Java SE|字符串部分反转

//没有设置限制条件（a、b的值要求等等），易报错
public class StringTest2 {
    public static String restring(String Str,int a,int b){
        int j = 0,m = 0,n =0;
        char[] newChar = Str.toCharArray();
        char[] reNewChar = new char[b-a+1];
        for (int i = b; i >= a ; i--) {
            reNewChar[j++] = newChar[i];
        }
        char[] firstChar = new char[a];
        for (int i = 0; i < a; i++) {
            firstChar[m++] = newChar[i];
        }
        char[] lastChar = new char[newChar.length-b+1];
        for (int i = b + 1; i < newChar.length ; i++) {
            lastChar[n++] = newChar[i];
        }
        String newStr = new String(firstChar) + new String(reNewChar) + new String(lastChar);
        return newStr;
    }

    public static void main(String[] args) {
        String a = StringTest2.restring("01234567",3,5);
        System.out.println(a);
    }
}