![](/img/trans.png)
[英]StringIndexOutOfBoundsException in my MapReduce code
[英]What is the cause of an StringIndexOutOfBoundsException in my code
在我的學校作業中,我必須制作遞歸方法,並且只能使用.charAt,.indexOf,.substring,.toLowerCase,.concat和我在代碼中使用的其他一些方法。
這是代碼
/*
* Lab to perform different functions on Strings
* all methods are static
* only two methods should be public
* all other methods are internal (only used in the class)
*/
package stringutil;
/**
* @author [REDACTED]
*/
public class StringUtil {
public static boolean inOut(String input){//the argument is in main
int len = input.length();
boolean test;
input = input.toLowerCase();
//call the cleaners
input = StringUtil.cleanse(input, len);
//this is le final product
String reverse = StringUtil.flip(input);
test = input.equals(reverse);
return test;
}
private static String cleanse(String raw, int count){
if (count < 0)
return ("");
//this means that there was invalid punctuation
else{
char ch;
ch = raw.charAt(count);
if (ch >= 97 && ch <= 122 || ch >= 48 && ch<= 57){
//call method again with count-1 | string is same
return cleanse(raw, count-1);
}
else{ //character ain't ok yo
if (raw.indexOf(count) == -1){
raw = raw.substring(raw.length()-count, count-1);
}
else
raw = raw.substring(0,count-1).concat(raw.substring(count+1));
return cleanse(raw, count);
}
}
}
public static String flip(String input){
String newer;
// base case
if (input.length() == 1){
return input;
}
else{
//take the last letter and make it the new start
newer = input.substring(input.length()-1);
input = input.substring(0, input.length()-1);
return newer + flip(input);
}
//input = newer +
// flip(input.substring(0, input.length()-1));
}
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
// TODO code application logic here
System.out.println(StringUtil.flip("aashf"));
System.out.println(StringUtil.inOut("what, t;haw"));
}
}
所以我在跑步后得到這個
fhsaa
Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 11
at java.lang.String.charAt(String.java:646)
at stringutil.StringUtil.cleanse(StringUtil.java:36)
at stringutil.StringUtil.inOut(StringUtil.java:21)
at stringutil.StringUtil.main(StringUtil.java:78)
Java Result: 1
BUILD SUCCESSFUL (total time: 0 seconds)
我已經擺弄了清理不是字母或數字的字符的方法,但系統似乎喜歡從字符串到字符的轉移。
我的翻轉方法有效,但我的清理總是遇到一個超出范圍的錯誤。 我嘗試添加許多東西以確保它在范圍內,但這只會增加問題。
是的。字符串的.length()
返回字符串中的一個或多個字符,因此你總是檢查越界,因為你需要在得到長度之后做減去一個,以便不超出范圍因為.charAt()
返回特定地點的信
有幾個邏輯錯誤; 我想這就是你想要做的:
/*
* Lab to perform different functions on Strings
* all methods are static
* only two methods should be public
* all other methods are internal (only used in the class)
*/
package stringutil;
/**
* @author [REDACTED]
*/
public class StringUtil {
public static boolean inOut(String input) {// the argument is in main
int len = input.length();
boolean test;
input = input.toLowerCase();
// call the cleaners
input = StringUtil.cleanse(input, len - 1);
// this is le final product
String reverse = StringUtil.flip(input);
test = input.equals(reverse);
return test;
}
private static String cleanse(String raw, int count) {
if (count < 0)
return raw;
// this means that there was invalid punctuation
else {
char ch;
ch = raw.charAt(count);
if (ch >= 97 && ch <= 122 || ch >= 48 && ch <= 57) {
// call method again with count-1 | string is same
return cleanse(raw, count - 1);
} else { // character ain't ok yo
raw = raw.substring(0, count).concat(raw.substring(count + 1));
return cleanse(raw, count - 2);
}
}
}
public static String flip(String input) {
String newer;
// base case
if (input.length() == 1) {
return input;
} else {
// take the last letter and make it the new start
newer = input.substring(input.length() - 1);
input = input.substring(0, input.length() - 1);
return newer + flip(input);
}
// input = newer +
// flip(input.substring(0, input.length()-1));
}
/**
*
* @param args
* the command line arguments
*
*/
public static void main(String[] args) {
// TODO code application logic here
System.out.println(StringUtil.flip("aashf"));
System.out.println(StringUtil.inOut("what, t;ahw"));
}
}
基本上,你的// character ain't ok yo
代碼段是有缺陷的,你的cleanse
呼叫也是如此。 我還沒有檢查出你的其余代碼,但是main
調用的代碼部分似乎現在正在運行。 此外,作為前TA,請考慮在您的代碼中添加注釋。
PS:我還將輸入字符串更改為輸出true以調用inOut
。
如果檢查,問題是使用此else代碼塊
raw = raw.substring(0,count-1).concat(raw.substring(count+1));
您正在嘗試使用子字符串連接一個位置,該位置超出范圍。 count是String的長度,並且您嘗試使用count + 1位置創建子字符串。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.