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Java lang arrayindexoutofboundsexception

Solving java.lang.ArrayindexOutOfBoundsException: 1 in Java

The error ArrayIndexOutOfBoundsException : 1 means index 1 is inval >ArrayIndexOutfBoundsException comes when your code, mostly for loop tries to access an inval >IndexOutOfBoundsException which is used to throw error related to invalid index e.g. try to access outside of length in String etc.

An array is a data structure which is the base for many advanced data structure e.g. list, hash table or a binary tree. The array stores elements in the contiguous memory location and it can also have multiple dimension e.g. a two-dimensional array. You can use the 2D array to represent matrix, a board in games like Tetris, Chess and other board games.

A good knowledge of data structure and the algorithm is a must for any good programmer. You should read a good introductory book e.g. Introduction to Algorithms by Thomas Cormen to learn more about array in Java.

Understanding ArrayIndexOutOfBoundsException

This error comes when you are accessing or iterating over array directly or indirectly. Directly means you are dealing with array type e.g. String[] or main method, or an integer[] you have created in your program. Indirectly means via Collection classes which internally use an array e.g. ArrayList or HashMap.

Now let’s understand what information the associated error message gives us:
java.lang.ArrayIndexOutOfBoundsException: 0 means you are trying to access index 0 which is invalid, which in turn means the array is empty.

Here is a Java program which reproduces this error by accessing the first element of the empty array i.e. array with zero length:

You can see the accessing first element of an empty array resulted in the ArrayIndexOutOfBoundsException in Java.

java.lang.ArrayindexOutOfBoundsException: 1 means index 1 is invalid, which in turn means array contains just one element. Here is a Java program which will throw this error:

Similarly, java.lang.ArrayIndexOutOfBoundsException: 2 means index 2 is invalid, which means array has just 2 elements and you are trying to access the third element of the array.

Sometimes when a programmer makes switch from C/C++ to Java they forget that Java does the bound checking at runtime, which is a major difference between C++ and Java Array. You should read Core Java Volume 1 By Cay S. Horstmann if you are learning Java and knows C++. The author often highlights the key difference between C++ and Java while teaching important concepts.

Here is nice slide of some good tips to avoid ArrayIndexOutOfBondsException in Java:

How to avoid ArrayIndexOutOfBoundsException in Java

In order to avoid the java.lang.ArrayIndexOutOfBoundsException, you should always do the bound check before accessing array element e.g.

Always remember that array index starts at 0 and not 1 and an empty array has no element in it. So accessing the first element will give you the java.lang.ArrayIndexOutOfBoundsException : 0 error in Java.

You should always pay to one-off errors while looping over an array in Java. The programmer often makes mistakes which result in either missing first or last element of the array by messing 1st element or finishing just before the last element by incorrectly using the , >= or operator in for loops. For example, following program will never print the last element of the array. The worst part is there won’t be any compile time error or runtime exception. It’s pure logical error which will cause incorrect calculation.

You can see the first element of array i.e. 2 is never get printed. There is no compile time or runtime error, though.

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Here are few handy tips to avoid ArrayIndexOutOfBoundsException in Java:

  1. Always remember that array is zero based index, first element is at 0th index and last element is at length — 1 index.
  2. Pay special attention to start and end condition of loop.
  3. Beware of one-off errors like above.

Solving java.lang.ArrayindexOutOfBoundsException: 1 in Java

The error ArrayIndexOutOfBoundsException : 1 means index 1 is inval >ArrayIndexOutfBoundsException comes when your code, mostly for loop tries to access an inval >IndexOutOfBoundsException which is used to throw error related to invalid index e.g. try to access outside of length in String etc.

An array is a data structure which is the base for many advanced data structure e.g. list, hash table or a binary tree. The array stores elements in the contiguous memory location and it can also have multiple dimension e.g. a two-dimensional array. You can use the 2D array to represent matrix, a board in games like Tetris, Chess and other board games.

A good knowledge of data structure and the algorithm is a must for any good programmer. You should read a good introductory book e.g. Introduction to Algorithms by Thomas Cormen to learn more about array in Java.

