what is the use of StringBuffer?

Answer Posted / koti reddy

A string buffer implements a mutable sequence of characters. A string buffer is like a String, but can be modified. At any point in time it contains some particular sequence of characters, but the length and content of the sequence can be changed through certain method calls.

String buffers are safe for use by multiple threads. The methods are synchronized where necessary so that all the operations on any particular instance behave as if they occur in some serial order that is consistent with the order of the method calls made by each of the individual threads involved.

String buffers are used by the compiler to implement the binary string concatenation operator +. For example, the code:

x = "a" + 4 + "c"

is compiled to the equivalent of:

x = new StringBuffer().append("a").append(4).append("c")
.toString()

which creates a new string buffer (initially empty), appends the string representation of each operand to the string buffer in turn, and then converts the contents of the string buffer to a string. Overall, this avoids creating many temporary strings.
The principal operations on a StringBuffer are the append and insert methods, which are overloaded so as to accept data of any type. Each effectively converts a given datum to a string and then appends or inserts the characters of that string to the string buffer. The append method always adds these characters at the end of the buffer; the insert method adds the characters at a specified point.

For example, if z refers to a string buffer object whose current contents are "start", then the method call z.append("le") would cause the string buffer to contain "startle", whereas z.insert(4, "le") would alter the string buffer to contain "starlet".

In general, if sb refers to an instance of a StringBuffer, then sb.append(x) has the same effect as sb.insert(sb.length(), x).

Every string buffer has a capacity. As long as the length of the character sequence contained in the string buffer does not exceed the capacity, it is not necessary to allocate a new internal buffer array. If the internal buffer overflows, it is automatically made larger.

Is This Answer Correct ?    6 Yes 0 No



Post New Answer       View All Answers


Please Help Members By Posting Answers For Below Questions

If an application has multiple classes in it, is it okay to have a main method in more than one class?

773


Can we write any code after throw statement?

835


what is comparable and comparator interface?

777


What is null mean in java?

859


What do you understand by soft reference?

825


How does hashset work in java?

823


Is java a security risk?

810


What is constructor and virtual function? Can we call a virtual function in a constructor?

912


Where pragma is used?

835


What about interrupt() method of thread class ?

854


Explain exception chaining in java?

849


how to prepare for IT Officers Interview in Banks

1721


Is zero a positive integer?

783


When to use runnable interface vs thread class in java?

767


What is constructor chaining in java?

835