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StringBuffer append() Method in Java with Examples

Last Updated : 11 Jul, 2025
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Pre-requisite: StringBuffer class in Java The java.lang.StringBuffer.append() method is used to append the string representation of some argument to the sequence. There are 13 ways/forms in which the append() method can be used:
  1. StringBuffer append(boolean a) :The java.lang.StringBuffer.append(boolean a) is an inbuilt method in Java which is used to append the string representation of the boolean argument to a given sequence. Syntax : 
    public StringBuffer append(boolean a)
    Parameter : This method accepts a single parameter a of boolean type and refers to the Boolean value to be appended. Return Value : The method returns a reference to this object. Examples: 
    Input: 
string_buffer = "I love my Country" 
boolean a = true

Output: I love my Country true
    Below program illustrates the java.lang.StringBuffer.append() method: java 
    // Java program to illustrate the
// StringBuffer append(boolean a)
import java.lang.*;

public class Geeks {

    public static void main(String[] args)
    {

        StringBuffer sbf1 = new StringBuffer("We are geeks and its really ");
        System.out.println("Input: " + sbf1);

        // Appending the boolean value
        sbf1.append(true);
        System.out.println("Output: " + sbf1);

        System.out.println();

        StringBuffer sbf2 = new StringBuffer("We are lost - ");
        System.out.println("Input: " + sbf2);

        // Appending the boolean value
        sbf2.append(false);
        System.out.println("Output: " + sbf2);
    }
}
    Output: 
    Input: We are geeks and its really 
Output: We are geeks and its really true

Input: We are lost - 
Output: We are lost - false
  2. java.lang.StringBuffer.append(char a) : This is an inbuilt method that appends the string representation of the char argument to the given sequence. The char argument is appended to the contents of this StringBuffer sequence. Syntax : 
    public StringBuffer append(char a)
    Parameter : The method accepts a single parameter a which is the Char value whose string representation is to be appended. Return Value: The method returns a string object after the append operation is performed. Examples : 
    Input :
StringBuffer = I love my Country 
char a = A

Output: I love my Country A
    Below programs illustrate the java.lang.StringBuffer.append(char a) method. java 
    // Java program to illustrate the
// java.lang.StringBuffer.append(char a)
import java.lang.*;

public class Geeks {

    public static void main(String[] args)
    {
        System.out.println("We are geeks and its really ");
        StringBuffer sbf = new StringBuffer("We are geeks and its");

        /* Here it appends the char argument as
         string to the string buffer */
        sbf.append('M');
        System.out.println("Result after appending = " + sbf);

        System.out.println("We are lost -");
        sbf = new StringBuffer("We are lost -");

        /* Here it appends the char argument as
         string to the string buffer */
        sbf.append('&');
        System.out.println("Result after appending = " + sbf);
    }
}
    Output: 
    We are geeks and its really 
Result after appending = We are geeks and itsM
We are lost -
Result after appending = We are lost -&
  3. StringBuffer append(char[] astr): The java.lang.StringBuffer.append(char[] astr) is the inbuilt method which appends the string representation of the char array argument to this StringBuffer sequence. Syntax : 
    public StringBuffer append(char[] astr)
    Parameter : The method accepts a single parameter astr which are the Char sequence whose string representation is to be appended. Return Value: The method returns a string object after the append operation is performed. Examples: 
    Input :
StringBuffer  = I love my Country   
char[] astr = 'I', 'N', 'D', 'I', 'A'

Output: I love my Country INDIA
    Below program illustrates the java.lang.StringBuffer.append(char[] astr) method: java 
    // Java program to illustrate the
// java.lang.StringBuffer.append(<em>char[] astr</em>)
import java.lang.*;

public class Geeks {

    public static void main(String[] args)
    {

        System.out.println("We are geeks and its really ");
        StringBuffer sbf = new StringBuffer("We are geeks and its ");

        // Char array
        char[] astr = new char[] { 'G', 'E', 'E', 'k', 'S' };

        /* Here it appends string representation of char array 
        argument to this string buffer */
        sbf.append(astr);
        System.out.println("Result after appending = " + sbf);

        System.out.println("We are lost -");
        sbf = new StringBuffer("We are lost -");

