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/**

 * @param args the command line arguments

 */

public static void main(String args) {

    int x;

    x= new int [3];

    x[0]=4;

    x[1]=1;

    x[2]=2;

    x[3]=3;

    x=sortArray (x);

    System.out.println (x[2]);

}



public static int indexOfMaxInRange(int A, int i){

    int maxIndex=A[0];

    while (i < A.length) {

        if (A[i]>maxIndex){

            maxIndex= A[i];

        }

        i++;

    }

    return maxIndex;

}



 public static int swapElement (int A,int i1,int i2) {

    int i1value=A[i1];

    int i2value=A[i2];

    A[i1]=A[i2value];

    A[i2]=A[i1value];

    return A;

}



 public static int sortArray (int A) {

    for (int i = 0; i < A.length; i++) {

        int x=indexOfMaxInRange (A,i);

        swapElement (A,x,i);

    }

    return A;

}

This keeps on returning on with an error.
I can't seem to find what's wrong with my program.
The objective of the program is to sort an array highest from lowest.

Let's start off with x[3] = 3. Since you declared x to be of size 3, your max index would be 2. That was probably your original error, ArrayIndexOutOfBoundsError - which basically means you are trying to assign a value to an index of the array that is not within the range of [0, len(array) - 1]. So, either increase the size of the array or don't assign an element to index 3.

Also, for future reference, letting us know what error you get would be helpful.

When calling functions, try to not have a space between the function name and the opening parenthesis. It will still compile, I believe, but it is weird to read. Also, add spaces around the equals sign. For example:

int x=indexOfMaxInRange (A,i);

should be:

int x = indexOfMaxInRange(A,i);

From what I gather you are implementing selection sort, where you get the max of the whole array, place it as the first element, and find the highest of the array while ignoring the first element and placing that element as the second element in the array. And so on and so forth.

Your swap function looks good as does your sortArray function, however, your indexMaxOfRange function is incorrect. I will leave you to fix that function for yourself, but I will say that indexMaxOfRange is expecting an index to be returned, and at no place in that function are you assigning maxIndex to be an index.

You have several problems with your code. You seem to be confusing elements with index positions. When you have:

int maxIndex=A[0];

while (i < A.length) {

    if (A[i]>maxIndex){

        maxIndex= A[i];

    }

    i++;

}

return maxIndex;

You are returning the largest element in the Array, not the index of the largest element of the Array. Then you use this to call

swapElement (A,x,i);

(Where x is what is returned by the above method) Which is extremely likely to throw an out of bounds error. Think if the largest element was 1 million. You'd be calling the one millionth index of A

Also you initialize your Array with a size of 3, and try to put four elements into it. Array index's start at zero, so in an Array of size 3, the last index will be 2.

You need to change it so that the index, and the element at that index are separate. A simple solution would be to have a separate variable for the element and index. When the element is bigger than the current biggest element, set the index equal to i and the greatest element equal to the new bigger element:

public static int indexOfMaxInRange(int A, int i){

    int maxIndex = 0;

    int maxElement = 0;

    while(i < A.length) {

       if(A[i]>maxElement){

          maxElement = A[i];

          maxIndex= i;

       }

       i++;

   }

   return maxIndex;

}

Lastly in your call:

swapElement (A,x,i);

You want to be shifting the greatest element (The element at index x) over, so you need to do swapElement(A,x,i + 1);

Since you will be swapping one ahead you only need to loop until:

for(int i = 0; i < A.length-1; i++) 

When called as:

int x= new int [4];

x[0]=4;

x[1]=1;

x[2]=2;

x[3]=3;

x=sortArray(x);

System.out.println(Arrays.toString(x));

It produces the output:

[1, 2, 3, 4]