CharArrayWriter append() method in Java with Examples

The append() method of CharArrayWriter class in Java is of three types:

1. The append(char) method of CharArrayWriter class in Java is used to append the specified character to the writer. This append() method appends one character at a time to the CharArrayWriter and returns this CharArrayWriter.
   Syntax:
   

   public CharArrayWriter append(char c)
   
   

   Specified By: This method is specified by the append() method of Appendable interface.
   Overrides: This method overrides the append() method of Writer class.
   Parameters: This method accepts one parameter c that represents the 16-bit character that is to be appended.
   Return value: This method returns CharArrayWriter after appending the character into it.
   Exceptions: This method does not throw any exception.
   Below program illustrates append(char) method in CharArrayWriter class in IO package:
   Program:
   

   Java

   // Java program to illustrate
   // CharArrayWriter append(char) method
   
   import java.io.*;
   
   public class GFG {
       public static void main(String[] args)
       {
   
           // Create charArrayWriter
           CharArrayWriter charArrayWriter
               = new CharArrayWriter();
   
           // Append the character
           charArrayWriter.append('G');
   
           charArrayWriter.append('E');
   
           charArrayWriter.append('E');
   
           charArrayWriter.append('K');
   
           charArrayWriter.append('S');
   
           // print the charArrayWriter
           System.out.println(
               charArrayWriter.toString());
       }
   }
   Output:

   GEEKS
   

2. The append(CharSequence) method of CharArrayWriter class in Java is used to append the specified character sequence to the writer. This append() method appends a character sequence at a time to the CharArrayWriter and returns this CharArrayWriter.
   Syntax:
   

   public CharArrayWriter append(CharSequence csq)
   

   Specified By: This method is specified by the append() method of Appendable interface.
   Overrides: This method overrides the append() method of Writer class.
   Parameters: This method accepts one parameter csq that represents the character sequence that is to be appended. If the character sequence is null then the 4 characters ‘null’ is appended to the CharArrayWriter.
   Return value: This method returns CharArrayWriter after appending the character sequence into it.
   Exceptions: This method does not throw any exception.
   Below program illustrates append(CharSequence) method in CharArrayWriter class in IO package:
   Program:
   

   Java

   // Java program to illustrate
   // CharArrayWriter append(CharSequence) method
   
   import java.io.*;
   
   public class GFG {
       public static void main(String[] args)
       {
   
           // Create charArrayWriter
           CharArrayWriter charArrayWriter
               = new CharArrayWriter();
   
           // Create character sequence
           CharSequence csq1 = "GEEKS";
   
           CharSequence csq2 = "FOR";
   
           // Append character sequences
           // to the charArrayWriter
           charArrayWriter.append(csq1);
   
           charArrayWriter.append(csq2);
   
           charArrayWriter.append(csq1);
   
           // print the charArrayWriter
           System.out.println(
               charArrayWriter.toString());
       }
   }
   Output:

   GEEKSFORGEEKS
   

3. The append(CharSequence, int, int) method of CharArrayWriter class in Java is used to append the subsequence of a specified character sequence to the writer. This append() method appends a portion of character sequence to the CharArrayWriter and returns this CharArrayWriter.
   Syntax:
   

   public CharArrayWriter append(CharSequence csq, 
                                 int start, 
                                 int end)
   
   

   Specified By: This method is specified by the append() method of Appendable interface.
   Overrides: This method overrides the append() method of Writer class.
   Parameters: This method accepts three parameters: 
   

   • csq – It represents the character sequence whose subsequence is to be appended.
   • start – It represents the starting index for the subsequence.
   • end – It represents the index of character following the end for the subsequence.

   Return value: This method returns CharArrayWriter after appending the subsequence of the given character sequence into it.
   Exceptions: This method throws IndexOutOfBoundsException if the start or the end are negative or start is greater than end or end is greater than the length of given character sequence.
   Below program illustrates append(CharSequence, int, int) method in CharArrayWriter class in IO package:
   Program:
   

   Java

   // Java program to illustrate
   // CharArrayWriter
   // append(CharSequence, int, int) method
   
   import java.io.*;
   
   public class GFG {
       public static void main(String[] args)
       {
   
           // Create charArrayWriter
           CharArrayWriter charArrayWriter
               = new CharArrayWriter();
   
           // Create character sequence
           CharSequence csq = "GEEKSFORGEEKS";
   
           // Append subsequence of character
           // sequence to the charArrayWriter
           charArrayWriter.append(csq, 8, 13);
   
           // print the charArrayWriter
           System.out.println(
               charArrayWriter.toString());
       }
   }
   Output:

   GEEKS
   

References:
1. https://docs.oracle.com/javase/10/docs/api/java/io/CharArrayWriter.html#append(char)
2. https://docs.oracle.com/javase/10/docs/api/java/io/CharArrayWriter.html#append(java.lang.CharSequence)
3. https://docs.oracle.com/javase/10/docs/api/java/io/CharArrayWriter.html#append(java.lang.CharSequence, int, int)