How to implement a binary search in java in bluej?

Question

I have this but the method isn't showing up on the object created in bluej. How can an do a binary search on an int array then output the found int?

public static int binarySearch(int a[], int element)
{
    int first = 0;
    int upto = a.length;

    while (first < upto) 
    {
        int mid = (first + upto) / 2;  // Compute mid point.
        if (element < a[mid]) 
        {
            upto = mid;                // repeat search in bottom half.
        } else if (element > a[mid]) 
            {
                first = mid + 1;       // Repeat search in top half.
            } 
                else 
                {
                    return mid;        // Found it. return position
                }
            }
     return -(first + 1);              // Failed to find key
  }  

Answer 1

You made the method static . Therefore it most likely appears in the context menu of the class not of the object .

Answer 2

If you always returned found the int you are looking for, you would just return element every time. There would be no point doing a search. This method returns the index of the elements or the negative of the place it is inserted.

BTW: This code example has an old bug in the

int mid = (first + upto) / 2

which should read

int mid = (first + upto) >>> 1;

as it does in Arrays.binarySearch();