String contains() Method in Java with Example

What is contains()method in Java?

The contains() method is Java method to check if String contains another substring or not. It returns boolean value so it can use directly inside if statements.

Syntax of String "Contain" method

public boolean String.contains(CharSequence s)

Parameters

S − This is the sequence to search

Return Value

This method returns true only if this string contains "s" else false.

Exception

NullPointerException − if the value of s is null.

Example 1:

public class Sample_String {
    public static void main(String[] args) {
        String str_Sample = "This is a String contains Example";
        //Check if String contains a sequence
        System.out.println("Contains sequence 'ing': " + str_Sample.contains("ing"));
        System.out.println("Contains sequence 'Example': " + str_Sample.contains("Example"));
        //String contains method is case sensitive  
        System.out.println("Contains sequence 'example': " + str_Sample.contains("example"));
        System.out.println("Contains sequence 'is String': " + str_Sample.contains("is String"));
    }
}

Output:

Contains sequence 'ing': true
Contains sequence 'Example': true
Contains sequence 'example': false
Contains sequence 'is String': false

When to use Contains() method?

It is a common case in programming when you want to check if specific String contains a particular substring. For example, If you want to test if the String "The big red fox" contains the substring "red." This method is useful in such situation.

Example 2: Java String contains() method in the if else Loop

public class IfExample {
    public static void main(String args[]) {
        String str1 = "Java string contains If else Example";
        // In If-else statements you can use the contains() method

        if (str1.contains("example")) {
            System.out.println("The Keyword :example: is found in given string");
        } else {
            System.out.println("The Keyword :example: is not found in the string");
        }
    }
}

Output:

The Keyword :example: is not found in the string