Question

我正在尝试创建一个方法，将位置为p的char更改为字符串“s”中的char“c”。它需要是递归的，除了charAt（）和lenght（）之外，我不允许使用String类中的任何其他方法。但是，现在，它只返回null。请帮忙。

import java.util.*;

public class Main {
    public static void main(String[] args) {
       //Test
       String S = new String("augusto");
       Word W = new Word(S);
       System.out.println(W.changeChar(S, 'x', 3));
   }
}

class Word {

    public static String s;
    static int counter, length;
    static char [] arrayChar = new char[length];

    Word(String x){
        this.s = x;
        this.length = x.length();
        this.arrayChar = new char[length];
        this.counter = 0;
    }

//This Method changes to char "c" from a string "s", given the position "p"
    public static String changeChar(String s, char c, int p){
        if(counter == (s.length()-1)){
            String r = new String(arrayChar);
            return r;
        } else if(counter == p){
            arrayChar[counter] = c;
            counter = counter + 1;
            changeChar(s, c, p);
        } else { 
            arrayChar[counter] = s.charAt(counter);
            counter = counter + 1;
            changeChar(s, c, p);
        }
        return null;
    }
}

Answer 1

试试这段代码：

public class Main {
    public static void main(String[] args) {
       //Test

       System.out.println(new Word("augusto").changeChar('x', 0));
   }
}

class Word {

    private int mLength;
    private char [] arrayChar;

    Word(String x){
        this.mLength = x.length();
        this.arrayChar = x.toCharArray();
    }

    public String changeChar(char c, int position) {
        return changeChar(c, position, 0);
    }

//This Method changes to char "c" from a string "s", given the position "p"
    private String changeChar(char c, int position, int currentIndex){
        if (currentIndex == mLength - 1) {
            return new String(arrayChar);
        } else if (currentIndex == position){
            arrayChar[currentIndex] = c;
            return new String(arrayChar);
        } else {
            return changeChar(c, position, currentIndex + 1);
        }
    }
}

从字符串中更改字符的递归方法

1 个答案: