List<Integer> [] theLists;
public LongNumbers() {
this.theLists = new LinkedList[6];
for (int i=0; i<6; i++)
this.theLists[i]= new LinkedList<>();
}
public void add(int location, int digit) {
//add digit at head of LinkedList given by location
theLists[location].add(digit);
}
public int remove(int location) {
//remove a digit from LinkedList given by location
return theLists[location].remove(location); //LongNumbers.java:33
}
public boolean isEmpty(int location) {
//check for an empty LinkedList given by location
return theLists[location].isEmpty();
}
public static void main(String[] args) {
Scanner stdIn = new Scanner(System.in);
//Local Variables
int digit;
int carry = 0;
int numberAt = 0;
int largestNumLength = 0;
char[] digits;
String number;
boolean userWantstoQuit = false;
LongNumbers Lists = new LongNumbers();
System.out.println("The program will enter up to 5 numbers and add them up.");
System.out.println();
while(!userWantstoQuit && numberAt != 5){
System.out.print("Enter a number, enter -1 to quit entry phase: ");
number = stdIn.nextLine();
if((number.compareTo("-1")) == 0)
userWantstoQuit = true;
else{
digits = new char[number.length()];
for(int i=0;i<number.length();i++)
digits[i] = number.charAt(i);
for(int i=0;i<number.length();i++){
int tempValue = digits[i] - 48;
try{
Lists.add(numberAt, tempValue);
}
catch(NumberFormatException nfe){
System.out.println("Invalid Input. Please try again.");
break;
}
if(i == (number.length() - 1))
numberAt++;
if(number.length() > largestNumLength)
largestNumLength = number.length();
}
}
}
for(int j=0;j<largestNumLength;j++){
int tempDigit = 0;
int index = 0;
while(index < numberAt){
if(Lists.theLists[index].get(0) != null){
tempDigit += Lists.theLists[index].get(0);
Lists.remove(0); //LongNumbers.java:99
}
index++;
}
digit = carry + tempDigit;
if(j < numberAt){
carry = digit/10;
digit = digit%10;
}
Lists.add(5, digit);
}
System.out.print("The sum of the numbers is: ");
for(int i=0;i<Lists.theLists[5].size();i++){
System.out.print(Lists.theLists[5].get(i));
}
System.out.println();
System.out.println();
System.out.println();
}//end main
}//end class
首先,我不认为你可以有一个列表对象数组 您还应该确保列表已初始化,并且在给定位置有一个项目 因此,您的方法可能如下所示:
public int remove(int location)
{
if(theLists != null)
if(theLists.size() > location)
return theLists.remove(location);
return 0;
}
public int remove(int location, int index) {
//remove a digit from LinkedList given by location
return theLists[index].remove(location); //LongNumbers.java:33
}
如果需要列表的两个维度,可以尝试使用列表
将所有E都视为整数。请查看此处的代码:
while(index < numberAt){
if(Lists.theLists[index].get(0) != null){
tempDigit += Lists.theLists[index].get(0);
Lists.remove(0); //LongNumbers.java:99
}
index++;
}
在我描述的场景中,位置是0。但您的第0个列表已为空
编辑:重写删除方法,如下所示:
public int remove(int location)
{
if(theLists != null)
if(theLists.size() > location)
return theLists.remove(location);
return 0;
}
public int remove(int location, int index) {
//remove a digit from LinkedList given by location
return theLists[index].remove(location); //LongNumbers.java:33
}
无论何时调用此方法,都要传递要使用的列表的索引。例如:
while(index < numberAt){
if(Lists.theLists[index].get(0) != null){
tempDigit += Lists.theLists[index].get(0);
Lists.remove(0, index); //LongNumbers.java:99
}
index++;
}
最后:在将来,请结构化您的代码,在这种非结构化的状态下阅读它是一件非常痛苦的事情,阅读如何编写代码。如果您能在代码中指出行的长度,那就太好了。java:33抱歉了。编辑已完成。堆栈跟踪非常清楚地告诉您,在remove方法中,您请求的是一个大小为零的列表的索引0处的元素,即一个空列表。看看你是如何初始化列表的。