Algorithm of looking for “Equilibrium indexes” (Java)

This is small article about how to find all the equilibrium indexes in integer array. This is very efficient solution. Usually time of execution is O(n^2). This is solution for O(2*n)

@Test
public void verifyThatNumbersAreEquilibrium(){
    CodeBase codeBase = new CodeBase();
    int[] arrOfNumbers = new int[]{6,1,1,1,1,1,1,1};
  //int[] arrOfNumbers = new int[]{1,1,1,1,1,1,1,6};
    System.out.print(codeBase.getListOfEqIndexes(arrOfNumbers));
}

public List getListOfEqIndexes(int[] arr) {
    List list = new ArrayList();
    int tempSumLeft = 0;
    int sum = 0;
    for (int i = 0; i < arr.length; i++) {
        sum += arr[i];
    }

    int sumRight = sum - arr[0];

    for (int i = 0; i < arr.length; i++) {
        if(i-1 >=0) {
            tempSumLeft += arr[i - 1];
        }
        if (tempSumLeft == sumRight) {
            list.add(i);
        }
        if (i + 1 < arr.length) {
            sumRight -= arr[i + 1];
        }
    }

    return list;
}