Java program to extract a substring from a string :
In this Java programming tutorial, we will learn how to extract a substring from a user given string. The program will ask the user to enter a string and first and the second index of the substring. Then it will print out the substring of that string. Let’s take a look at the program :
Java program :
import java.util.*;
public class Main {
public static void main(String[] args) {
//1
Scanner scanner = new Scanner(System.in);
String inputString;
//2
int startIndex;
int endIndex;
//3
System.out.println("Enter a string : ");
inputString = scanner.nextLine();
//4
System.out.println("Enter the first index of the substring : ");
startIndex = scanner.nextInt();
//5
System.out.println("Enter the second index of the substring : ");
endIndex = scanner.nextInt();
//6
char[] ch = new char[endIndex - startIndex + 1];
inputString.getChars(startIndex, endIndex + 1, ch, 0);
//7
System.out.println("Output : " + String.valueOf(ch));
}
}
Explanation :
The commented numbers in the above program denote the step numbers below :
-
Create one Scanner object to read the user input values.Create one string inputString to store the user input string.
-
Create two variables to store the start and end index of the substring.
-
Ask the user to enter a string. Scan it and store it in inputString variable.
-
Ask the user to enter the first index , read and store it in startIndex variable.
-
Ask the user to enter the end index, read and store it in endIndex variable.
-
Create one character array ch to read and store the substring as character array.For this we are using getChars method.It takes 4 arguments :
First one is the start index of the substring.
* Second one is the ending index of the string. If we pass _5_ as ending index, it will get the sub array up to _4th_ index.
* Third one is the character array to store the sub array.
* Fourth one is the starting index of the _character array_ where we are storing.- Finally, convert the character array to a string using String.valueOf() and print out the string.
Sample output :
Enter a string :
hello
Enter the first index of the substring :
1
Enter the second index of the substring :
4
Output : ell
Hello World
Enter the first index of the substring :
1
Enter the second index of the substring :
6
Output : ello W