Java StringBuffer class

StringBuffer is a mutable sequence of characters. It is like a String bu the contents of the StringBuffer can be modified after creation.

Problems in the String class

• String characters cannot be changed after assigning
• String is read only and immutable (fixed)
• String is slower to concatenate

StringBuffer Advantages

• It is possible to insert characters and substrings in the start,middle,end of string
• It is mutable sequence of characters. We can easily modify the String.
• It increases the storing of capacity of characters automatically when more contents are added.
• It is faster than string while performing string concatenation.

StringBuffer Syntax

StringBuffer strbuffer = new StringBuffer("Your String");

Example

class SBuffer
{
    public static void main(String args[])
    {  
        StringBuffer mystring = new StringBuffer("AndroidBerry");
        System.out.println(mystring);
    }
}

Output

StringBuffer Capacity

The capacity() method is used to get current capacity of the stringBuffer object. The default capacity of StringBuffer object is 16 characters. In above example While printing mystring.capacity() we get output as 28 (16 + 12). 12 is length of mystring.length() of 'AndroidBerry'

StringBuffer Constructors

There are 3 different types of StringBuffer Constructors. 1 default and other 2 are parameterized.

1.StringBuffer ()

This constructor creates an empty string of initial capacity of 16 characters

Example

StringBuffer sb = new StringBuffer();

2.StringBuffer (int capacity)

This constructor creates an empty string with specified initial capacity of object. The value should not be less than 0

Example

StringBuffer sb = new StringBuffer(20);

3.StringBuffer(String stringContent)

This constructor creates an object having stringContent as argument. The capacity of this type of object is 16 + stringContent.length()

Example

StringBuffer sb = new StringBuffer("AndroidBerry");

Methods of StringBuffer class

All the methods are stored in the StringBuffer class of java.lang.StringBuffer.method()

Assume our StringBuffer objects are as shown below.

StringBuffer sb = new StringBuffer ("ABerry")

StringBuffer sb2 = new StringBuffer ("Android Berry")

StringBuffer sb3 = new StringBuffer ("Test")
sb3.append(123);