Java采用多行输入

Question

How do I go about taking input that is multiple lines, such as

4 2 9
1 4 2
9 8 5

and placing it into an array of that is big enough to hold each line with no empty positions, or an arraylist. I've tried many ways to do this and cannot find a solution. For example, if the user copied and pasted the above snippet as input, I want an array or arraylist to hold

["4 2 9", "1 4 2", "9 8 5"] 

Answer 1

try this:

List<String> list = new ArrayList<String>();
 while((str = in.readLine()) != null){
 list.add(str);
}

Answer 2

You can use Scanner to read the input from console.

Try something like this:

public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    List<String> list = new ArrayList<String>();

    while(scan.hasNextLine()) {
        String str = scan.nextLine();
        System.out.println(str);
        list.add(str);
    }

    System.out.println(java.util.Arrays.toString(list.toArray()));

    scan.close();
}

Answer 3

Try calling nextLine

Scanner s = new Scanner(System.in);
ArrayList<String> list = new ArrayList<>();
while (s.hasNextLine()) {
    list.add(s.nextLine());
}

System.out.println(list);

Note that the scanner will keep prompting for input. To stop this, you need to enter an end of line character. See this answer for how to do this.

Example input/output:

4 2 9
1 4 2
9 8 5
^D
[4 2 9, 1 4 2, 9 8 5]