如何在跑步者中将此数字列表设置为构造函数中的ArrayList？

Question

I've been struggling with this for a while now. I know that I can instantiate a String to an ArrayList in the constructo but I don't know how I would instantiate a group of ints to a ArrayList from the runner without doing it all manully using list.add(number) over and over again.

void setup() { //My runner
  NumAnalyzer test = new NumAnalyzer("5 12 9 6 1 4 8 6");

  out.println("even count = "+test.countEvens());
  out.println("odd count = "+test.countOdds());
  out.println("perfect count = "+test.countPerfects()+"\n\n\n");


  //add more test cases
}




import java.util.ArrayList;    
import java.util.Scanner;
import static java.lang.System.*;

public class NumAnalyzer{
  private ArrayList<Number> list;

  public NumAnalyzer(String word){
    list = new ArrayList<Number>(); //This instantiates it as a String but I want it to instantiate it as a list of integers. 
  }


  public int countOdds(){ //counting odds
      int oddCount=0;
      for(int x=0; x<list.size(); x++){
        if(list.get(x)%2 != 0){
          oddCount++;
        }
      }
      return oddCount;
  }

  public int countEvens(){ //counting evens
      int evenCount=0;
     for(Number num : list){
        if(list.get(num)%2 == 0){
           evenCount++;
        }
      }
      return evenCount;
  }

  public int countPerfects() {
     int perfectCount=0;
     for(int x=0; x<list.size(); x++){

       int mult=2, factorsum=0; //gets the sum of the multiples
       while(list.get(x) != mult){
         if(list.get(x)%mult == 0){
           factorsum=factorsum+list.get(x);
         }
         mult++;
       }

       if(factorsum == list.get(x)){ //testing to see if it's perfect
         perfectCount++;
       }
     }
     return perfectCount;
  }

  public String toString( ){





    return "Number of Odds:"+oddCount+"/n Number of Evens:"+evenCount+"/n Number of Perfects:"+perfectCount+list;
  }
}

Overall I just want the constructor to instantiate the ArrayList with the numbers from the runner.

Answer 1

In your constructor, you can split the word using spaces and then convert each token to an integer and finally collect to a list:-

list = Arrays.stream(word.split("\\s+"))
        .map(Integer::parseInt)
        .collect(Collectors.toList());

Update

For numbers instead of just integers, you can use this mapping:-

.map(s -> s.contains(".") ? (Number) Double.parseDouble(s) : Integer.parseInt(s))

If you strictly want ArrayList as opposed to any list, you can collect it as:-

.collect(Collectors.toCollection(ArrayList::new));

But it's better to use varargs if you are not working with Strings.

Answer 2

Why do you need a constructor with String if you're not willing to use it?

Varargs constructor will fit here well:

class NumAnalyzer {
    private List<Number> list;

    public NumAnalyzer(Number... numbers) {
        list = Arrays.asList(numbers);
    }
}

void setup() {
    NumAnalyzer test = new NumAnalyzer(5, 12, 9, 6, 1, 4, 8, 6);
}

Pay attention that it's much better design desicition to use private List<Number> list instead of private ArrayList<Number> list .

Moreover, this code will not compile because you're treating Numbers as Integers . If you're really expecting any type of number, passing them as a String will require more granular parsing.

Answer 3

1. You can remove all white spaces using replaceAll method and regexp or „ „.
2. Then, you can iterate over string chars and try to parse them into number.
3. After that, just add it to list of numbers.

However, You need to consider what happen if number has more than 1 digit