StringBuilder Practice

01.StringBuilder_Exercise.java

Given:

StringBuilder b1 = new StringBuilder("snorkler");
StringBuilder b2 = new StringBuilder("yoodler");

b1.append(b2.substring(2,5).toUpperCase());
//b1 = snorkler     b2 = yoodler

b1.append("odl".toUpperCase());
//b1 = snorkler     b2 = yoodler

b1.append("ODL");
//b1 = snorklerODL  b2 = yoodler

02.StringBuilder_Exercise.java

Given:

StringBuilder b1 = new StringBuilder("snorkler");
StringBuilder b2 = new StringBuilder("yoodler");

b2.insert(3, b1.append("a"));
//b1 = snorklera     //b2 = yoodler

b2, insert(3, "snorklera");
//b1 = snorklera    //b2 = yoosnorkleradler

03.StringBuilder_Exercise.java

Given:

StringBuilder b1 = new StringBuilder("snorkler");
StringBuilder b2 = new StringBuilder("yoodler");

b1.replace(3, 4, b2.substring(4).append(b2.append(false)));
//b1 = "snorkler"     b2 = "yoodlerfalse"

b1.replace(3, 4, b2.substring(4).append("yoodlerfalse"));
//b1 = "snorkler"     b2 = "lerfalseyoodlerfalse"

b1.replace(3, 4, "lerfalseyoodlerfalse");
//b1 = "snolerfalseyoodlerfalsekler" b2 = "lerfalseyoodlerfalse"

StringBuilder.insert().java

Java.lang.StringBuilder.insert() Method
  
// Description
// The java.lang.StringBuilder.insert(int offset, String str) method inserts the 
// string into this character sequence.

// The characters of the String argument are inserted, in order, into this sequence 
// at the indicated offset, moving up any characters originally above that position 
// and increasing the length of this sequence by the length of the argument.

//Declaration

public StringBuilder insert(int offset, String str)

//Parameters
//  offset -- This is the offset.

//  str -- This is the value of string.

//Return Value

//Exception
StringIndexOutOfBoundsException -- if the offset is invalid.

//Example

package com.tutorialspoint;

import java.lang.*;

public class StringBuilderDemo {

   public static void main(String[] args) {
  
   StringBuilder str = new StringBuilder("tutorials website");
   System.out.println("string = " + str);
        
   // insert string value at offset 9
   str.insert(9, "point");

   // prints StringBuilder after insertion
   System.out.print("After insertion = ");
   System.out.println(str.toString());
   }      
}  
//Let us compile and run the above program, this will produce the following result:

string = tutorials website
After insertion = tutorialspoint website

StringBuilder.substring().java

//Java.lang.StringBuilder.substring() Method

//Description:

// The java.lang.StringBuilder.substring(int start, int end) method returns a new 
// String that contains a subsequence of characters currently contained in this sequence. 
// The substring begins at the specified start and extends to the character at index end - 1.

//Declaration

public String substring(int start, int end)

//Parameters
//start -- This is the beginning index, inclusive.
//end   -- This is the ending index, exclusive.

//Return Value
//This method returns the new string.

//Exception
StringIndexOutOfBoundsException 
//-- if start or end are negative or greater than length(), or start is greater than end.

//Example

package com.tutorialspoint;

import java.lang.*;

public class StringBuilderDemo {

   public static void main(String[] args) {
  
   StringBuilder str = new StringBuilder("admin");
   System.out.println("string = " + str);

   // prints substring from index 3
   System.out.println("substring is = " + str.substring(3));

   /* prints substring from index 1 to 4 excluding character
   at 4th index */
   System.out.println("substring is = " + str.substring(1, 4));
   }
}
Let us compile and run the above program, this will produce the following result:

string = admin
substring is = in
substring is = dmi