如何在Java中的字符串中的空格之间导出数字？

Question

I want to input a String like this "5 4 34" from keyboard. How can I export the numbers between spaces? Also a want to export them into an int[] array, and print them on the screen.

Answer 1

You can use String.split("\\\\s") to split the String to String[] and then use Integer.parseInt() on each element to get the number as an int .

Alternatively, you can use a Scanner , and its nextInt() method

Since the others have already showed you how it can be done with split() , here is an example how to do it with Scanner , directly from System.in (I am assuming that what you want, because you say you read it from keyboard, of course you can use any Readable or a String to build your Scanner ):

Code:

Scanner inputScanner = new Scanner(System.in);
Scanner scanner = new Scanner(inputScanner.nextLine());
List<Integer> list = new ArrayList<Integer>();
while (scanner.hasNextInt()) {
    list.add(scanner.nextInt());
}
Integer[] arr = list.toArray(new Integer[0]);

or if you want an int[] and not an Integer[] instead of the last line, use:

int[] arr = new int[list.size()];
int i = 0;
for (Integer x : list) { 
    arr[i++] = x;
}

To print the array just print the result of Arrays.toString() :

System.out.println(Arrays.toString(arr));

Answer 2

Add an exception handler and you're in good shape:

String values = "5 4 34";
String [] tokens = values.split("\\s+");
List<Integer> numbers = new ArrayList<Integer>();
for (String number : tokens) {
    numbers.add(Integer.valueOf(number);
}

Or like this:

String values = "5 4 34";
String [] tokens = values.split("\\s+");
int [] numbers = new int[tokens.length];
for (int i = 0; i < tokens.length; ++i) {
    numbers[i] = Integer.valueOf(tokens[i]);
}

Answer 3

    String[] stringArray = "5 4 34".split( " " );
    int[] intArray = new int[ stringArray.length ];

    for ( int i = 0 ; i < stringArray.length ; i++ )
    {
        intArray[ i ] = Integer.parseInt( stringArray[ i ] );
    }

Answer 4

String string = "5 4 34";
String[] components = string.split(" "); // [5, 4, 34]

Answer 5

Without much boilerplate:

List <Integer> numbers = new ArrayList <Integer> ();
for (String number : "5 4 34";.split ("\\s+")) {
    int v = Integer.parseInt (number);
    System.out.println (v);
    numbers.add (v);
}

Or using Scanner:

Scanner scanner = new Scanner ("5 4 34");
List <Integer> list = new ArrayList <Integer> ();
while (scanner.hasNextInt()) {
    int v = scanner.nextInt ();
    list.add (v);
    System.out.println (v);
}