Java , Compute the alternating sum of all elements in an array, add even ones subtract odd ones

Compute the alternating sum of all elements in an array. For example, if your program reads the input 1 4 9 16 9 7 4 9 11 , then it computes

1 – 4 + 9– 16 + 9 – 7 + 4 – 9 + 11 = –2