How do I find a string in Java?

In order to check if a String has only Unicode letters in Java, we use the isDigit() and charAt() methods with decision-making statements . The isLetter(int codePoint) method determines whether the specific character (Unicode codePoint) is a letter. It returns a boolean value, either true or false.

The Java String contains() method is used to check whether the specific set of characters are part of the given string or not. It returns a boolean value true if the specified characters are substring of a given string and returns false otherwise. It can be directly used inside the if statement.

Simple Approach: The idea is to run a loop from start to end and for every index in the given string check whether the sub-string can be formed from that index . This can be done by running a nested loop traversing the given string and in that loop run another loop checking for sub-string from every index.

The fastest way to check if a string contains a particular word or substring is with the help of String. indexOf() method . This method returns the index of the first occurrence of the specified substring inside the calling String object.