利用charArray反求整数

Question

我的密码怎么了？我想逆转，例如1234到4321，它没有工作！

public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int num = in.nextInt();

        for (int i =0; i < num; i++){
            int n = in.nextInt();
            char[] ch = ("" + n).toCharArray();
            for (int j = 0; j < ch.length; j ++){
                char temp = ch[j];
                ch[j] = ch[ch.length - 1 -j];
                ch[ch.length - 1 -j] = temp;

                System.out.print(ch + " ");
            }

Answer 1

这应该能行

public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int num = in.nextInt();

        for (int i =0; i < num; i++){
            int n = in.nextInt();
            string ch = n.toString();
            string output = "";
            for (int j = 0; j < ch.length; j ++){
                output = ch[j] + output;
            }
            System.out.println(output);
        }
}

Answer 2

我想这是个简单的方法，

Scanner in = new Scanner(System.in);
int num = in.nextInt();
String reverse = new StringBuilder((num + "")).reverse().toString();
System.out.println(reverse);

Answer 3

在您的代码中有一些问题：

1. 您已经从用户那里获得了两次输入。
2. 在try-with-resource中使用Scanner以避免源泄漏。
3. 您已经遍历了整个数组的length，您只需要它的一半。
4. 您不能用char[]打印toString()数组，因为它将返回数组对象的引用，因此必须遍历数组并按一个数组进行打印，或者使用Arrays.toString()。

try (Scanner input = new Scanner(System.in)) {
    int num = input.nextInt();
    char[] numChars = ("" + num).toCharArray();
    for (int j = 0; j < numChars.length / 2; j++) {
        char temp = numChars[j];
        numChars[j] = numChars[numChars.length - 1 - j];
        numChars[numChars.length - 1 - j] = temp;
    }

    for (char c : numChars) {
        System.out.print(c + " ");
    }
    // Or you can use this instead of the above for loop.
    // System.out.print(Arrays.toString(numChars));
}