使用扫描仪读取一系列行时出现问题

Question

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

2
asdf
asdf
3
asd
df
2

Following is the code:

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

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

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

Answer 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:

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
}

Answer 2

Another approach I prefer:

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.