Java String contains() Method

What is String?

A string class in Java is a collection of characters that a script interprets literally. A string is an object that symbolises a group of characters. It uses Java.lang. The String class is used to create a string object.

  • Numerous methods, including compare(), concat(), equals(), split(), length(), replace(), compareTo(), intern(), and substring(), are available in the Java String class.

To know more about String Class in java read the complete article.

String contains() Method:

The contains() method of the Java String class looks through the string’s characters in order. If the series of char values is present in the string, it returns true; otherwise, it returns false.

  • The Java String contains() method checks whether a string contains a sequence of characters and Returns true if the characters exist and false if not.

  • For example, you may check to see if the substring “PrepInsta” is included in the string “PrepInsta Prime is learning Platform.” Java’s string contains() function comes in handy in these circumstances.

  • NullPointerException – if the returned value is null

Syntax:

public boolean contains(CharSequence s)

Parameters:

s - the sequence to search for

Let’s look at a string-related Java program where the Java String contains() method is used to perform an operation on the given string.

Example 1 : Determine whether a string contains a particular character sequence:

Run
public class Main {
  public static void main(String[] args) {
    String myStr = "PrepInsta";
    System.out.println(myStr.contains("Prep"));
  }
}

Output

true

Example 2 : Determine whether a string contains a particular character sequence

Run
public class Main {
  public static void main(String[] args) {
    String myStr = "Welcome to PrepInsta";
    System.out.println(myStr.contains("Prep"));
    System.out.println(myStr.contains("Insta"));
    System.out.println(myStr.contains("Prime"));
  }
}

Output

true
true
false

Examples 3: Determine whether a string contains a particular character sequence.

Run
public class Main {
  public static void main(String[] args) {
    String myStr = "PrepInsta is a online learing platfrom";
    System.out.println(myStr.contains("Learn"));
    System.out.println(myStr.contains("from"));
    System.out.println(myStr.contains("Insta"));
    System.out.println(myStr.contains("line"));
  }
}  

Output

false
true
true
true

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