Summing elements in an Array List after adding a new element in net beans

Question

Summing elements of an array list right after adding a new element in net beans causes the first element added to not be counted in the sum.Then when i add another element it only sums the second element added.Code is below and there is an image of my problem.

https://gyazo.com/12f13ab5724af3de8d9848994987910d

private void balanceAddActionPerformed(java.awt.event.ActionEvent evt) {
    try {
        outputBox.setText("");
        String check = addInput.getText();
        int check1 = check.length();
        if ("".equals(check)) {
            errorLabel.setText("Nothing has been entered to be added.");
            for (int i = 0; i < balance.size(); i++) {
                outputBox.setText(outputBox.getText() + balance.get(i) + "\n");
            }
        } else if (check1 >= 7) {
            errorLabel.setText("Too many characters limit your characters to 7");
            addInput.setText("");
            for (int i = 0; i < balance.size(); i++) {
                outputBox.setText(outputBox.getText() + balance.get(i) + "\n");
            }
        } else {
            double list = Integer.parseInt(addInput.getText());
            balance.add(list);
            addInput.setText("");
            //Setting the array list in outputbox
            for (double i = 0; i < balance.size(); i++) {
                outputBox.setText(outputBox.getText() + balance.get((int) i) + "\n");
                errorLabel.setText("");
                double sum = 0;
                for (double j = 1; j < balance.size(); j++) {
                    sum += balance.get((int) j);

                    String converted = String.valueOf(sum);
                    errorLabel.setText("Your sum is " + (converted));
                }
            }
        }
    } catch (Exception e) {
        errorLabel.setText("Error wrong characters.");
        for (int i = 0; i < balance.size(); i++) {
            outputBox.setText(outputBox.getText() + balance.get(i) + "\n");
        }
    }
}

Answer 1

The main problem is that you are starting your summation loop at 1 which is why the first index 0 get's skipped:

for(int j=0; j<balance.size(); j++){
    sum += balance.get(j);      
}
String converted = String.valueOf(sum);
errorLabel.setText("Your sum is " + (converted) );

Other sidenotes:

• There is no need to declare j as a double (and then cast it back to an int )
• There is no need to update the label inside of the loop. You can do it once the loop is finished calculating the sum.

• To make the whole thing cleaner, you can use a for-each loop, since you don't need the index (and because ArrayList is iterable)

   for(double b: balance){ sum += b; }