爲什麼在運行這個程序時會出現這個java.lang.StringIndexOutOfBoundsException錯誤？

-1

String fullWord; 
    String firstWord; 
    String secondWord; 
    String thirdWord; 
    String fourthWord; 

    int firstPositionOfAsterisk; 
    int secondPositionOfAsterisk; 
    int thirdPositionOfAsterisk; 
    int fullWordCharacters; 
    int firstWordCharacters; 
    int secondWordCharacters; 
    int thirdWordCharacters; 
    int fourthWordCharacters; 

    char lastLetterFirstWord; 


    // I will prompt the user to enter four words seperated by a * 
    fullWord = JOptionPane.showInputDialog("Please enter four words: "); 

    // I will use the position of the * to make things easier 
    firstPositionOfAsterisk = fullWord.indexOf("*"); 

    firstWord = fullWord.substring(0, firstPositionOfAsterisk); 

    secondPositionOfAsterisk = firstWord.indexOf("*"); 

    secondWord = fullWord.substring(firstPositionOfAsterisk + 1, secondPositionOfAsterisk); 

    thirdPositionOfAsterisk = secondWord.indexOf("*"); 

    thirdWord = fullWord.substring(secondPositionOfAsterisk + 1, thirdPositionOfAsterisk); 

    fourthWord = fullWord.substring(thirdPositionOfAsterisk + 1); 

    firstWordCharacters = firstWord.length(); 
    System.out.println(firstWord +" has a length of " + firstWordCharacters + " characters"); 


    secondWordCharacters = secondWord.length(); 
    System.out.println(secondWord +" has length of " + secondWordCharacters + " characters"); 

    thirdWordCharacters = thirdWord.length(); 
    System.out.println(thirdWord +" has length of " + thirdWordCharacters + " characters"); 

    fourthWordCharacters = fourthWord.length(); 
    System.out.println(fourthWord +" has length of " + fourthWordCharacters + " characters"); 

    lastLetterFirstWord = firstWord.charAt(firstPositionOfAsterisk - 1); 
    System.out.println("The last letter of " + firstWord + "is " + lastLetterFirstWord); 

    fullWord = firstWord + secondWord + thirdWord + fourthWord; 

    fullWordCharacters = fullWord.length(); 
    System.out.println(firstWord +", " + secondWord + ", " + thirdWord + ", " + fourthWord + "has length of" + fullWordCharacters);

我試圖讓用戶輸入4個字分隔由「*」，例如她會* * *電話回來，我想輸出喜歡這樣爲什麼在運行這個程序時會出現這個java.lang.StringIndexOutOfBoundsException錯誤？

她有長3 會具有長度爲4 呼叫具有長度4 背面具有長度4

中的*符號的位置處發現的：3，圖8和13

的最後一個字符的她爲s

她，將，呼叫，回來的長度是15

但我不斷收到此java.lang.StringIndexOutOfBoundsException錯誤。我該如何解決？

這條線崩潰程序

secondWord = fullWord.substring（firstPositionOfAsterisk + 1，secondPositionOfAsterisk）;

來源

2013-02-24 user2097612

簡單..閱讀.. String.substring(int, int)

而且你會看到

throws 
    IndexOutOfBoundsException - if the beginIndex is negative, or endIndex is larger than the length of this String object, or beginIndex is larger than endIndex.

的重要組成部分，是或beginIndex大於endIndex的大

可能是你secondPositionOfAsterisk得到負值（-1）值

來源

2013-02-24 00:36:26 thiagoh

firstWord = fullWord.substring(0, firstPositionOfAsterisk);

上面將字符串的第一部分取爲第一個星號，因此它不包含星號。因此，這將返回-1：

secondPositionOfAsterisk = firstWord.indexOf("*");

那麼這將失敗（因爲-1是不是一個有效的索引）

secondWord = fullWord.substring(firstPositionOfAsterisk + 1, secondPositionOfAsterisk);

我想這：

secondPositionOfAsterisk = firstWord.indexOf("*");

應該

int offset = firstWord.length()+1; 
secondPositionOfAsterisk = firstWord.indexOf("*", offset);

或類似的東西。

我個人認爲String#split是一種更好的選擇。

來源

2013-02-24 00:40:42 Dukeling

爲什麼在運行這個程序時會出現這個java.lang.StringIndexOutOfBoundsException錯誤？

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