Understanding ArrayIndexOutOfBoundsException

This error comes when you are accessing or iterating over array directly or indirectly. Directly means you are dealing with array type e.g. String[] or main method, or an integer[] you have created in your program. Indirectly means via Collection classes which internally use an array e.g. ArrayList or HashMap.

Now let’s understand what information the associated error message gives us:
java.lang.ArrayIndexOutOfBoundsException: 0 means you are trying to access index 0 which is invalid, which in turn means the array is empty.

Here is a Java program which reproduces this error by accessing the first element of the empty array i.e. array with zero length:

You can see the accessing first element of an empty array resulted in the ArrayIndexOutOfBoundsException in Java.

java.lang.ArrayindexOutOfBoundsException: 1 means index 1 is invalid, which in turn means array contains just one element. Here is a Java program which will throw this error:

Similarly, java.lang.ArrayIndexOutOfBoundsException: 2 means index 2 is invalid, which means array has just 2 elements and you are trying to access the third element of the array.

Sometimes when a programmer makes switch from C/C++ to Java they forget that Java does the bound checking at runtime, which is a major difference between C++ and Java Array. You should read Core Java Volume 1 By Cay S. Horstmann if you are learning Java and knows C++. The author often highlights the key difference between C++ and Java while teaching important concepts.

Here is nice slide of some good tips to avoid ArrayIndexOutOfBondsException in Java:

How to avoid ArrayIndexOutOfBoundsException in Java

In order to avoid the java.lang.ArrayIndexOutOfBoundsException, you should always do the bound check before accessing array element e.g.

Always remember that array index starts at 0 and not 1 and an empty array has no element in it. So accessing the first element will give you the java.lang.ArrayIndexOutOfBoundsException : 0 error in Java.

You should always pay to one-off errors while looping over an array in Java. The programmer often makes mistakes which result in either missing first or last element of the array by messing 1st element or finishing just before the last element by incorrectly using the , >= or operator in for loops. For example, following program will never print the last element of the array. The worst part is there won’t be any compile time error or runtime exception. It’s pure logical error which will cause incorrect calculation.

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You can see the first element of array i.e. 2 is never get printed. There is no compile time or runtime error, though.

Here are few handy tips to avoid ArrayIndexOutOfBoundsException in Java:

  1. Always remember that array is zero based index, first element is at 0th index and last element is at length — 1 index.
  2. Pay special attention to start and end condition of loop.
  3. Beware of one-off errors like above.

Понимание Array IndexOutofbounds Исключение в Java

Java поддерживает создание и манипулирование массивами , как структуру данных. Индекс массива — это целочисленное значение, значение которого находится в интервале [0, n-1], где n — размер массива. Если сделан запрос на отрицательный или индекс, который больше или равен размеру массива, то JAVA выдает исключение ArrayIndexOutOfBounds. Это не похоже на C / C ++, где не выполняется проверка индекса привязки.

ArrayIndexOutOfBoundsException — исключение времени выполнения, выдаваемое только во время выполнения. Компилятор Java не проверяет эту ошибку во время компиляции программы.

// Индекс общей причины выходит за пределы

public class NewClass2

public static void main(String[] args)

for ( int i= 0 ; i

Ошибка выполнения выдает исключение:

Выход:

Здесь, если вы внимательно посмотрите, массив имеет размер 5. Следовательно, при доступе к его элементу с помощью цикла for максимальное значение индекса может быть 4, но в нашей программе оно увеличивается до 5 и, следовательно, является исключением.

Давайте посмотрим еще один пример использования arraylist:

// Еще один пример с индексом вне границ

public class NewClass2

public static void main(String[] args)

ArrayList lis = new ArrayList<>();

Ошибка выполнения здесь немного более информативна, чем предыдущая

Давайте поймем это немного подробнее

  • Индекс здесь определяет индекс, к которому мы пытаемся получить доступ.
  • Размер дает нам информацию о размере списка.
  • Поскольку размер равен 2, последний индекс, к которому мы можем получить доступ (2-1) = 1, и, следовательно, исключение

Правильный способ доступа к массиву:

Обработка исключения:

  • Использовать цикл for-each : он автоматически обрабатывает индексы при доступе к элементам массива. Пример-
  • Используйте Try-Catch: рассмотрите возможность включения вашего кода в оператор try-catch и соответственно обработайте исключение. Как уже упоминалось, Java не позволит вам получить доступ к недопустимому индексу и обязательно выдаст исключение ArrayIndexOutOfBoundsException. Однако мы должны быть осторожны внутри блока оператора catch, потому что, если мы не обработаем исключение надлежащим образом, мы можем скрыть его и, таким образом, создать ошибку в вашем приложении.

