The charAt(int index) method of StringBuilder Class is used to return the character at the specified index of String contained by StringBuilder Object. The index value should lie between 0 and length()-1.
Syntax:
public char charAt(int index)
Parameters: This method accepts one int type parameter index which represents index of the character to be returned.
Return Value: This method returns character at the specified position.
Exception: This method throws IndexOutOfBoundsException when index is negative or greater than or equal to length().
Below programs demonstrate the charAt() method of StringBuilder Class:
Example 1:
// Java program to demonstrate // the charAt() Method. class GFG {
public static void main(String[] args)
{
// create a StringBuilder object
StringBuilder str = new StringBuilder();
// add the String to StringBuilder Object
str.append( "Geek" );
// get char at position 1
char ch = str.charAt( 1 );
// print the result
System.out.println( "StringBuilder Object"
+ " contains = " + str);
System.out.println( "Character at Position 1"
+ " in StringBuilder = " + ch);
}
} |
StringBuilder Object contains = Geek Character at Position 1 in StringBuilder = e
Example 2:
// Java program demonstrate // the charAt() Method. class GFG {
public static void main(String[] args)
{
// create a StringBuilder object
// with a String pass as parameter
StringBuilder
str
= new StringBuilder( "WelcomeGeeks" );
// print string
System.out.println( "String is "
+ str.toString());
// loop through string and print every Character
for ( int i = 0 ; i < str.length(); i++) {
// get char at position i
char ch = str.charAt(i);
// print char
System.out.println( "Char at position "
+ i + " is " + ch);
}
}
} |
String is WelcomeGeeks Char at position 0 is W Char at position 1 is e Char at position 2 is l Char at position 3 is c Char at position 4 is o Char at position 5 is m Char at position 6 is e Char at position 7 is G Char at position 8 is e Char at position 9 is e Char at position 10 is k Char at position 11 is s
Example 3: To demonstrate IndexOutOfBoundException
// Java program to demonstrate // IndexOutOfBound exception thrown by the charAt() Method. class GFG {
public static void main(String[] args)
{
try {
// create a StringBuilder object
// with a String pass as parameter
StringBuilder
str
= new StringBuilder( "WelcomeGeeks" );
// get char at position i
char ch = str.charAt(str.length());
// print char
System.out.println( "Char at position "
+ str.length() + " is "
+ ch);
}
catch (Exception e) {
System.out.println( "Exception: " + e);
}
}
} |
Exception: java.lang.StringIndexOutOfBoundsException: String index out of range: 12
Reference:
https://docs.oracle.com/javase/10/docs/api/java/lang/StringBuilder.html#charAt(int)