如何修改主方法以从命令行获取输入和输出

Question

不是硬编码来读取infile和outfile，我想从命令行读取。我该怎么做呢?

/**
 * reads a file and creates a histogram from it
 * @param args string of argument
 * @precondition none
 */
public static void main(String[] args) {
    Histogram hist = new  Histogram();
    FileInputController input = new FileInputController(hist);
    FileOutputController output = new FileOutputController(hist);
    try {
        input.readWords("infile.txt");
        output.writeWords("outfile.txt");
    } catch (FileNotFoundException exception) {
        System.out.println("exception caught! somthing went wrong: " + exception.getMessage());
    } catch (IOException exception) {
        System.out.println("exception caught! somthing went wrong: " + exception.getMessage());
    } finally {
        System.exit(1);
    }
 }

Answer 1

public static void main(String[] args) {
    WordHistogram hist = new  WordHistogram();
    FileInputController input = new FileInputController(hist);
    FileOutputController output = new FileOutputController(hist);
    try {
        input.readWords(args[0]);  //args[0] is the first argument passed while launching Java
        output.writeWords(args[1]);  //args[1] is the second argument passed while launching Java
    } catch (FileNotFoundException exception) {
        System.out.println("exception caught! somthing went wrong: " + exception.getMessage());
    } catch (IOException exception) {
        System.out.println("exception caught! somthing went wrong: " + exception.getMessage());
    } finally {
        System.exit(1);
    }
}

运行程序:java YourClassName infile.txt outfile.txt

在main(String[] args)中，args是一个字符串数组，其中包含启动Java时传递的参数值。

请务必阅读Oracle文档中关于命令行参数的详细信息

Answer 2

获取整数值

Scanner sc = new Scanner(System.in);
int i = sc.nextInt();

使用

获取字符串

Scanner scanner = new Scanner(System.in);
String username = scanner.nextLine();

和输出只使用System.out.println("your text here");