Java StringBuffer Example

In this post we present to you Java StringBuffer class usage example. When you need to do a lot of modifications on a String object, like concatenating it with another String, removing it’s fragment and so on, the best choice is to use Java StringBuffer class.

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ITCuties – Java StringBuffer

Remember that + operator that modifies the String object creates another String object as a result of the join operation. This doesn’t happen when you use the StringBuffer’s append method, so as the result your program uses less memory. StringBuffer class can be used not only for joining strings. Here is the example:

Java StringBuffer – example

package com.itcuties.java;

/**
* Java StringBuffer example.
*
* @author itcuties
*
*/
public class StringBufferExample {

   public static void main(String[] args) {
       
       StringBuffer sb = new StringBuffer("Sample StringBuffer's value");
       
       // sb.toString() is called here
       System.out.println("original: " + sb);
       
       // length() method call returns the actual length of the string held in the StringBuffer
       // capacity() method call returns StringBuffer object's capacity. This is number of characters that StringBuffer object can currently hold.
       // Capacity of the StringBuffer object is managed automatically.
       System.out.println("length(): " + sb.length() + ", capacity(): " + sb.capacity());
       
       // charAt() method call returns the character that is hold at the given index of the StringBuffer object
       System.out.println("charAt(): " + sb.charAt(5)); //'e' character - [0]S [1]a [2]m [3]p [4]l [5]e [6] [7]S [8] [9]t [10]r [11]i [12]n [13]g...
       
       // codePointAt() method call returns the code point value (unicode code) of the character at the given index
       System.out.println("codePointAt(): " + sb.codePointAt(5)); // 'e' sign unicode code
       
       // append() method call joins StringBuffer value with the String value passed as the argument
       System.out.println("append(): " + sb.append(" by itcuties"));
       
       // insert() method call inserts the string representation of the object passed as the argument at the given index
       System.out.println("insert(): " + sb.insert(7, "[INSERT THIS] "));
       
       // indexOf() method call returns the index within this string of the first occurrence of the String passed as the argument.
       System.out.println("indexOf():" + sb.indexOf("[INSERT THIS]"));
       
       // delete() method call removes the characters from the index 7 up to index 20
       System.out.println("delete(): " + sb.delete(7, 7+ "[INSERT THIS] ".length()));
       
       // substring() method call returns a new String that contains a subsequence of characters currently contained in this sequence.
       // In this example the code returns the substring from the index 31 up to index 38
       System.out.println("substing(): " + sb.substring(31,39));

       // reverse() method call results in reversing the characters order of the string held in the StringBuffer object
       System.out.println("reverse(): " + sb.reverse());
       
   }
}

Output:

original: Sample StringBuffer's value

length(): 27, capacity(): 43

charAt(): e

codePointAt(): 101

append(): Sample StringBuffer's value by itcuties

insert(): Sample [INSERT THIS] StringBuffer's value by itcuties

indexOf():7

delete(): Sample StringBuffer's value by itcuties

substing(): itcuties

reverse(): seitucti yb eulav s'reffuBgnirtS elpmaS

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Download this sample code here.

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This code is available on our GitHub repository as well.

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