        // Char array
        astr = new char[] { 'a', 'b', 'c', 'd' };

        /* Here it appends string representation of char array argument to
        argument to this string buffer */
        sbf.append(astr);
        System.out.println("Result after appending = " + sbf);
    }
}
    Output: 
    We are geeks and its really 
Result after appending = We are geeks and its GEEkS
We are lost -
Result after appending = We are lost -abcd
  4. StringBuffer append(char[] cstr, int iset, int ilength) : This method appends the string representation of a subarray of the char array argument to this sequence. The Characters of the char array cstr, starting at index iset, are appended, in order, to the contents of this sequence. The length of this sequence increases by the value of ilength. Syntax : 
    public StringBuffer append(char[] cstr, int iset, int ilength)
    Parameter : This method accepts three parameters:
    • cstr - This refers to the Char sequence.
    • iset - This refers to the index of the first char to append.
    • ilength - This refers to the number of chars to append.
    Return Value: The method returns a string object after the append operation is performed. Below program illustrates the java.lang.StringBuffer.append(char[] cstr, int iset, int ilength) method. java 
    // Java program to illustrate the
// java.lang.StringBuffer append(char[] cstr, int iset, int length)
import java.lang.*;

public class Geeks {

    public static void main(String[] args)
    {

        StringBuffer sb = new StringBuffer("Geeks");
        System.out.println(" String buffer  before = " + sb);

        char[] cstr = new char[] { 'f', 'o', 'r', 'G', 'e', 'e', 'k', 's',
                                   'b', 'e', 'a', 'g', 'e', 'e', 'k' };

        /* appends the string representation of char array argument to this
      string buffer with offset initially at index 0 and length as 8 */
        sb.append(cstr, 0, 8);

        // Print the string buffer after appending
        System.out.println("After appending string buffer = " + sb);
    }
}
    Output: 
    String buffer  before = Geeks
After appending string buffer = GeeksforGeeks
  5. StringBuffer append(double a) : This method simply appends the string representation of the double argument to this StringBuffer sequence. Syntax : 
    public StringBuffer append(double a)
    Parameter: The method accepts a single parameter a which refers to the decimal value whose string representation is to be appended. Return Value: The method returns a string object after the append operation is performed. Examples : 
    Input :
StringBuffer = I love my Country
Double a = 54.82
Output: I love my Country 54.82
    Below program illustrates the java.lang.StringBuffer.append() method. java 
    // Java program to illustrate the
// java.lang.StringBuffer.append()
import java.lang.*;

public class Geeks {

    public static void main(String[] args)
    {

        System.out.println("We are geeks and its really ");
        StringBuffer sbf = new StringBuffer("We are geeks and its ");
        // char array
        Double astr = new Double(636.47);

        /*Here it appends string representation of Double argument to 
         this string buffer*/
        sbf.append(astr);
        System.out.println("Result after appending = " + sbf);

        System.out.println("We are lost -");
        sbf = new StringBuffer("We are lost -");

        astr = new Double(827.38);

        /*Here it appends string representation of Double argument 
         to this string buffer*/
        sbf.append(astr);
        System.out.println("Result after appending = " + sbf);
    }
}
    Output: 
    We are geeks and its really 
Result after appending = We are geeks and its 636.47
We are lost -
Result after appending = We are lost -827.38
  6. StringBuffer append(float f) : This method appends the string representation of the float argument to this sequence. Syntax : 
    public StringBuffer append(float a)
    Parameter: The method accepts a single parameter a which is the float value whose string representation is to be appended. Return Value: StringBuffer.append(float a) method returns a reference the string object after the operation is performed. Examples : 
    Input : 
     StringBuffer  = I love my Country   
float a =  5.2
 
Output: I love my Country 5.2
    Below program illustrates the java.lang.StringBuffer.append() method. java 
    // Java program to illustrate the
// java.lang.StringBuffer.append()
import java.lang.*;

public class Geeks {

    public static void main(String[] args)
    {

        System.out.println("We are geeks and its really ");
        StringBuffer sbf = new StringBuffer("We are geeks and its ");

        Float astr = new Float(6.47);

