Java string contains() Method

Posted in Java Tutorial

Updated on Jan 15, 2024

By Mari Selvan

👁️ 33 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In Java programming, manipulating strings is a common and crucial task.

The contains() method is a built-in method in the java.lang.String class that checks whether a particular sequence of characters (substring) is present within the string.

In this tutorial, we'll explore the usage and functionality of the contains() method in Java.

💡 Syntax

The syntax for the contains() method is straightforward:

Syntax

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public boolean contains(CharSequence sequence)

sequence: The substring that you want to check for within the string.

📄 Example

Let's dive into an example to illustrate how the contains() method works.

StringContainsExample.java

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public class StringContainsExample {
  public static void main(String[] args) {
    String text = "Hello, Java Programming!";

    // Check if the string contains a specific substring
    boolean containsSubstring = text.contains("Java");

    // Output the result
    System.out.println("Does the string contain 'Java'? " + containsSubstring);
  }
}

💻 Output

Output

Does the string contain 'Java'? true

🧠 How the Program Works

In this example, the contains() method is used to check if the string "Hello, Java Programming!" contains the substring "Java" and prints the result.

↩️ Return Value

The contains() method returns a boolean value: true if the specified substring is found in the original string, and false otherwise.

📚 Common Use Cases

The contains() method is particularly useful when you need to determine whether a specific sequence of characters is present within a larger string. It simplifies tasks such as searching for keywords, validating input, or extracting relevant information.

📝 Notes

The contains() method is case-sensitive. If you need a case-insensitive search, you can convert the string and the substring to lowercase (or uppercase) using the toLowerCase() or toUpperCase() methods before calling contains().

🎢 Optimization

The contains() method is already optimized for efficient string searching. However, for large strings and frequent searches, consider storing the result in a variable if you need to use it multiple times to avoid redundant computations.

🎉 Conclusion

The contains() method in Java is a valuable tool for checking the presence of a substring within a string. It provides a simple and effective way to perform this task, enhancing the versatility and readability of your code.

Feel free to experiment with different strings and substrings to explore the behavior of the contains() method in various scenarios. Happy coding!