java - 如何在不输出括号和逗号的情况下输出Arraylist中的数字列表？

Question

我有以下代码用于帮助我找到 1 和用户输入的任何内容之间的素数。唯一的问题是，我必须输出没有括号和逗号的数字。我该怎么做？

    System.out.println("\nLab1la\n");
    Scanner input = new Scanner(System.in);
    System.out.println("Enter the primes upperbond ==>> ");
    final int MAX = input.nextInt();
    boolean primes[];
    primes = new boolean[MAX];

    ArrayList<Integer>PrimeFactor = new ArrayList<Integer>();
    for (int i = 2; i < MAX + 1 ; i++)
    {
        PrimeFactor.add(i); 
    }


    CompositeNumbers(PrimeFactor);
    System.out.println("COMPUTING RIME NUMBERS");
    System.out.println();
    System.out.println("PRIMES BETWEEN 1 AND " + MAX);
    System.out.print(PrimeFactor);

}

public static void CompositeNumbers(ArrayList<Integer> PrimeFactor)
{
    for (int i = 0; i < PrimeFactor.size(); i++)
    {
        if (!isPrime(PrimeFactor.get(i)))
        { 
            PrimeFactor.remove(i);
            i--;

        }
    }
}

public static boolean isPrime(int n)
{
    if(n==1)
    {
        return true;
    }
    for (int i = 2; i < n +1/2; i++)
    {
        if (n%i == 0)
        {
            return false;

        }
    }
    return true;

}

}

Answer 1

依次输出每个值即可。例如:

// TODO: Rename PrimeFactor to primeFactors to follow Java naming conventions
for (int value : PrimeFactor)
{
    System.out.print(value);
    System.out.print(" "); // Or whatever separator you want
}

(这将在末尾输出一个额外的空格；摆脱它稍微繁琐，但不太难......)

或者使用像 Guava 的 Joiner 这样的东西类:

System.out.println(Joiner.on(' ').join(PrimeFactor));