        /* Here it appends string representation of  Float argument
         to this string buffer */
        sbf.append(astr);
        System.out.println("Result after appending = " + sbf);

        System.out.println("We are lost -");
        sbf = new StringBuffer("We are lost -");

        astr = new Float(27.38);

        // Here it appends string representation of Float
        // argument to this string buffer
        sbf.append(astr);
        System.out.println("Result after appending = " + sbf);
    }
}
    Output: 
    We are geeks and its really 
Result after appending = We are geeks and its 6.47
We are lost -
Result after appending = We are lost -27.38
  7. StringBuffer append(int i :) This method simply appends the string representation of the int argument to this StringBuffer sequence. Syntax : 
    public StringBuffer append(int a)
    Parameter: The method accepts a single parameter a which is the int value. Return Value: The method returns a reference to this object. Examples : 
    Input :
StringBuffer = I love my Country  
int a = 55

Output: I love my Country 55
    Below program illustrates the java.lang.StringBuffer.append() method. java 
    // Java program to illustrate the
// java.lang.StringBuffer.append()
import java.lang.*;

public class Geeks {

    public static void main(String[] args)
    {

        System.out.println("We are geeks and its really ");
        StringBuffer sbf = new StringBuffer("We are geeks and its ");

        Integer astr = new Integer(827);

        /*Here it appends string representation of  Integer argument to
        argument to this string buffer*/
        sbf.append(astr);
        System.out.println("Result after appending = " + sbf);

        System.out.println("We are lost -");
        sbf = new StringBuffer("We are lost -");

        astr = new Integer(515);

        // Here it appends string representation of Integer
        // argument to this string buffer
        sbf.append(astr);
        System.out.println("Result after appending = " + sbf);
    }
}
    Output: 
    We are geeks and its really 
Result after appending = We are geeks and its 827
We are lost -
Result after appending = We are lost -515
  8. StringBuffer append(Long l) : This method simply appends the string representation of the long argument to this StringBuffer sequence. Syntax : 
    public StringBuffer append(Long a)
    Parameter : The method accepts a single parameter a which is the long value. Return Value: The method returns a string object after the append operation is performed. Examples : 
    Input :
StringBuffer  = I love my Country
Long a = 591995

Output: I love my Country 591995
    Below program illustrates the java.lang.StringBuffer.append() method. java 
    // Java program to illustrate the
// java.lang.StringBuffer.append()
import java.lang.*;

public class Geeks {

    public static void main(String[] args)
    {

        System.out.println("We are geeks and its really ");
        StringBuffer sbf = new StringBuffer("We are geeks and its ");

        Long astr = new Long(827);

        /* Here it appends string representation of  Long argument
         to this string buffer*/
        sbf.append(astr);
        System.out.println("Result after appending = " + sbf);

        System.out.println("We are lost -");
        sbf = new StringBuffer("We are lost -");

        astr = new Long(515);

        /* Here it appends string representation of Long argument
          to this string buffer*/
        sbf.append(astr);
        System.out.println("Result after appending = " + sbf);
    }
}
    Output: 
    We are geeks and its really 
Result after appending = We are geeks and its 827
We are lost -
Result after appending = We are lost -515
  9. StringBuffer append(CharSequence a) : This method is used to append the specified CharSequence to this sequence. Syntax : 
    public StringBuffer append(CharSequence a)
    Parameter: The method accepts a single parameter a which is the CharSequence value. Return Value: The method returns a string object after the append operation is performed. Examples : 
    Input :
StringBuffer  = I love my Country   
CharSequence a =  abcd

Output : I love my Countryabcd
    Below program illustrates the java.lang.StringBuffer.append() method. java 
    // Java program to illustrate the
// java.lang.StringBuffer.append()
import java.lang.*;

public class Geeks {

    public static void main(String[] args)
    {

        StringBuffer sbf = new StringBuffer("Geeksfor");
        System.out.println(" string buffer = " + sbf);

        CharSequence chSeq = "geeks";

        // Appends the CharSequence
        sbf.append(chSeq);

