用 Java 将一个字符串插入到另一个字符串中

原文:https://www . geesforgeks . org/insert-a-string-in-other-string-in-Java/

给定一个字符串，任务是在 Java 中特定的指定索引处的给定字符串之间插入另一个字符串。

示例:

Input: originalString = "GeeksGeeks", 
              stringToBeInserted = "For", 
              index = 4
Output: "GeeksForGeeks"

Input: originalString = "Computer Portal", 
              stringToBeInserted = "Science ", 
              index = 8
Output: "Computer Science Portal"

实现这一点的各种方法如下:

1. Without using any pre-defined method

   进场:

   1. 获取字符串和索引。
   2. 创建新字符串
   3. 遍历字符串直到指定的索引，并将其复制到新的字符串中。
   4. 复制要插入到新字符串中的字符串
   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 // 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));     } } ```

   Output:

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

   ```

2. Using String.substring() method

   进场:

   1. 获取字符串和索引。
   2. 创建新字符串
   3. 使用 substring(0，index + 1)方法将子字符串从 0 插入到指定的(index+1)中。然后插入要插入到字符串中的字符串。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 // 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));     } } ```

   Output:

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

   ```

3. Using StringBuffer.insert() method

   进场:

   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()方法将字符串插入到原始字符串中。
   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 // 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));     } } ```

   Output:

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

   ```

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