尝试，捕获并最终用于Scanner和BufferedReader的正确方法

问题描述

在我的主要方法中，尝试了解最好的和最有效的方法，以便最终尝试对Scanner和BufferedReader进行尝试。应该有两个不同的渔获物还是将它们组合成一个？

    public static void main(String[] args) throws IOException {
    //open file input stream
    try {
        BufferedReader reader = new BufferedReader(new FileReader("DATABASE.txt"));

        //read file line by line
        String line = null;
        Scanner scan = null;

        BST tree = new BST();
        line = reader.readLine();

        while(line != null) {
            Employee emp = new Employee();
            scan = new Scanner(line);
            scan.useDelimiter(",");

            while(scan.hasNext()){
                emp.setEmployeeID(Integer.parseInt(scan.next()));
                emp.setFirstName(scan.next());
                emp.setLastName(scan.next());
                emp.setSalary(Double.parseDouble(scan.next()));
                line = reader.readLine();
            }
            tree.insert(emp);
        }
        reader.close();
        tree.inorder();
        //System.out.println(empList);
    } catch(IOException e){
        e.printstacktrace();
    }

解决方法

一个捕获块就足够了。您可以添加一个finally块，该块将关闭阅读器和扫描器实例（如果它们不为空）。这样，无论try块正常完成还是引发异常，它们都将关闭。应该添加空检查，因为try块可能无法到达两个对象的初始化，否则可能会发生异常。

,

在try-catch-finally代码块外部声明了Scanner scan = null和BufferedReader reader = null;，并在try块内部对其进行了初始化。捕获到异常，它们都到达了finally块。

public static void main(String[] args) throws IOException {
    Scanner scan = null;
    BufferedReader reader = null;
    //open file input stream
    try {
        reader = new BufferedReader(new FileReader("DATABASE.txt"));

        //read file line by line
        String line = null;
        Scanner scan = null;

        BST tree = new BST();
        line = reader.readLine();
        scan = new Scanner(line);
        while (line != null) {
            Employee emp = new Employee();
            scan.useDelimiter(",");

            while (scan.hasNext()) {
                emp.setEmployeeID(Integer.parseInt(scan.next()));
                emp.setFirstName(scan.next());
                emp.setLastName(scan.next());
                emp.setSalary(Double.parseDouble(scan.next()));
                line = reader.readLine();
            }
            tree.insert(emp);
        }
    }catch (IOException e) {
        e.printStackTrace();
    } finally {
        reader.close();
        scan.close();
    }
}

,

您无需同时使用BufferedReader和Scanner。一个Scanner就足够了：

public static BST readFile(File file) throws FileNotFoundException {
    try (Scanner scan = new Scanner(file)) {
        scan.useLocale(Locale.US);  // mandatory for read double values

        BST bst = new BST();

        while (scan.hasNext()) {
            Employee employee = new Employee();
            employee.setEmployeeID(scan.nextInt());
            employee.setFirstName(scan.next());
            employee.setLastName(scan.next());
            employee.setSalary(scan.nextDouble());
            bst.insert(employee);
        }

        bst.inOrder();
        return bst;
    }
}