java - 在 Java 中使用递归将字符串转换为反向字符串

Question

今天我试图将字符串转换为反向字符串例如(Cat Is Running 变成 Running Is Cat) 逐字而不是字符

public class ReverseString_ {
    public static void reverse(String str) {
        String[] a = str.split(" ");
        for (int i = a.length - 1; i >= 0; i--) {
            System.out.println(a[i] + " ");
        }
    }

    public static void main(String[] args) {
        reverse("Cat Is Running");
    }
}

显示以下输出:

Running Is Cat BUILD SUCCESSFUL (total time: 0 seconds)

我试图将字符串转换为与上面相同的反向字符串，但通过递归方法，但它似乎太困惑了。并显示更多错误。有人可以帮助我理解它吗？非常感谢

public static String reverse_recursion(String str) {
    if (str == null)
        return null;
    else {
        String Arry[] = str.split(" ");
        int n = Arry.length - 1;
        System.out.println(Arry[n] + "");
        return reverse_recursion(Arry[n - 1]);
    }
}

public static void main(String[] args) {
    reverse_recursion("Cat Is Running");
}

此代码显示以下输出:

Running
Is
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -1

这段代码不打印(0)索引为什么？有人可以帮我解决这个错误吗

Answer 1

这个解决方案可能会有所帮助。注释非常详细地解释了代码。

public static String reverse_recursion(String str) {
    String[] arry = str.split(" ", 2); //Split into a maximum of 2 Strings

    if (arry.length > 1) { //If there is more than 1 word in arry
        //Return the reverse of the rest of the str (arry[1])           
        //and concatenate together with the first word (arry[0])
        return reverse_recursion(arry[1]) + " " + arry[0];
    }

    return arry[0]; //If less than or equal to 1 word, just return that word
}