返回由字符串奇数索引位置的字符组成的字符串

huangapple
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英文:

Returning a string made by odd index number of the string

问题

  1. public class MeWhileLoop
  2. {
  3.     
  4.     public int a, b;
  5.     public String str;
  7.     public String OddNumChar(){
  8.         
  9.         int index = 0;
  10.         str = "Poland";
  11.         String result = "";  // Initialize an empty string to store the result
  12.         
  13.         while(index < str.length()){
  14.             if(index % 2 != 0){  // Check if the index is odd
  15.                 result += str.substring(index, index+1);  // Append the odd-indexed character to the result
  16.             }
  17.             index++;
  18.         }
  19.         
  20.         return result;  // Return the string containing odd-indexed characters
  21.     }
  23. }
英文:

The Return type is a String and no Input parameters. I have to go through the instance variable called str and return a string that is put together by odd index number of the string.

i forgot to mention that it has to be a while loop

Example: str = "Poland"

  1.      then the method should return &quot;oad&quot; because P is an even number, o is odd, l is even, a is odd, n is even, d is odd.

I so far have come up with this

  1. public class MeWhileLoop
  2. {
  3.     
  4.     public int a, b;
  5.     public String str;
  7.     public String OddNumChar(){
  8.         
  9.         int index = 0;
  10.         str = &quot;Poland&quot;;
  11.         while(index &lt; str.length()){
  12.             
  13.             System.out.println(str.substring(index, index+1));
  14.             index++;
  15.             
  16.         }
  17.         System.out.println();
  18.         return str;
  19.     }
  21. }

I'm just stuck because the index+1 won't take out the odd letters or any letter at all and I have no clue why.

答案1

得分: 3

以下是翻译好的内容：

第一段代码：

  1. 如何考虑：
  3.     String res = "";
  5.     // 从第二个字符开始，然后每次增加2
  6.     for (int i = 1; i < str.length(); i += 2) {
  7.         res += str.charAt(i);
  8.     }
  10.     return res;

第二段代码：

  1. 对于更大的字符串，这可能具有更好的性能：
  3.     StringBuilder sb = new StringBuilder(str.length() / 2);
  5.     for (int i = 1; i < str.length(); i += 2) {
  6.         sb.append(str.charAt(i));
  7.     }
  9.     return sb.toString();

第三段代码：

  1. 如果出于某种原因确实需要使用 while 循环：
  3.     String res = "";
  5.     int i = 1;
  6.     while (i < str.length()) {
  7.         res += str.charAt(i);
  8.         i += 2;
  9.     }
  11.     return res;
英文:

How about:

  1. String res = &quot;&quot;;
  3. // start at second character and then increment by 2
  4. for (int i = 1; i &lt; str.length(); i += 2) {
  5.     res += str.charAt(i);
  6. }
  8. return res;

This might have better performance for larger strings:

  1. StringBuilder sb = new StringBuilder(str.length() / 2);
  3. for (int i = 1; i &lt; str.length(); i += 2) {
  4.     sb.append(str.charAt(i));
  5. }
  7. return sb.toString();

If you really need while loop for some reason:

  1. String res = &quot;&quot;;
  3. int i = 1;
  4. while (i &lt; str.length()) {
  5.     res += str.charAt(i);
  6.     i += 2;
  7. }
  9. return res;

huangapple
  • 本文由 发表于 2020年9月26日 04:30:33
  • 转载请务必保留本文链接：https://go.coder-hub.com/64071001.html
  • indexing
  • java
  • string
  • substring
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