Question

我有一个像这样的文本文件：

1 2
3 7
5 8

每行有2个数字。我想用第一个数字和第二个数字做一些不同的事情。我正在尝试扫描文本文件并打印数字以确保我正确扫描它。但是，只有前两个数字显示（1 4），然后出现错误：

"java.util.NoSuchElementException
    at java.base/java.util.Scanner.throwFor(Scanner.java:858)
    at java.base/java.util.Scanner.next(Scanner.java:1497)
    at java.base/java.util.Scanner.nextInt(Scanner.java:2161)
    at java.base/java.util.Scanner.nextInt(Scanner.java:2115)
    at com.company.SCC.input(SCC.java:30)
    at com.company.SCC.<init>(SCC.java:15)
    at com.company.Main.main(Main.java:11)"

我不明白问题是什么以及如何逐行扫描文档（我回收了扫描仪的代码，之前它正在运行）。我不确定我做错了什么，任何帮助都会受到赞赏。

try {
        String file = "testcase1.txt";
        FileReader in = new FileReader(file);
        BufferedReader br = new BufferedReader(in);
        String s;
        int x;
        while ((s = br.readLine()) != null) {
            Scanner sca = new Scanner(s);
            x = sca.nextInt();
            graph.addVertex(x);
            int y = sca.nextInt();
            graph.addAdjvex(x, y);
            System.out.println(x + " " + y);
        }

    } catch (Exception e) {
        e.printStackTrace();
    }

Answer 1

尝试

try {
    File file = new File("testcase1.txt");
    Scanner sc = new Scanner(file);
    int x, y;
    while (sc.hasNextLine()) {
        x = sc.nextInt();
        y = sc.nextInt()
        graph.addVertex(x);
        graph.addAdjvex(x, y);
        System.out.println(x + " " + y);
    }
    sc.close();
} catch (Exception e) {
    e.printStackTrace();
}

Answer 2

try {
    File file = new File("testcase1.txt");
    Scanner sc = new Scanner(file);
    while (sc.hasNextLine()) {
        int x = sc.nextInt();
        int y = sc.nextInt();
        sc.nextLine();
        graph.addVertex(x);
        graph.addAdjvex(x, y);
        System.out.println(x + " " + y);
    }
    sc.close()

} catch (Exception e) {
    e.printStackTrace();
}

Answer 3

也许你应该调用sc.nextLine（）来跳转到下一行

Scanner Java只是阅读第一行

3 个答案: