在Java中交换字符串中的字符对

给定字符串str ，任务是编写一个Java程序来交换字符串的字符对。如果字符串包含奇数个字符，则最后一个字符保持原样。

例子：

Input: str = “Java”

Output: aJva

Explanation: The given string contains even number of characters. Therefore, we swap every pair of characters.

Input: str = “GeeksForGeeks”

Output: eGkeFsroeGkes

Explanation: The given string contains odd number of characters. Therefore, we swap every pair of characters and last character remains as it is.

1. 使用String.toCharArray()方法

1. 获取字符串交换一对字符。
2. 检查字符串是否为空或空，然后返回字符串。
3. 将给定的字符串转换为字符数组。
4. 遍历字符数组并交换字符。
5. 现在，打印结果。

Java

// Java program to swap pair
// of characters of a string
  
class GFG {
  
    // Function to swap pair of
    // characters of a string
    public static String swapPair(String str)
    {
  
        // Checking if string is null
        // or empty then return str
        if (str == null || str.isEmpty())
            return str;
  
        // Converting the given string
        // into a character array
        char[] ch = str.toCharArray();
  
        // Traverse the character array
        for (int i = 0; i < ch.length - 1; i += 2) {
  
            // Swapping the characters
            char temp = ch[i];
            ch[i] = ch[i + 1];
            ch[i + 1] = temp;
        }
  
        // Converting the result into a
        // string and return
        return new String(ch);
    }
  
    // Driver Code
    public static void main(String args[])
    {
  
        // Given String str
        String str = "GeeksForGeeks";
  
        // Print the result
        System.out.println(swapPair(str));
    }
}

输出

eGkeFsroeGkes

2. 使用StringBuffer.append()方法

1. 获取字符串交换一对字符。
2. 检查字符串是否为空或空，然后返回字符串。
3. 使用作为参数传递的字符串长度创建一个StringBuffer对象。
4. 遍历字符串并以相反的顺序将字符追加到StringBuffer对象中。
5. 检查字符串是否包含奇数个字符，然后将最后一个字符附加到StringBuffer对象中。
6. 现在，打印结果。

Java

// Java program to swap pair
// of characters of a string
  
class GFG {
  
    // Function to swap pair of
    // characters of a string
    public static String swapPairs(String str)
    {
  
        // Checking if string is null
        // or empty then return str
        if (str == null || str.isEmpty())
            return str;
  
        int len = str.length();
  
        // Creating a StringBuffer object with
        // length of the string passed as a parameter
        StringBuffer sb = new StringBuffer(len);
  
        // Traverse the string and append
        // the character in the StringBuffer
        // object in reverse order
        for (int i = 0; i < len - 1; i += 2) {
            sb.append(str.charAt(i + 1));
            sb.append(str.charAt(i));
        }
  
        // Checking if the string has
        // odd number of characters
        // then append the last character
        // into StringBuffer object
        if (len % 2 != 0) {
            sb.append(str.charAt(len - 1));
        }
  
        // Converting the StringBuffer
        // into the string and return
        return sb.toString();
    }
  
    // Driver Code
    public static void main(String args[])
    {
  
        // Given String str
        String str = "GeeksForGeeks";
  
        // Print the result
        System.out.println(swapPairs(str));
    }
}

输出

eGkeFsroeGkes