在 Java 中从扫描仪读取双精度数不起作用

Question

编辑：弄清楚了，放错了一段代码

我有一个从文件计算斜率的程序。该文件的格式如下：

Y2“空间”Y1“空间”X2“空间”X1“空间”

我正在使用扫描仪从文件中读取字符串，然后将它们转换为双精度或整数。我这样做的原因是因为它似乎不从文本文件中仅读取字符串中的双精度数或整数。这是我的一些代码：

 modelSlopes.clear();
    modelValues.clear();
    int returnVal = openFileChooser.showOpenDialog(this);

    if (returnVal == JFileChooser.APPROVE_OPTION) {
        File file = openFileChooser.getSelectedFile();
        try {
            Scanner fileScanner = new Scanner(new FileReader(file));
            int count = 1;
            boolean suc = true;
            while (fileScanner.hasNext()) {
                suc = true;
                double tmp1 = 0;
                double tmp2 = 0;
                double tmp3 = 0;
                double tmp4 = 0;
                try {
                    if(count == 1) {
                        tmp1 = Double.valueOf(fileScanner.next());

                    }
                    if(count == 2) {
                        tmp2 = Double.valueOf(fileScanner.next());

                    }
                    if(count == 3) {
                        tmp3 = Double.valueOf(fileScanner.next());

                    }
                    if(count == 4) {
                        tmp4 = Double.valueOf(fileScanner.next());

                    }

                } catch (NumberFormatException e) {

                    try {
                        if(count == 1) {
                            tmp1 = Integer.valueOf(fileScanner.next());
                        }
                        if(count == 2) {
                            tmp2 = Integer.valueOf(fileScanner.next());
                        }
                        if(count == 3) {
                            tmp3 = Integer.valueOf(fileScanner.next());
                        }
                        if(count == 4) {
                            tmp4 = Integer.valueOf(fileScanner.next());
                        }
                    } catch(NumberFormatException e1) {
                        suc = false;
                    }
                }

                if(suc)  {
                    if(count != 4) {
                        count++;
                    }
                    if(count == 4) {
                        count = 1;
                        SlopeSolver tmpS = new SlopeSolver(Double.valueOf(tmp1), Double.valueOf(tmp2), Double.valueOf(tmp3), Double.valueOf(tmp4));
                        modelSlopes.addElement(tmpS.getSlope());
                        modelValues.addElement("Y2 - " + String.valueOf(tmp1) + "; Y1 - " + String.valueOf(tmp2) + "; X2 - " + String.valueOf(tmp3) + "; X1 - " + String.valueOf(tmp4));

                    }
                }
            }
        } catch (Exception e) {
            JOptionPane.showMessageDialog(this, "Error opening or with file");
        }
    } else {
    }

当我这样做时，它会显示斜率和值的 0。我似乎无法让它发挥作用。我是java新手，现在一无所知。任何帮助将不胜感激。

这是我正在读取数据的文本文件：

0.0 2.0 0.0 1.0

〜Andrew

Answer 1

我会简化代码

Scanner sc = new Scanner(new FileReader(file));
SlopeSolver ss = new SlopeSolver(sc.nextDouble(),
                              sc.nextDouble(), sc.nextDouble(), sc.nextDouble());
sc.close();

Answer 2

使用 fileScanner.nextDouble() 从用户输入中读取 double，使用 fileScanner.nextInt() 读取 int >。