Is thıs code efficient always for finding array[max]?

Question

I am trying to find max value of an array, firstly i am shorting my array min to max after that i am using array[array.length-1] Is this logic efficient in large arrays?

public static int findMax(int[] array){

    Arrays.sort(array);

    int max = array[array.length-1];

    return max;
}//end method

Answer 1

No it's not.

Arrays.sort(array);

That line alone has an O(nlogn) running time. It can result in as many iterations as n, where n is the number of elements in the array, multiplied by log base 2 of n.

It would be much faster to just iterate through the array once.

public static int findMax(int[] array) {
    int indexOfMax = 0;
    for (i=1; i < array.length; i++) {
        if (array[i] > array[indexOfMax] {
            indexOfMax = i;
    }
    return indexOfMax
}

That has a maximum running time as O(n).

Answer 2

Cleaner implementation of the accepted answer:

public static int findMax(int[] array) {

    // TODO: Take appropriate action if the array is empty.

    int max_value = Integer.MIN_VALUE;

    for ( int value : array ) {
        if ( value > max_value ) {
            max_value = value;
        }
    }

    return max_value;
}