如果我使用 bufferedreader 而不是扫描仪，相同的代码会给出运行时错误

Question

class Ideone
{
    public static void main (String[] args) throws java.lang.Exception
    {//BigInteger bi1, bi2, bi3;  
    long t,j,n;
    int i,x;

    BigInteger u,sum,temp,m;
    BigInteger[] a=new BigInteger[100009];  long[] b=new long[100009];
    long mm=1000000007,f;
        Scanner har=new Scanner(System.in);
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));           

        t=har.nextInt();
        for(f=0;f<t;f++)
        {   temp = BigInteger.valueOf(1);   sum = BigInteger.valueOf(0);    u = BigInteger.valueOf(0);              

                n=har.nextInt();    x=har.nextInt(); m=har.nextBigInteger();//String line = br.readLine();
    //String line = br.readLine(); // to read multiple integers line
        //String[] strs = line.trim().split("\\s+");
 //String[] s1 = br.readLine().split(" ");
 //StringTokenizer st = new StringTokenizer(br.readLine());
                for(i=1;i<=n;i++)
                {b[i]=har.nextInt();                

// b[i] = Integer.parseInt(st.nextToken());
//b[i] = Long.parseLong(System.console().readLine());    
//b[i]=Long.parseLong(s1[i-1]);
                }
        }
    }
}

input is of form 
t
n x m
a[1] a[2] a[3] .......a[n]

此代码在扫描仪上运行正常，但如果我尝试使用缓冲读取器或字符串标记器，则会出现运行时错误。 我是java新手，我需要使用大整数来解决问题的进一步部分。

Answer 1

您的代码没有任何问题。您将BufferReader 定义为BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); 并将String 定义为br.readLine();。

这个 sn-p 工作得非常好，并将输入字符串打印回控制台：

public static void main (String[] args)
{
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    System.out.println(br.readLine());
}

可能出现错误的一些可能性：

1. 字符串标记器

   StringTokenizer st = new StringTokenizer(br.readLine());
   

   在将其传递给StringTokenizer 之前，请确保您从br.readLine() 得到一个字符串。

   String text = br.readLine();
   if(!StringUtils.isEmpty(text)) {
       StringTokenizer st = new StringTokenizer(br.readLine());
       /* Rest of the code */
   }
   

2. 循环条件变量

   for(i=1;i<=n;i++)
   

   我没有看到初始化 n 的 BufferedReader 的任何内容。确保你正确初始化它。

这是一个快速代码sn-p：

public static void main (String[] args) throws Exception
{
    long j, n, f, mm = 1000000007;
    int i, x;
    BigInteger u, sum, temp, m;
    BigInteger[] a = new BigInteger[100009];  long[] b=new long[100009];

    Scanner har = new Scanner(System.in);

    long t = har.nextInt();
    for(f=0;f<t;f++)
    {   
        temp = BigInteger.valueOf(1);   
        sum = BigInteger.valueOf(0);    
        u = BigInteger.valueOf(0);
        n = har.nextInt();    
        x = har.nextInt(); 
        m = har.nextBigInteger();

        /* Goto Next Line */
        har.nextLine();

        /* Start Reading Line */
        String text = har.nextLine();
        System.out.println("String Value: " + text);
        if(null != text) {
            StringTokenizer st = new StringTokenizer(text);
            for(i = 1; i <= n; i++)
            {
                b[i] = Integer.parseInt(st.nextToken());
                System.out.println("Value of b[" + i + "] = " + b[i]);
            }
        }
    }
}