java - 在 Java 中，为什么我不能从超过 255 的十进制数中获取 9 个字符？是符号位吗？

Question

这是针对头尾 Java 作业的，您可以在网上找到几个地方(例如 http://www.javaproblems.com/2013/01/medium-problem-tricky-heads-and-tails.html )

这个想法是输入一个十进制 0 到 511，并让它输出一个 3 x 3 的 H 或 T 矩阵，表示 0 或 1(我的工作范围是 0 到 255)

这是我的尝试，但我无法工作:

public static void main(String[] args) {

    @SuppressWarnings("resource")
    Scanner keyboard = new Scanner(System.in);
    //System.out.println("Please enter a number between 0 and 511: ");
    //int num = keyboard.nextInt();
    int num = 458;
    String binNum = "";
    int temp;
    String[][] coinArr = new String[3][3]; // = [][];

    while(num > 0)
    {
        temp = (int) (num % 2);
        binNum = binNum + "" + temp;
        num = (int) (num / 2);
    }

    System.out.println("binNum length is " + binNum.length());
    System.out.println("binNum is " + binNum);

    binNum = String.format((binNum.length() < 9 ? ("%0"+ (9 - binNum.length())+"d%s") : "%0$d%s"), 0 ,binNum);
    System.out.println("binNum length is " + binNum.length());
    System.out.println("binNum is " + binNum);

    int k=0;
    for(int i = 0; i < 3; i++) {
        for (int j = 0; j < 3; j++) {
            binNum = binNum.replaceAll("0", "H");
            binNum = binNum.replaceAll("1", "T");
            coinArr[i][j] = binNum.substring(k, k+1);
            k++;
            System.out.print(coinArr[i][j]);
        }
        System.out.println();
    }
}

Answer 1

您从十进制到二进制的转换是错误的，正确的是:

while(num > 0)
{
    temp = (int) (num % 2);
    binNum = temp + "" + binNum;
    num = (int) (num / 2);
}

那么你的 binNum 中只需要 9 个字符:

binNum = binNum.length() < 9 ? String.format("%0"+ (9 - binNum.length())+"d%s", 0 ,binNum) : binNum;

// You don't need this inside your loop
binNum = binNum.replaceAll("0", "H");
binNum = binNum.replaceAll("1", "T");

int k=0;
for(int i = 0; i < 3; i++) {
    for (int j = 0; j < 3; j++) {
        coinArr[i][j] = String.valueOf(binNum.charAt(k));
        k++;
        System.out.print(coinArr[i][j]);
    }
    System.out.println();
}