Java StringBuilder Contains Example (StringBuffer)

Java StringBuilder contains example shows how to check if StringBuilder contains a specified character or String. This example also shows how to check the same in the StringBuffer object.

How to check if StringBuilder contains character or String specified (StringBuffer)?

Java String class provides contains method which checks if the specified character sequence is contained within the String.

1	public boolean contains(CharSequence s)

This method returns a boolean depending upon whether the String contains a specified sequence.

Unlike the String class, StringBuilder and StringBuffer classes do not provide a contains method. However, the StringBuilder/StringBuffer class provides indexOf method.

1	public int indexOf(String str)

The indexOf method returns the index of the first occurrence of the specified substring. If the substring is not found, it returns -1. In the below example, we are going to use the indexOf method of the StringBuilder class to build our own version of the contains method.

public class JavaStringBuilderContainsExample {

public static void main(String[] args) {

//StringBuilder object

StringBuilder sb = new StringBuilder("One Two Three");

System.out.println( contains(sb, "One") );

System.out.println( contains(sb, "Two") );

System.out.println( contains(sb, "Five") );

}

public static boolean contains(StringBuilder sb, String findString){

* if the substring is found, position of the match is

* returned which is >=0, if not -1 is returned

return sb.indexOf(findString) > -1;

}

Output

true

false

As you can see from the output, the contains method returns true for the first two method calls and false for the third one as StringBuilder does not contain the “Five” text. The above code also works for StringBuffer as they have similar APIs.