在Java中将一个字符串插入另一个字符串

给定一个字符串，任务是在给定字符串之间插入另一个字符串，位于Java中的特定索引处。

例子：

输入： originalString = "GeeksGeeks", stringToBeInserted = "For", index = 4输出： "GeeksForGeeks" 输入： originalString = “计算机门户”，stringToBeInserted = “科学”，索引 = 8输出： “计算机科学门户”

执行此操作的各种方法如下：

1. 不使用任何预定义的方法

   方法：

   1. 获取字符串和索引。
   2. 创建一个新字符串
   3. 遍历字符串直到指定索引并将其复制到新字符串中。
   4. 将要插入的字符串复制到这个新字符串中
   5. 将第一个字符串的剩余字符复制到新字符串中
   6. 返回/打印新字符串

   下面是上述方法的实现：

   程序：

   // Java program to insert a string into another string
   // without using any pre-defined method
     
   import java.lang.*;
     
   class GFG {
     
       // Function to insert string
       public static String insertString(
           String originalString,
           String stringToBeInserted,
           int index)
       {
     
           // Create a new string
           String newString = new String();
     
           for (int i = 0; i < originalString.length(); i++) {
     
               // Insert the original string character
               // into the new string
               newString += originalString.charAt(i);
     
               if (i == index) {
     
                   // Insert the string to be inserted
                   // into the new string
                   newString += stringToBeInserted;
               }
           }
     
           // return the modified String
           return newString;
       }
     
       // Driver code
       public static void main(String[] args)
       {
     
           // Get the Strings
           String originalString = "GeeksGeeks";
           String stringToBeInserted = "For";
           int index = 4;
     
           System.out.println("Original String: "
                              + originalString);
           System.out.println("String to be inserted: "
                              + stringToBeInserted);
           System.out.println("String to be inserted at index: "
                              + index);
     
           // Insert the String
           System.out.println("Modified String: "
                              + insertString(originalString,
                                             stringToBeInserted,
                                             index));
       }
   }
   

   输出：

   Original String: GeeksGeeks
   String to be inserted: For
   String to be inserted at index: 4
   Modified String: GeeksForGeeks
   

2. 使用 String.substring() 方法

   方法：

   1. 获取字符串和索引。
   2. 创建一个新字符串
   3. 使用 substring(0, index+1) 方法插入从 0 到指定 (index + 1) 的子字符串。然后将要插入的字符串插入到字符串中。然后使用 substring(index+1) 方法将原始字符串的剩余部分插入到新字符串中。
   4. 返回/打印新字符串

   下面是上述方法的实现：

   程序：

   // Java program to insert a string into another string
   // without using any pre-defined method
     
   import java.lang.*;
     
   class GFG {
     
       // Function to insert string
       public static String insertString(
           String originalString,
           String stringToBeInserted,
           int index)
       {
     
           // Create a new string
           String newString = originalString.substring(0, index + 1)
                              + stringToBeInserted
                              + originalString.substring(index + 1);
     
           // return the modified String
           return newString;
       }
     
       // Driver code
       public static void main(String[] args)
       {
     
           // Get the Strings
           String originalString = "GeeksGeeks";
           String stringToBeInserted = "For";
           int index = 4;
     
           System.out.println("Original String: "
                              + originalString);
           System.out.println("String to be inserted: "
                              + stringToBeInserted);
           System.out.println("String to be inserted at index: "
                              + index);
     
           // Insert the String
           System.out.println("Modified String: "
                              + insertString(originalString,
                                             stringToBeInserted,
                                             index));
       }
   }
   

   输出：

   Original String: GeeksGeeks
   String to be inserted: For
   String to be inserted at index: 4
   Modified String: GeeksForGeeks
   

3. 使用 StringBuffer.insert() 方法

   方法：

   1. 获取字符串和索引。
   2. 创建一个新的字符串缓冲区
   3. 使用 StringBuffer.insert() 方法将 stringToBeInserted 插入原始字符串。
   4. 使用 StringBuffer.toString() 方法从 StringBuffer 返回/打印字符串。

   下面是上述方法的实现：

   程序：

   // Java program to insert a string into another string
   // without using any pre-defined method
     
   import java.lang.*;
     
   class GFG {
     
       // Function to insert string
       public static String insertString(
           String originalString,
           String stringToBeInserted,
           int index)
       {
     
           // Create a new StringBuffer
           StringBuffer newString
               = new StringBuffer(originalString);
     
           // Insert the strings to be inserted
           // using insert() method
           newString.insert(index + 1, stringToBeInserted);
     
           // return the modified String
           return newString.toString();
       }
     
       // Driver code
       public static void main(String[] args)
       {
     
           // Get the Strings
           String originalString = "GeeksGeeks";
           String stringToBeInserted = "For";
           int index = 4;
     
           System.out.println("Original String: "
                              + originalString);
           System.out.println("String to be inserted: "
                              + stringToBeInserted);
           System.out.println("String to be inserted at index: "
                              + index);
     
           // Insert the String
           System.out.println("Modified String: "
                              + insertString(originalString,
                                             stringToBeInserted,
                                             index));
       }
   }
   

   输出：

   Original String: GeeksGeeks
   String to be inserted: For
   String to be inserted at index: 4
   Modified String: GeeksForGeeks