        // Print the string buffer after appending
        System.out.println("After append = " + sbf);
    }
}
    Output: 
    string buffer = Geeksfor
After append = Geeksforgeeks
  10. StringBuffer append(CharSequence chseq, int start, int end) : This method is used to append a subsequence of the specified CharSequence to this StringBuffer. Syntax : 
    StringBuffer append(CharSequence chseq, int start, int end)
    Parameter : The method accepts a three parameter:
    • chseq(CharSequence): This refers to the CharSequence value.
    • start(Integer): This refers to the starting index of the subsequence to be appended..
    • end(Integer): This refers to the end index of the subsequence to be appended.
    Return Value : The method returns the string after the append operation is performed. Examples : 
    Input :
StringBuffer = Geeksforgeeks
CharSequence chseq = abcd1234
int start = 2
int end = 7

Output :Geeksforgeekscd123
    Below program illustrates the java.lang.StringBuffer.append() method: java 
    // Java program to illustrate the
// java.lang.StringBuffer.append()

import java.lang.*;

public class Geeks {

    public static void main(String[] args)
    {

        StringBuffer sbf = new StringBuffer("we are the ");
        System.out.println(" string buffer = " + sbf);

        CharSequence chSeq = "wegeekss";

        /* It appends the CharSequence with start index 2 and 
       end index 4 */
        sbf.append(chSeq, 2, 7);

        System.out.println("After append string buffer = " + sbf);
    }
}
    Output: 
    string buffer = we are the 
After append string buffer = we are the geeks
  11. StringBuffer append(Object obj) : This method is used to append the string representation of the Object argument to the StringBuffer. Syntax : 
    StringBuffer append(Object obj)
    Parameter : The method accepts a single parameter obj which refers to the object needed to be appended. Return Value : The method returns the string after performing the append operation. Below programs illustrate the java.lang.StringBuffer.append() method. Program : java 
    // Java program to illustrate the
// java.lang.StringBuffer.append()

import java.lang.*;

public class Geeks {

    public static void main(String[] args)
    {

        StringBuffer sbf = new StringBuffer("Geeksfor");
        System.out.println("string buffer = " + sbf);

        Object objectvalue = "geeks";

        // Here it appends the Object value
        sbf.append(objectvalue);

        System.out.println("After appending result is = " + sbf);
    }
}
    Output: 
    string buffer = Geeksfor
After appending result is = Geeksforgeeks
  12. StringBuffer append(String istr) : This method is used to append the specified string to this StringBuffer. Syntax : 
    StringBuffer append(String istr)
    Parameter : The method accepts a single parameter istr of String type which refer to the value to be appended. Return Value : The method returns a specified string to this character sequence. Below program illustrates the java.lang.StringBuffer.append() method. java 
    // Java program to illustrate the
// java.lang.StringBuffer.append()

import java.lang.*;

public class Geeks {

    public static void main(String[] args)
    {

        StringBuffer sbf = new StringBuffer("Geeksfor");
        System.out.println("string buffer = " + sbf);

        String strvalue = "geeks";

        // Here it appends the Object value
        sbf.append(strvalue);

        System.out.println("After appending result is = " + sbf);
    }
}
    Output: 
    string buffer = Geeksfor
After appending result is = Geeksforgeeks
  13. StringBuffer append(StringBuffer sbf) : This method is used to append the specified StringBuffer to this sequence or StringBuffer. Syntax : 
    public StringBuffer append(StringBuffer sbf)
    Parameter : The method accepts a single parameter sbf refers to the StringBuffer to append. Return Value : The method returns StringBuffer to this sequence. Below program illustrates the java.lang.StringBuffer.append() method. java 
    // Java program to illustrate the
// java.lang.StringBuffer.append()

import java.lang.*;

public class Geeks {

    public static void main(String[] args)
    {

        StringBuffer sbf1 = new StringBuffer("Geeks");
        System.out.println("String buffer 1 = " + sbf1);

        StringBuffer sbf2 = new StringBuffer("forgeeks ");
        System.out.println("String buffer 2 = " + sbf2);

        // Here it appends stringbuffer2 to stringbuffer1
        sbf1.append(sbf2);

        System.out.println("After appending the result is = " + sbf1);
    }
}
    Output: 
    String buffer 1 = Geeks
String buffer 2 = forgeeks 
After appending the result is = Geeksforgeeks

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