Java: Check whether a substring appears before a period(.) within a given string

Last update on May 21 2025 12:48:59 (UTC/GMT +8 hours)

73. Substring Before Period

Write a Java program to check whether a substring appears before a period(.) within a given string.

Visual Presentation:

Sample Solution:

Java Code:

import java.util.*;

// Define a class named Main
public class Main {

    // Method to check if 'abc' appears before a period in the given string
    public Boolean abcBeforePeriod(String stng) {
        int len = stng.length(); // Get the length of the input string
        String abc = "abc"; // Create a string variable 'abc' to match against
        Boolean match = false; // Initialize a boolean variable 'match' to false

        if (len < 3)
            return false; // If the length of the string is less than 3, return false as 'abc' cannot appear

        for (int i = 0; i < len - 2; i++) {
            // Extract a substring of length 3 starting from the current index 'i'
            String temp = stng.substring(i, i + 3);

            // Check if the extracted substring matches 'abc' and it's at the beginning of the string
            if (temp.compareTo(abc) == 0 && i == 0)
                match = true;
            // Check if the extracted substring matches 'abc' and the character before it is not a period ('.')
            else if (temp.compareTo(abc) == 0 && stng.charAt(i - 1) != 46)
                match = true;
        }
        return match; // Return the boolean variable indicating if 'abc' appeared before a period
    }

    // Main method to execute the program
    public static void main(String[] args) {
        Main m = new Main(); // Create an instance of the Main class

        String str1 = "testabc.test"; // Input string to be checked

        // Display the given string and check if 'abc' appears before a period using abcBeforePeriod method
        System.out.println("The given string is: " + str1);
        System.out.println("Does 'abc' appear before a period? " + m.abcBeforePeriod(str1));
    }
}

Sample Output:

The given strings is: testabc.test
Is 'abc' appear before period? true

The given string is: test.abctest
Is 'abc' appear before period? false

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Java program to determine if a specified substring occurs before the first period in a string.
• Write a Java program to check if a given substring appears in the segment preceding a period.
• Write a Java program to search for a substring only in the portion of a string that comes before a period.
• Write a Java program to verify if a specific substring is found prior to any occurrence of a period.

Go to:

• Java String Exercises Home ↩
• Java Exercises Home ↩

PREV : Contains P?P Pattern.
NEXT : Prefix Appears Elsewhere.

Java Code Editor:

Improve this sample solution and post your code through Disqus