Эта статья предоставлена Rishabh Mahrsee . Если вам нравится GeeksforGeeks и вы хотите внести свой вклад, вы также можете написать статью и отправить ее по почте на contrib@geeksforgeeks.org. Смотрите свою статью, появляющуюся на главной странице GeeksforGeeks, и помогите другим вундеркиндам.

Пожалуйста, напишите комментарии, если вы обнаружите что-то неправильное, или вы хотите поделиться дополнительной информацией по обсуждаемой теме

Java Exception Handling – java.lang.ArrayIndexOutOfBoundsException

Today we’ll take another journey through the “Land of Errors” of our ongoing Java Exception Handling series, with a deep dive into the java.lang.ArrayIndexOutOfBoundsException. As the name clearly indicates, the ArrayIndexOutOfBoundsException is thrown when an index is passed to an array which doesn’t contain an element at that particular index location.

In this article we’ll look a bit closer at the java.lang.ArrayIndexOutOfBoundsException by examining where it sits in the Java Exception Hierarchy. We’ll also go over a few simple, functional code samples illustrating how ArrayIndexOutOfBoundsExceptions are commonly thrown, so let’s get crackin’!

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The Technical Rundown

  • All Java errors implement the java.lang.Throwable interface, or are extended from another inherited class therein.
  • java.lang.Exception inherits from java.lang.Throwable .
  • java.lang.RuntimeException inherits from java.lang.Exception .
  • java.lang.IndexOutOfBoundsException inherits from java.lang.RuntimeException .
  • Lastly, java.lang.ArrayIndexOutOfBoundsException inherits from java.lang.IndexOutOfBoundsException .

When Should You Use It?

Since Java has internal classes and object structures to manage Arrays — and because said objects will produce errors like the java.lang.ArrayIndexOutOfBoundsException on their own — there will rarely be a situation where you’ll need to explicitly throw your own ArrayIndexOutOfBoundsException. For example, if you were creating your own data structure object that contained a non-array collection of elements, you’d likely want to explicitly throw a java.lang.IndexOutOfBoundsException , as opposed to a java.lang.ArrayIndexOutOfBoundsException , since the JVM will handle that for you most of the time.

That said, to see how ArrayIndexOutOfBoundsExceptions are commonly thrown we’ll start with the full working code sample, after which we’ll explore it in more detail:

To illustrate a common problem when using arrays we have two similar methods, iterateArray(Book[] list) and iterateArrayInvalid(Book[] list) :

These methods don’t do anything fancy and, in fact, basically only serve as wrappers to stick our try-catch blocks in, and to differentiate the slight differences in loop logic between the two. Specifically, as indicated by the code comments, the iterateArrayInvalid(Book[] list) method contains a termination expression that allows index to be less than or equal to the length of list . Since, like most languages, Java uses zero-based numbering to index Arrays and other collections, an index equal to the length of an array will be one greater than the largest index. To better illustrate, consider this table of Arrays showing each array’s length and its maximum index :

Length/CountMaximum Index
1
21
32
43
54
etc.etc.

With that in mind, we’ll get started testing both of the iteration methods. We’ll use our Book class just to keep things a little more interesting by creating a few elements for our array, then pass it to both methods so we can review the output of each:

The output from iterateArray(Book[] list) is just as expected, outputting all four elements before execution is completed:

On the other hand, invoking iterateArrayInvalid(Book[] list) runs into a problem. While we successfully output all four elements, as mentioned above, the for loop iterates one too many times, resulting in a call to list[4] , which is an unknown index. This throws a java.lang.ArrayIndexOutOfBoundsException , indicating the index value that was out of bounds:

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