StringBuilder capacity() in Java with Examples

The capacity() method of StringBuilder Class is used to return the current capacity of StringBUilder object. The capacity is the amount of storage available to insert new characters.
Syntax:

public int capacity()

Return Value: This method returns the current capacity of StringBuilder Class.
Below programs demonstrate the capacity() method of StringBuilder Class:
Example 1:

Java

// Java program to demonstrate
// the capacity() Method.

class GFG {
    public static void main(String[] args)
    {

        // create a StringBuilder object,
        // default capacity will be 16
        StringBuilder str = new StringBuilder();

        // get default capacity
        int capacity = str.capacity();

        System.out.println("Default Capacity of StringBuilder = "
                           + capacity);

        // add the String to StringBuilder Object
        str.append("Geek");

        // get capacity
        capacity = str.capacity();

        // print the result
        System.out.println("StringBuilder = " + str);
        System.out.println("Current Capacity of StringBuilder = "
                           + capacity);
    }
}

Output

Default Capacity of StringBuilder = 16
StringBuilder = Geek
Current Capacity of StringBuilder = 16

Example 2:

Java

// Java program to demonstrate
// the capacity() Method.

class GFG {
    public static void main(String[] args)
    {
        // create a StringBuilder object
        // with a String passed as parameter
        StringBuilder
            str
            = new StringBuilder("WelcomeGeeks");

        // get capacity
        int capacity = str.capacity();

        // print the result
        System.out.println("StringBuilder = " + str);
        System.out.println("Capacity of StringBuilder = "
                           + capacity);
    }
}

Output:

StringBuilder = WelcomeGeeks
Capacity of StringBuilder = 28

Reference:
https://docs.oracle.com/javase/10/docs/api/java/lang/StringBuilder.html#capacity()