private void compute(Calculator.Operator operator) {
        double operandOne;
        double operandTwo;
        try {
            operandOne = getOperand(mOperandOneEditText);
            operandTwo = getOperand(mOperandTwoEditText);
        } catch (NumberFormatException nfe) {
            Log.e(TAG, "NumberFormatException", nfe);
            mResultTextView.setText(getString(R.string.computationError));
            return;
        }

        String result;
        switch (operator) {
            case ADD:
                result = String.valueOf(mCalculator.add(operandOne, operandTwo));
                break;
            case SUB:
                result = String.valueOf(mCalculator.sub(operandOne, operandTwo));
                break;
            case DIV:
                result = String.valueOf(mCalculator.div(operandOne, operandTwo));
                break;
            case MUL:
                result = String.valueOf(mCalculator.mul(operandOne, operandTwo));
                break;
            default:
                result = getString(R.string.computationError);
                break;
        }
        mResultTextView.setText(result);
    }
OnClick method that is called when the multiply {@link Button} is pressed.
runner/AndroidTestOrchestratorSample/app/src/main/java/com/example/android/testing/androidtestorchestratorsample/CalculatorActivity.java