StringBuffer & StringBuilder in Java

StringBuffer
The StringBuffer and StringBuilder classes are suitable for both assembling and modifying strings; i.e they provide methods for replacing and removing characters as well as adding them in various. Java StringBuilder class is used to create mutable (modifiable) string.

Key Points:

Used to created mutable (modifiable) string.
Mutable: Which can be changed?
Is thread-safe i.e. multiple threads cannot access it simultaneously.

Methods:

public synchronized StringBuffer append ( String s )
public synchronized StringBuffer insert ( int offset, String s )
public synchronized StringBuffer replace ( int startIndex, int endIndex, String str )
public synchronized StringBuffer delete ( int startIndex, int endIndex )
public synchronized StringBuffer reverse ()

StringBuilder
Java StringBuilder class is used to create mutable (modifiable) string. The Java StringBuilder class is same as StringBuffer class except that it is non-synchronized. The StringBuffer and StringBuilder classes are suitable for both assembling and modifying strings; i.e they provide methods for replacing and removing characters as well as adding them in various.

The code demonstrates the usage of StringBuffer and StringBuilder in Java.

A StringBuilder object is created with the initial value "Tutor". The append() method is used to concatenate the string "Joes" to it. The resulting string is printed to the console.
The insert() method is used to insert the string "Computer" at the 10th index of the StringBuilder object.
The replace() method is used to replace the characters between the 9th and 11th index with "@@@".
The delete() method is used to delete the characters between the 9th and 11th index.
The reverse() method is used to reverse the order of the characters in the StringBuilder object.
The charAt() method is used to retrieve the character at the 2nd index of the StringBuilder object.
The length() method is used to retrieve the length of the StringBuilder object.
The substring() method is used to retrieve a portion of the StringBuilder object. The first call retrieves the entire string starting from the 0th index, while the second call retrieves the string starting from the 0th index up to (but not including) the 5th index.
The setCharAt() method is used to set the character at the 0th index of the StringBuilder object to "@".
A StringBuffer object is created and its capacity is printed to the console. The append() method is used to concatenate the string "Hello" to it, and its capacity is printed again. Finally, the append() method is used to concatenate the string "java is my favourite language" to it, and its capacity is printed once more.

Source Code

public class stringBuffer_stringBuilder {
    public static void main(String args[])
    {
        //StringBuffer & StringBuilder in Java
 
        StringBuilder buffer =new StringBuilder("Tutor");
        System.out.println(buffer);
        buffer.append(" Joes");
        System.out.println(buffer);
        buffer.insert(10," Computer");
        System.out.println(buffer);
        buffer.replace(9,11,"@@@");
        System.out.println(buffer);
        buffer.delete(9,11);
        System.out.println(buffer);
        buffer.reverse();
        System.out.println(buffer);
        System.out.println(buffer.charAt(2));
        System.out.println(buffer.length());
        System.out.println(buffer.substring(0));
        System.out.println(buffer.substring(0,5));
        buffer.setCharAt(0,'@');
        System.out.println(buffer);
 
        StringBuffer sb=new StringBuffer();
        System.out.println(sb.capacity());//default 16
        sb.append("Hello");
        System.out.println(sb.capacity());//now 16
        sb.append("java is my favourite language");
        System.out.println(sb.capacity());//now (16*2)+2=34 i.e (oldcapacity*2)+2
 
    }
}

Output

Tutor
Tutor Joes
Tutor Joes Computer
Tutor Joe@@@Computer
Tutor Joe@Computer
retupmoC@eoJ rotuT
t
18
retupmoC@eoJ rotuT
retup
@etupmoC@eoJ rotuT
16
16
34

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Basic Programs

Materials

Java Materials

Abstract Window Toolkit