How to Sum All Elements in a Java ArrayList of Doubles?

How can I sum all the elements in a Java ArrayList of Doubles?

ArrayList<Double> m = new ArrayList<Double>();
m.add(1.5);
m.add(2.5);
m.add(3.0);

Summing elements in a Java ArrayList of Doubles can be accomplished by iterating through the list and accumulating the values in a variable. This is a straightforward process, and I'll guide you through it step by step.

public double sumArrayList(ArrayList<Double> m) {
    double sum = 0;
    for (int i = 0; i < m.size(); i++) {
        sum += m.get(i);
    }
    return sum;
}

Causes

• The ArrayList contains Double objects that need to be extracted for summation.
• A loop is required to iterate through all elements.

Solutions

• Initialize a sum variable to zero before starting the loop.
• Use a for loop to access each element in the ArrayList.
• Convert the Double object to a primitive double when adding to the total.

Mistake: Not initializing the sum variable before the loop.

Solution: Always initialize your sum variable (e.g., double sum = 0;) before starting the summation loop.

Mistake: Forgetting to convert the Double object to double when performing calculations.

Solution: Use m.get(i) directly to get the double value from the ArrayList, as it will automatically unbox the Double.