Java String startsWith and endsWith
“Variables are said to be memory spaces or containers holding program data that will be used within the codes at several parts. One of those variables, strings, are very well-known variables in object-oriented programming languages like Java and C++. Strings hold a bunch of alphabetical characters, words, and special characters like space. We can play with strings in many ways using Java’s variety of functions. From many of those functions, we have endsWith, and startsWith functions used to get the information regarding the prefix and suffix of the string. Let’s move towards the implementation to get a clear idea about both the functions of Java.”
Example 01: String startsWith() Function
We are going to use the startsWith() function of Java in this illustration to see if the string variable starts with the specific patterns or not. This is turning out to be the very basic one. So, we will not be complicating the script to get the most out of the code. Starting with launching the Java tool, i.e., Eclipse IDE, we have created a new Java file named “test.java”. The code must be started with the initialization of a public class, i.e., the class name should be similar to the title of a file.
The class contains our main() function, which is going to be the only function in this example. The method starts with the initialization of a string variable “S”. This string contains a single word, “Eclipse,” in it. At the 5th line, we have tried the “System.out.println” statement to display a string “S” at the output, i.e., System is a library, the “out” keyword represents a class, and the println() is the function from this class of Java.
In the next 3 lines, we have been using the same println() function statement with the “startsWith” function in its parameters to check for the patterns. This function “startsWith” would use three different string patterns and verify if the main string “S” starts with the specified patterns or not. The Boolean result would be returned and displayed on the console, i.e., true or false. In the illustration shown below, only the 1st statement occupies the true starting pattern of a string “S”; thus, it will be returning true.
On this Java program completion, we executed it and got the string “S” printed out at the Eclipse IDE console. The use of the startsWith function in the first println() function returns true as the pattern “Ecl” is the starting string of “S” while the others return false, i.e., didn’t match.
Example 02: String endsWith() Function
It’s time to explore the endsWith function of Java to see if the string ends with a specific pattern or not. For this, we are using the first example’s code by updating it a little. The program code starts with the “test” class that contains its main() driver function. The same string variable “S” has been initialized with a value “Eclipse,” and it got printed out using the “System.out.println” function statement.
After this, we are going to utilize the endsWith function in the parameters of the “System.out.println” function statement to check whether the string “S” ends with the specified pattern string or not. We have used a total of three string patterns to be checked within the endsWith() function statement, i.e., using the “System.out.println” function statement 3 times in a row. As the string “Eclipse” ends with the “se” pattern only, this program is going to return true for the second println statement only.
After the execution, it prints the string along with the Boolean results it got from the use of the endsWith function within the println() statements. Only the second println() statement returns true, i.e., the patterns matched as the string “Eclipse” ends with the “se” substring.
Example 03: String startsWith() & endsWith Functions
This program example is going to elaborate both functions in one java program, i.e., endsWith and startsWith. The program uses 2 classes, “Main” and the “test” class. The “test” class holds its main() function and the “Main” class holds 2 user-defined functions, i.e., “Start” and “End”. This program got executed from the main() function of the “test” class and created a new object “t” for the other class “Main”. As the object “t” got created, we can successfully fetch the contents of the “Main” class. The Main() function prints out the string “S” that has been initialized in the Main() class.
After this, the object “t” is used to call the “Start()” and “End” functions consecutively. Now, the Start() function of the Main() class got executed first. It starts with the “if” statement that has been making use of the “startsWith” function taking “our” as a substring pattern to be matched and the number “6” as the index to be taken as the first position, i.e., if the pattern found at “8” index, it will print the success message otherwise the else part would display its specified message string.
Another “if” statement is also used here to see if the substring “test” has started at the 11th index of a string “S” using the startsWith() function or not. The “End” function uses the “endsWith” function within its “if” statements that are used twice to check whether the substring “our” and “string” are at the end of a string “S” or not. Here, the first “if” statement of the “Start” function and the second “if” statement of the “End” function will return true, i.e., patterns got matched at the specific positions.
After this program execution, we got the expected result and string displayed in the console.
Conclusion
The introduction for this tutorial is about the use of variables in programming and the significance of strings in Java. After this, we elaborated the use of startsWith and endsWith functions separately in the first two basic illustrations. In the end, we have explained both functions at the broad level of Java programming, i.e., by specifying the substring pattern and the specific index number of a string where we want to check the position of a substring.
About the author
Saeed Raza
Hello geeks! I am here to guide you about your tech-related issues. My expertise revolves around Linux, Databases & Programming. Additionally, I am practicing law in Pakistan. Cheers to all of you.