输出一个JAVA函数，函数的入参为数据表达式，如入参为如 -2*3*-4 则函数的输出为@2*3*@4

你可以创建一个名为`evaluateExpression`的Java函数，它接受一个字符串作为输入，该字符串代表一个数学表达式，然后使用递归解析和计算来得到结果。这里是一个简单的示例，使用了栈来处理运算符优先级：

import java.util.Stack;

public class ExpressionEvaluator {

    private static final int PRECEDENCE_MULTIPLICATION = 2;
    private static final String OPERATOR_MULTIPLICATION = "*";
    
    public static double evaluate(String expression) {
        return new ExpressionParser(expression).calculate();
    }

    private static class ExpressionParser {
        
        private String input;
        private Stack<Integer> operatorsStack = new Stack<>();
        private StringBuilder resultBuilder = new StringBuilder();

        public ExpressionParser(String expression) {
            this.input = expression;
        }

        private double calculate() {
            parseInput();
            return Double.parseDouble(resultBuilder.toString());
        }

        private void parseInput() {
            for (char c : input.toCharArray()) {
                if (Character.isDigit(c)) {
                    addNumber(c);
                } else if (c == '+' || c == '-') {
                    handleOperator('+');
                } else if (c == '*' || c == '/') {
                    handleOperator(PRECEDENCE_MULTIPLICATION);
                } else if (c == '(') {
                    operatorsStack.push(PRECEDENCE_MULTIPLICATION);
                } else if (c == ')') {
                    while (!operatorsStack.isEmpty() && operatorsStack.peek() != '(') {
                        handleOperator(operatorsStack.pop());
                    }
                }
            }
            while (!operatorsStack.isEmpty()) {
                handleOperator(operatorsStack.pop());
            }
        }

        private void handleOperator(int precedence) {
            if (resultBuilder.length() > 0) {
                resultBuilder.append(' ');
            }
            double right = Double.parseDouble(resultBuilder.toString());
            resultBuilder.setLength(0);
            resultBuilder.append(evaluateRightmost());
            resultBuilder.append(OPERATOR_MULTIPLICATION);
            resultBuilder.append(right);
        }

        private double evaluateRightmost() {
            if (operatorsStack.isEmpty() || operatorsStack.peek() < precedence MULTIPLICATION) {
                return Double.parseDouble(resultBuilder.toString());
            }
            double left = evaluateRightmost();
            resultBuilder.deleteCharAt(resultBuilder.length() - 1); // remove the last operator
            resultBuilder.append(left);
            return left;
        }

        private void addNumber(char digit) {
            resultBuilder.append(digit);
        }
    }
}