使用扫描仪读取一系列行时出现问题

I'm trying to read the input which is in the following format.

我正在尝试读取以下格式的输入。

2
asdf
asdf
3
asd
df
2

Following is the code:

以下是代码:

Scanner scanner = new Scanner(System.in);
int t = scanner.nextInt();
System.out.println(t);
while(t>0){

    String a = scanner.next();
    String b = scanner.next();
    int K = scanner.nextInt();
}

But when I'm scanning, I'm getting empty t=2 , a="" , b=asdf, K=asdf

但是当我正在扫描时,我变空了t = 2,a =“”,b = asdf,K = asdf

Can't figure out the issue. There is no space/new line between 2 and asdf.

无法弄清楚这个问题。 2和asdf之间没有空格/新行。

I have tried using scanner.nextLine() instead of scanner.next() but no change

我曾尝试使用scanner.nextLine()而不是scanner.next()但没有改变

2 个解决方案

#1

nextInt() doesn't cosume the newline token, so the following read will get it. You could introduce a nextLine after the nextInt to skip it:

nextInt()不会使用换行符号,因此以下读取将获取它。您可以在nextInt之后引入nextLine以跳过它:

Scanner scanner = new Scanner(System.in);
int t = scanner.nextInt();
scanner.nextLine(); // Skip the newline character
System.out.println(t);
while(t > 0) {
    String a = scanner.next();
    String b = scanner.next();
    int K = scanner.nextInt();
    scanner.nextLine(); // Skip the newline character
}

#2

Another approach I prefer:

我更喜欢另一种方法:

Scanner scanner = new Scanner(System.in);
int t = Integer.parseInt(scanner.nextLine());
System.out.println(t);
while(t>0){
     String a = scanner.nextLine();
     String b = scanner.nextLine();
     int K = Integer.parseInt(scanner.nextLine());
}

But note it will throw NumberFormatException when input is incorrect.

但请注意,当输入不正确时,它将抛出NumberFormatException。

#1