logo

JAVA Tutorial

Java Object Oriented

Advanced Java Tutorial

Java Other Topics

String Buffer And String Builder Classes

Show

The StringBuffer and StringBuilder classes are utilized while there is a requirement to make several alterations to Strings of values.

Contrasting Strings, values of type StringBuffer and String designer can be altered repeatedly with no leaving after several new unused objects.

The StringBuilder class was set up as of Java 5 and the major divergence between the StringBuffer and StringBuilder is that StringBuilder techniques are not thread-safe (not synchronized).

It is optional to use StringBuilder when possible since it is faster than StringBuffer. Yet, if thread security is essential, the best alternative is StringBuffer objects.

Example

public class Test {

   public static void main(String args[]) {
      StringBuffer sBuffer = new StringBuffer("test");
      sBuffer.append(" String Buffer");
      System.out.println(sBuffer);  
   }
}

This will produce the following result −

Output

test String Buffer

StringBuffer Methods

Here is the list of important methods supported by the StringBuffer class −

Sr.No.Methods & Description
1public StringBuffer append(String s)

Updates the value of the object that invoked the method. The method takes boolean, char, int, long, Strings, etc.

2public StringBuffer reverse()

The method reverses the value of the StringBuffer object that invoked the method.

3public delete(int start, int end)

Deletes the string starting from the start index until the end index.

4public insert(int offset, int i)

This method inserts a string s at the position mentioned by the offset.

5replace(int start, int end, String str)

This method replaces the characters in a substring of this StringBuffer with characters in the specified String.

Here is the list of other methods (except set methods) which are very similar to the String class −

Sr.No.Method & Description
1

int capacity()

Returns the current capacity of the String buffer.

2

char charAt(int index)

The specified character of the sequence currently represented by the string buffer, as indicated by the index argument, is returned.

3

void ensureCapacity(int minimumCapacity)

Ensures that the capacity of the buffer is at least equal to the specified minimum.

4

void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)

Characters are copied from this string buffer into the destination character array DST.

5

int indexOf(String str)

Returns the index within this string of the first occurrence of the specified substring.

6

int indexOf(String str, int fromIndex)

Returns the index within this string of the first occurrence of the specified substring, starting at the specified index.

7

int lastIndexOf(String str)

Returns the index within this string of the rightmost occurrence of the specified substring.

8

int lastIndexOf(String str, int fromIndex)

Returns the index within this string of the last occurrence of the specified substring.

9

int length()

Returns the length (character count) of this string buffer.

10

void setCharAt(int index, char ch)

The character at the specified index of this string buffer is set to ch.

11

void setLength(int newLength)

Sets the length of this String buffer.

12

CharSequence subSequence(int start, int end)

Returns a new character sequence that is a subsequence of this sequence.

13

String substring(int start)

Returns a new String that contains a subsequence of characters currently contained in this StringBuffer. The substring begins at the specified index and extends to the end of the StringBuffer.

14

String substring(int start, int end)

Returns a new String that contains a subsequence of characters currently contained in this StringBuffer.

15

String toString()

Converts to a string representing the data in this string buffer.

Here at Intellinuts, we have created a complete Java tutorial for Beginners to get started in Java.