如何在没有 ArrayIndexOutOfBoundsException 的情况下添加到数组？

Question

Can anyone answer this question?

public class AddingArray {
  public static void main(String[] args){
      int arry1[] = {2,3,4,5,6,7,9};
      int arry2[] = {4,3,7,9,3,5};

      for(int i = 0; i <arry1.length; i++){
          int result = arry1[i] + arry2[i];
          System.out.println("Result "+result);
      }
   }
}

Whenever I try executing the above code I get the error Exception in

thread "main" java.lang.ArrayIndexOutOfBoundsException: 6   at
basics.AddingArray.main(AddingArray.java:9)

But,my output should be like this 6,6,11,14,9,12,9

Answer 1

It is because your loop will go from 0 to 6 (which is the array1.length - 1 ) and your array2 only has 6 elements (so from 0 to 5 ).

So when you are accessing arry2[6]; It will give you the java.lang.ArrayIndexOutOfBoundsException .

You could change your for loop to go to the length of the smallest array:

for(int i = 0; i < arry2.length; i++){ /*Do what you want */ }

Or add an element in array2 , but that is yours to decide since I do not know your requirements.

Answer 2

As people have mentioned, one of yours arrays is literally shorter than the other. Take two blocks and overlay them over only one block. The second (in this case index 1 block) would fall into the abyss, because the block that was supposed to catch it never existed.

I would make sure both of them are of the same size. If you do want to leave em as they are, I would do this:

int result = 0;

try
{
   for(int i = 0, length = array2.length; i < length; i++)
   {

      result = array1[i] + array2[i];
      System.out.println("Result is: " + result);

    }
    catch(Exception e)
    {
       System.out.println("You tried to do something that resulted in an error");
       System.out.println("Your previous result was: " + result);
    }
 }

SO, assuming that I still recall how to do basic arrays, what this code will do is that it will catch any errors thrown by your code.

Answer 3

Let's make this as simple and understandable as possible, with no fancy annotations:

1. You have two int arrays, of not equal lengths, and you wish to add the index-paired numbers to an array of the sums. However, if one of the arrays does not have any more numbers, the value of the longest array will be the result.

    public class AddingArray { public static void main(String[] args){ int arry1[]={2,3,4,5,6,7,9}; int arry2[]={4,3,7,9,3,5};

You need to determine the length of the longest array. You can do this with a Math.max() -method, where you give the length of each array as parameters:

      int biggestArrayLength = Math.max(arry1.length, arry2.length);

Then, instead of for(int i=0;i<arry1.length;i++){ , you write:

      for(int i=0;i<biggestArrayLength;i++){

Now it doesn't matter which of the two arrays is the biggest one.

Inside the loop, I would define two ints, representing a value from each of the two arrays:

      int value1 = arry1[i];
      int value2 = arry2[i];

however, this will give an error when the smallest array does not have any more elements. We need to check if the array actually has an element with index i. index numbers in arrays start with 0. so if the length is 7, the 7 elements will have index numbers from 0-6. In other words, only index numbers that are lower (and not equal) to length, is valid numbers:

      int value1 = 0;
      int value2 = 0;

      if(arry1.length > i){
          value1 = arry1[i];
      }
      if(arry2.length > i){
          value2 = arry2[i];
      }

      int result = value1 + value2;
      System.out.println("Result "+result);
  }

} }

Now, if you need to put these in a third array, say named sumArray, this would be the complete code:

public class AddingArray {
  public static void main(String[] args){
      int arry1[]={2,3,4,5,6,7,9};
      int arry2[]={4,3,7,9,3,5};

      int biggestArrayLength = Math.max(arry1.length, arry2.length);

      int[] sumArray = new int[biggestArrayLength];
      for(int i=0;i<biggestArrayLength;i++){

          int value1 = 0;
          int value2 = 0;
          if(arry1.length > i){
              value1 = arry1[i];
          }
          if(arry2.length > i){
              value2 = arry2[i];
          }

          int result = value1 + value2;
          sumArray[i] = result;
          System.out.println("Result "+result);
      }
   }
}

Answer 4

Because arry1 is longer than arry2 when you make the last iteration through the loop arry2[i] returns null because there is no element to return. either do: if(arry2[i] != null) { //run your adding code } or change your arrays to be the same size

Answer 5

Edit: The reason it is not working properly is because you are using the length of the largest array as the conditional within the for loop. This condition allows you to attempt to access the 2nd array at a location that does not exist, which is why you are getting an ArrayIndexOutOfBoundsException .

Can we stop the downvoting?

End edit----

If you want to add up all of the elements in the array use this code.

    public class AddingArray {
      public static void main(String[] args){
          int arry1[]={2,3,4,5,6,7,9};
          int arry2[]={4,3,7,9,3,5};
          int result = 0;

          for(int i=0;i<arry1.length;i++){
              result+=arry1[i];
          }
          for(int j=0; j < array2.length; j++){
              result += array2[j];
          }

          System.out.println("Result: "+ result);
      }
}

if you are trying to sum individual elements as you loop you can do the following. This will properly handle 2 arrays of different length regardless of which one is longer.

    public class AddingArray {
      public static void main(String[] args){
          int arry1[]={2,3,4,5,6,7,9};
          int arry2[]={4,3,7,9,3,5};
          int result = 0;
          for(int i=0;i<arry1.length;i++){
              result=arry1[i];
              if(i < array2.length){
                 result += array2[i];
              }
              System.out.println("Result: "+ result);
          }
          for(int j = i; j < array2.length; j++){
              System.out.println("Result: "+ array2[j]);
          }

      }
}