StringBuilder charAt() in Java with Examples
Last Updated :
15 Oct, 2018
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:
class GFG {
public static void main(String[] args)
{
StringBuilder str = new StringBuilder();
str.append( "Geek" );
char ch = str.charAt( 1 );
System.out.println( "StringBuilder Object"
+ " contains = " + str);
System.out.println( "Character at Position 1"
+ " in StringBuilder = " + ch);
}
}
|
Output:
StringBuilder Object contains = Geek
Character at Position 1 in StringBuilder = e
Example 2:
class GFG {
public static void main(String[] args)
{
StringBuilder
str
= new StringBuilder( "WelcomeGeeks" );
System.out.println( "String is "
+ str.toString());
for ( int i = 0 ; i < str.length(); i++) {
char ch = str.charAt(i);
System.out.println( "Char at position "
+ i + " is " + ch);
}
}
}
|
Output:
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
class GFG {
public static void main(String[] args)
{
try {
StringBuilder
str
= new StringBuilder( "WelcomeGeeks" );
char ch = str.charAt(str.length());
System.out.println( "Char at position "
+ str.length() + " is "
+ ch);
}
catch (Exception e) {
System.out.println( "Exception: " + e);
}
}
}
|
Output:
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)
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