StringBuffer replace() Method in Java with Examples (original) (raw)

Last Updated : 13 Dec, 2021

The StringBuffer.replace() is the inbuilt method which is used to replace the characters in a substring of this sequence with the characters in the specified String. Here simply the characters in the substring are removed and other char is inserted at the start.
Syntax :

public StringBuffer replace(int first, int last, String st)

Parameters : The method accepts three parameters.

• first : This is of integer type which refers to the starting index.
• last : This is of integer type which refers to the ending index.
• st : This is of string type which refer to the String that will replace previous contents.

Return Value : The method returns this object after performing the above mentioned operations.
Exception : If the first is negative, greater than length(), or greater than last then StringIndexOutOfBoundsException.
Examples :

Input: StringBuffer= "The first planet of solar system is merrhxy" first = 39 last = 42 st = "cur"

Output: The first planet of solar system is mercury

Below programs illustrate the java.lang.StringBuffer.replace() method:
Program 1:

java

import java.lang.*;

public class Geeks {

`` public static void main(String[] args)

`` {

`` StringBuffer sbf = new StringBuffer("Welcome to Geekshssgeeks");

`` System.out.println("string buffer = " + sbf);

`` sbf.replace( 15 , 18 , " for ");

`` System.out.println("After replacing string buffer= " + sbf);

`` }

}

Output:

string buffer = Welcome to Geekshssgeeks After replacing string buffer= Welcome to Geekforsgeeks

Program 2: When negative index is passed:

java

import java.lang.*;

public class Geeks {

`` public static void main(String[] args)

`` {

`` StringBuffer sbf = new StringBuffer("Welcome to Geekshssgeeks");

`` System.out.println("string buffer = " + sbf);

`` sbf.replace(- 15 , - 18 , " for ");

`` System.out.println("After replacing string buffer= " + sbf);

`` }

}

Output:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: -15 at java.lang.AbstractStringBuilder.replace(AbstractStringBuilder.java:851) at java.lang.StringBuffer.replace(StringBuffer.java:452) at Geeks.main(Geeks.java:14)

Program 3: When index passed is greater than length

java

import java.lang.*;

public class Geeks {

`` public static void main(String[] args)

`` {

`` StringBuffer sbf = new StringBuffer("Welcome to Geekshssgeeks");

`` System.out.println("string buffer = " + sbf);

`` sbf.replace( 215 , 218 , " for ");

`` System.out.println("After replacing string buffer= " + sbf);

`` }

}

Output:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: start > length() at java.lang.AbstractStringBuilder.replace(AbstractStringBuilder.java:853) at java.lang.StringBuffer.replace(StringBuffer.java:452) at Geeks.main(Geeks.java:14)