Java.lang.StringBuilder.replace() Method



The java.lang.StringBuilder.replace() method replaces the characters in a substring of this sequence with characters in the specified String. The substring begins at the specified start and extends to the character at index end - 1 or to the end of the sequence if no such character exists.


Following is the declaration for java.lang.StringBuilder.replace() method

public StringBuilder replace(int start, int end, String str)


  • start − This is the beginning index, inclusive.

  • end − This is the ending index, exclusive.

  • str − This is the String that will replace previous contents.

Return Value

This method returns this object.


StringIndexOutOfBoundsException − if start is negative, greater than length(), or greater than end.


The following example shows the usage of java.lang.StringBuilder.replace() method.

package com.tutorialspoint;

import java.lang.*;

public class StringBuilderDemo {

   public static void main(String[] args) {
      StringBuilder str = new StringBuilder("Java Util Package");
      System.out.println("string = " + str);
      // replace substring from index 5 to index 9
      str.replace(5, 9, "Lang");
      // prints the StringBuilder after replacing
      System.out.println("After replacing: " + str);

Let us compile and run the above program, this will produce the following result −

string = Java Util Package
After replacing: Java Lang Package