Java扫描仪输入读数

Question

I have the following input in 3 lines:

line 1: consists of positive int m and n separated by white space

line 2: list of m int separated by white space

line 3 and beyond: list of n words separated by white space or newline character

I am unable to read beyond m and n into my code

My Code:

Scanner input = new Scanner(System.in);
m = input.nextInt();
n = input.nextInt();
int[] lines = new int[m];
String[] words = new String[n];
input.nextLine();
for (int i = 0; i < m; i++) {
    lines[i] = input.nextInt();
}
for (int i = 0; i < n; i++) {
    words[i] = input.next();
}

How to read the line and words into the arrays after i call the first nextLine(), and try to read the numbers, i get a nullpointerexception

Answer 1

I think below is what you are looking for. Made small changes to your program. You don't really need line input.nextLine() . Hope it helps

Example Input

3 2
9 5 2
Good Luck

PROGRAM

Scanner input = new Scanner(System.in);

int m = input.nextInt();
int n= input.nextInt();

int[] lines = new int[m];
for (int i = 0; i < m; i++) {
    lines[i] = input.nextInt();
}

String[] words = new String[n];
for (int i = 0; i < n; i++) {
    words[i] = input.next();
}

Answer 2

I had the user insert the input one line at at time here. I'm not sure what you were looking for but this is what I have:

Program:

Scanner input = new Scanner(System.in);
System.out.print("Enter line 1: ");
int m = input.nextInt();
int n = input.nextInt();
System.out.println(m + " ints and " + n + " words");
System.out.print("Enter line 2: ");
int[] lines = new int[m];
String[] words = new String[n];
input.nextLine();
for (int i = 0; i < m; i++) {
    lines[i] = input.nextInt();
}
System.out.print("Enter line 3: ");
for (int i = 0; i < n; i++) {
    words[i] = input.next();
}
System.out.println(Arrays.toString(lines));
System.out.println(Arrays.toString(words));

Console:

Enter line 1: 3 4
3 ints and 4 words
Enter line 2: 1 2 3
Enter line 3: four words right here
[1, 2, 3]
[four, words, right, here]