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StringBuffer Class in Java

StringBuffer Class in Java

`StringBuffer` is a class in Java that represents a mutable sequence of characters. Unlike the `String` class, which is immutable, a `StringBuffer` allows for the modification of its content without creating a new object. This makes it more efficient for situations where frequent modifications to a sequence of characters are required.


Key Features:


1. Mutability:

   - `StringBuffer` objects are mutable, meaning the content of a `StringBuffer` instance can be modified after its creation.


2. Synchronization:

   - `StringBuffer` is synchronized, making it thread-safe. This ensures that multiple threads can safely access and modify a `StringBuffer` object without interference.


3. Performance Considerations:

   - While `StringBuffer` provides mutability, it might have performance overhead due to synchronization. If thread safety is not required, the non-synchronized class `StringBuilder` should be considered for better performance.


Common Methods:


Here are some commonly used methods of the `StringBuffer` class:


1. Constructor:


- `StringBuffer()`

  - Creates an empty `StringBuffer` with the default initial capacity (16 characters).


  • StringBuffer buffer = new StringBuffer();


2. Appending Content:


- `append(String str)`

  - Appends the specified string to the end of the `StringBuffer`.


buffer.append("Hello");

buffer.append(" World");


3. Inserting Content:


- `insert(int offset, String str)`

  - Inserts the specified string at the specified offset.


  • buffer.insert(5, " Java");


 4. Deleting Content:


- `delete(int start, int end)`

  - Deletes the characters between the specified `start` (inclusive) and `end` (exclusive) indices.


buffer.delete(6, 11);



5. Reversing Content:


- `reverse()`

  - Reverses the characters in the `StringBuffer`.

  • buffer.reverse();


6. Capacity Management:

- `capacity()`

  - Returns the current capacity of the `StringBuffer`.

  • int capacity = buffer.capacity();


- `ensureCapacity(int minCapacity)`

  - Ensures that the capacity of the `StringBuffer` is at least equal to the specified minimum capacity.

  • buffer.ensureCapacity(50);


7. Converting to String:

- `toString()`

  - Converts the `StringBuffer` to a `String`.


  • String result = buffer.toString();



 Example Usage:



// Creating a StringBuffer

StringBuffer buffer = new StringBuffer();


// Appending content

buffer.append("Hello");

buffer.append(" World");


// Inserting content

buffer.insert(5, " Java");


// Deleting content

buffer.delete(6, 11);


// Reversing content

buffer.reverse();


// Converting to String

String result = buffer.toString();



The `StringBuffer` class provides a flexible and thread-safe way to work with mutable character sequences in Java. If synchronization is not required, consider using the `StringBuilder` class for potentially better performance.

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