Array out of bounds in Java - how to solve java.lang.ArrayIndexOutOfBoundsException?

Java is a widely used programming language, and arrays are a very common data structure in the Java language. When using an array, you may sometimes encounter the "java.lang.ArrayIndexOutOfBoundsException" exception, which is caused by the array subscript going out of bounds. So how to solve this exception?

1. Introduction to exceptions

"java.lang.ArrayIndexOutOfBoundsException" is an exception provided by the Java platform, which will be thrown when the program is running. This exception indicates that the array subscript is out of bounds, that is, a non-existent array element is accessed. The error message usually tells us the location (number of rows) where the exception occurred and the cause of the exception, for example:

java. lang.ArrayIndexOutOfBoundsException: 5

The exception information tells us that at the 5th position of the program, an element beyond the bounds of the array was accessed, causing the program to throw this exception.

2. Analysis of the cause of the exception

When we use an array, we often need to access the elements in the array through subscripts. Array subscripts in Java start from 0 and continue until the length of the array is reduced by 1. For example, for an array of length 5, its subscript range is 0~4.

When we try to use the length of the array as a subscript, an out-of-bounds exception will occur. For example:

int[] array = new int[5];
int a = array[5]; // An out-of-bounds exception will occur here

In the second line of code, we Trying to access the 6th element in an array of length 5. Since array subscripts start at 0, the maximum subscript for an array of size 5 is 4, not 5. Therefore, the program will throw ArrayIndexOutOfBoundsException exception.

Similarly, when using a for loop to access array elements in sequence, if the subscript of the loop exceeds the range of the array, an out-of-bounds exception will also occur. For example:

int[] array = new int[5];
for(int i=0; i<=5; i ){ //The value of i here takes the maximum value of the array subscript Add 1

System.out.println(array[i]); // 这里会产生越界异常

}

The i value in the second line of code starts from 0 and is increased by 1 successively. The number of loops is 6. Since the maximum value of the array subscript is 4, the value of i will be 5 in the 6th loop, which exceeds the array subscript range. Therefore, the program will also throw ArrayIndexOutOfBoundsException exception.

3. Abnormal solution

1. By mastering the array subscript range information and avoiding the use of wrong subscripts, the problem of array out-of-bounds can be effectively avoided.

2. When using a for loop to access array elements sequentially, be sure to ensure that the subscript of the loop does not exceed the range of the array. You can avoid the array out-of-bounds problem by using the following code:

int[] array = new int[5];
for(int i=0; i

System.out.println(array[i]);

}

The number of loops here is the array length, which ensures that it will not exceed the array subscript range.

3. Use try-catch statement block to catch exceptions.

If you are developing a large-scale program, avoiding out-of-bounds problems can be difficult. At this time, you can use the try-catch statement to catch exceptions to ensure the normal operation of the program. For example:

int[] array = new int[5];
try{

int a = array[5]; //这里会产生越界异常

}catch(ArrayIndexOutOfBoundsException e){

System.out.println("数组下标越界！");

}

A try-catch statement block is used here to capture out-of-bounds exceptions and prompt information is given.

Summary:

The array subscript out-of-bounds problem in Java is a common problem in program development, but as long as we use the correct subscript or control the subscript range in the loop, This problem can be effectively avoided. If you encounter this problem, you can use try-catch statements and other methods to deal with it.

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