Kalkulator wartości z pliku - problem z algorytmem

//Właściwy kod
public static void main(String[] args) {
        FileOperator fileOperator = new FileOperator("calculations.txt");
        ArrayList<Operation> instructions = new ArrayList<>();

        String line;
        try {
            while ((line = fileOperator.getReader().readLine()) != null) {
                String[] operation = line.split(" ");
                instructions.add(new Operation(operation[0], Integer.parseInt(operation[1])));
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

        int result = 1;
        int lastValue;
        for (Operation operation : instructions) {
            switch (operation.getOperation()) {
                case OperationStringConstants.ADD -> result += operation.getValue();
                case OperationStringConstants.SUBTRACT -> result -= operation.getValue();
                case OperationStringConstants.DIVIDE -> {
                    int value = operation.getValue();
                    if (value != 0) {
                        result /= value;
                    }
                }
                case OperationStringConstants.MULTIPLY -> result *= operation.getValue();
                case OperationStringConstants.APPLY -> lastValue = operation.getValue();
            }
        }
      result += lastValue
    }
//=====
class OperationStringConstants {
    public static final String ADD = "add";
    public static final String SUBTRACT = "subtract";
    public static final String MULTIPLY = "multiply";
    public static final String DIVIDE = "divide";
    public static final String APPLY = "apply";
}

class Operation {
    private String operation;
    private int value;

    public Operation(String operation, int value) {
        this.operation = operation;
        this.value = value;
    }

    public String getOperation() {
        return operation;
    }

    public int getValue() {
        return value;
    }
}

class FileOperator {
    private final String fileName;
    private BufferedReader reader;

    public FileOperator(String fileName) {
        InputStreamReader streamReader =
                new InputStreamReader(getFileFromResourceAsStream(fileName), StandardCharsets.UTF_8);
        this.fileName = fileName;
        reader = new BufferedReader(streamReader);
    }

    private InputStream getFileFromResourceAsStream(String fileName) {
        ClassLoader classLoader = getClass().getClassLoader();
        InputStream inputStream = classLoader.getResourceAsStream(fileName);
        if (inputStream == null) {
            throw new IllegalArgumentException("file not found! " + fileName);
        } else {
            return inputStream;
        }
    }

    public String getFileName() {
        return fileName;
    }

    public BufferedReader getReader() {
        return reader;
    }
}

public class InstructionChain {
    private List<Instruction> chain = new ArrayList<>();

    public int apply(final int operand) {
        // wykonuje wszystkie kroki z łańcucha instrukcji
    }

    public void addStep(final String line) {
        // parsuje linię i dodaje obiekt Instruction do listy instrukcji
    }

    private enum Operator {
        ADD((result, value) -> result+value),
        SUBTRACT((result, value) -> result-value),
        MULTIPLY((result, value) -> result*value),
        DIVIDE((result, value) -> result/value);

        private final IntBinaryOperator accumulator;
        Operator(final IntBinaryOperator accumulator) {
            this.accumulator = accumulator;
        }
    }

    private class Instruction {
        private final Operator operator;
        private final int value;

        private Instruction(final Operator operator, final int value) {
            this.operator = operator;
            this.value = value;
        }

        private int apply(final int operand) {
            return operator.accumulator.applyAsInt(operand, value);
        }
    }
}