拆分成对数字的字符串，然后在 java 中拆分每个数字

Question

lets say I have the following line:

ball_velocities:45,500 46,500 47,500

I would like to:

• split the pairs from each other
• split the the pair itself and the numbers inside of it from each other use both of those numbers in a function that I already have

 String[] numbers = data.split("\\\\s+"); if (numbers.length > 0) { List<Velocity> velocities = new ArrayList<>(); for (String number: numbers) { try { int firstNum = Integer.parseInt(number); int secondNum = Integer.parseInt(number); velocities.add(Velocity.pair(firstNum,secondNum));

I know I have messed it up, so I'll be glad to hear some suggestions.

I think it's pretty simple, all I gotta do is to data.split by spaces as I already did data split again by comma and then I don't know how to combine those 2 numbers into one function.

I mean in the end I want it to be: a list of velocities that contain the values of:

Velocity.pair(45,500)
Velocity.pair(46,500)
Velocity.pair(47,500)

Thanks.

Answer 1

Assuming the class Velocity looks like this:

class Velocity {
    private int firstNumber;
    private int secondNumber;

    public Velocity(int firstNumber, int secondNumber) {
        super();
        this.firstNumber = firstNumber;
        this.secondNumber = secondNumber;
    }

    public int getFirstNumber() {
        return firstNumber;
    }

    public void setFirstNumber(int firstNumber) {
        this.firstNumber = firstNumber;
    }

    public int getSecondNumber() {
        return secondNumber;
    }

    public void setSecondNumber(int secondNumber) {
        this.secondNumber = secondNumber;
    }

    public String toString() {
        return "[" + firstNumber + ", " + secondNumber + "]";
    }
}

you will basically have to go step by step:

1. remove the introducing tag ball_velocities: from the String you want to split,
2. split the result by an arbitrary amount of whitespaces, then
3. split each result of that by comma,
4. parse the results to int s
5. instantiate a Velocity with the results of the parsing and finally
6. add each instance of Velocity to the List<Velocity>

which can be done as follows, for example:

public static void main(String[] args) throws ParseException {
    String data = "ball_velocities:45,500 46,500 47,500";

    List<Velocity> velocities = new ArrayList<>();
    // remove the intro tag and then split by whitespace(s)
    String[] numberPairs = data.replace("ball_velocities:", "").split("\\s+");

    // handle each result (which still consists of two numbers separated by a comma
    for (String numberPair : numberPairs) {
        // that means, split again, this time by comma
        String[] numbers = numberPair.split(",");
        // parse the results to ints
        int firstNum = Integer.parseInt(numbers[0]);
        int secondNum = Integer.parseInt(numbers[1]);
        // instantiate a new Velocity with the results and add it to the list
        velocities.add(new Velocity(firstNum, secondNum));
    }

    // print the list using the `toString()` method of Velocity
    velocities.forEach(System.out::println);
}

This example will print

[45, 500]
[46, 500]
[47, 500]

Answer 2

Assuming that you have a string of data with velocity information, you can use the following snippet:

@Getter
@Setter
@AllArgsConstructor
@ToString
public class Velocity {
    int id1;
    int id2;

    static Velocity pair(int i1, int i2) {
        return new Velocity(i1, i2);
    }
}
// -------- testing
String input = "ball_velocities:45,500 46,500 47,500";
String velo = input.replaceAll("ball_velocities\\s*\\:\\s*", ""); //remove prefix containing optional whitespaces

// String velo = "45,500 46,500 47,500";

Arrays.stream(velo.split("\\s+"))
      .map(s -> s.split("\\,"))
      .map(a -> Velocity.pair(Integer.parseInt(a[0]), Integer.parseInt(a[1])))
      .collect(Collectors.toList()) // list of velocity is available here
      .forEach(System.out::println);

output:

Velocity(id1=45, id2=500)
Velocity(id1=46, id2=500)
Velocity(id1=47, id2=500)

Answer 3

First let's get the inputs into a String array:

String[] inputs = data.split(":")[1].split(" ");

Essentially we get the right-most part of the colon first and split that into an array of String items, which represent the input you have, having values like "45,500". Let's create a Velocity array and fill it with items:

Velocity[] velocities new Velocity[inputs.length];

for (int index = 0; index < inputs.length; index++) {
    String parts = inputs[index].split(",");
    velocities[index] = new Velocity(parts[0], parts[1]);
}