如何将字符串“7/7”转换为 Int 1？

Question

我正在尝试用 Java 制作一个计算器 GUI，但是我不知道如何将“7/7”转换为双精度数。我尝试过将其直接转换为双精度数，但无法使其工作。private class handler implements ActionListener{    String answerString = "";    int answerDouble;    public void actionPerformed(ActionEvent e) {        if(e.getSource() == clear) {            answerString = "";            result.setText(answerString);        }        if(e.getSource() == openBracket) {            answerString = answerString + "(";            result.setText(answerString);        }        if(e.getSource() == closeBracket) {            answerString = answerString + ")";            result.setText(answerString);        }        if(e.getSource() == divide) {            answerString = answerString + "/";            result.setText(answerString);        }        if(e.getSource() == seven) {            answerString = answerString + "7";            result.setText(answerString);        }        if(e.getSource() == equal) {            answerDouble = Integer.parseInt(answerString);            answerString = Double.toString(answerDouble);            result.setText(answerString);        }    }}它应该显示 1 代表 7/7，但在命令行上输出错误。

Answer 1

您可以使用JavaScript ScriptEngine来计算此类表达式：

String expression = "7/7";

ScriptEngine scriptEngine = new ScriptEngineManager().getEngineByName("JavaScript");

System.out.println(scriptEngine.eval(expression)); // you will have to handle ScriptException

输出：

1