java - Java 中的 BigInteger 扫描器输入

Question

我只想从Java的扫描仪输入中获取BigInteger，但循环超出了它的限制。如果我想获得两倍的输入，则循环会获得两次，但只打印一次。我想要获取输入并将输入相乘并显示结果。

import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Scanner;

public class Fastmultiplication {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        BigInteger m = BigInteger.valueOf(1);
        BigInteger n = BigInteger.valueOf(1);
        Scanner sc = new Scanner(System.in);
        Scanner sc1 = new Scanner(System.in);
        int in = sc.nextInt();

        ArrayList<BigInteger> al = new ArrayList<BigInteger>();

        while ((sc.hasNextBigInteger()) && (sc1.hasNextBigInteger()) && (in != 0)) {
            in--;
            m = sc.nextBigInteger();
            n = sc1.nextBigInteger();
            al.add(m.multiply(n));

        }
        System.out.println(al.size());
        for (BigInteger integer : al) {

            System.out.println(integer);

        }
        sc.close();
        sc1.close();
    }
}

Answer 1

我不明白您为什么创建两个 Scanner 对象。但这里是所需的工作代码:

import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Scanner;

public class Fastmultiplication {
    public static void main(String[] args) {
        BigInteger m, n;
        try (Scanner sc = new Scanner(System.in)) {
            int in = sc.nextInt();

            ArrayList<BigInteger> al = new ArrayList<>();
            while (in > 0) {
                in--;
                m = sc.nextBigInteger();
                n = sc.nextBigInteger();
                al.add(m.multiply(n));
            }

            al.stream().forEach((bigInteger) -> {
                System.out.println(bigInteger);
            });
        } catch (Exception e) {
            System.out.println("Invalid user input.Going to terminate this program");
        }
    }
}