StringWriter in java

A character stream that collects its output in a string buffer, which can then be used to construct a string.

import java.io.StringWriter;

public class StringWriterEx {
 public static void main(String args[]){
  StringWriter writer = new StringWriter();
 
  writer.write("first line ");
  System.out.println(writer);
  
  writer.write("Second line");
  System.out.println(writer);
   
 }
}

Output

first line 
first line Second line

StringWriter internally use StringBuffer, to store data. You can get the buffer using “getBuffer” method of StringWriter. Whatever the changes you do to the buffer is reflected to writer.

import java.io.StringWriter;

public class StringWriterEx {
 public static void main(String args[]){
  StringWriter writer = new StringWriter();
 
  StringBuffer buffer = writer.getBuffer();
  
  buffer.append("first line");
  System.out.println(writer);
  
  buffer.append("Second line");
  System.out.println(writer);  
   
 }
}

Output

first line
first lineSecond line