In other words, start index starts from 0 whereas end index starts from 1. The first and foremost way to check for the presence of a substring is the .contains() method. The Java String contains() method is used to check whether the specific set of characters are part of the given string or not. The method accepts a CharSequence and returns true if the sequence is present in the String we call the method on. The array returned by this method contains each substring of this string that is terminated by another substring that matches the given expression or is terminated by the end of the string. contains will search a substring throughout the entire String and will return true if it's found and false otherwise. How to check if str2 is contained within str1? It can be directly used inside the if statement. Java Program to Check if a string contains a substring In this example, we will learn to check if a string contains a substring using contains() and indexOf() method in Java. You can definitely use Java’s own .contains() method. How can I write a java program to check if a string is a substring of another string without using indexOf(), contains(), etc? Assert.assertTrue("Hey Ho, let's go".contains("Hey")); If the string is not found, contains … This tutorial will help you to check if the main string contains another substring in it. A String that is a part of another String is known as substring for that String object. In ECMAScript 5 or older environments, use String.prototype.indexOf , which returns -1 when a substring cannot be found: I want to check if a string contains only a single occurrence of the given substring (so the result of containsOnce("foo-and-boo", "oo") should be false).In Java, a simple and straightforward implementation would be either. the following solution uses String#length and String#equalsIgnoreCase in addition to String#substring (the method which you have already used in your code). In this example, contains returns true because “Hey” is found. There are many ways (also based on which functions/methods you use) e.g. Find below implementation. A common operation in many programming languages is to check if a string contains another string. Question – How do I check If a String contains another substring in Java? Definition and Usage. The substrings in the array are in the order in which they occur in this string. The contains() method checks whether a string contains a sequence of characters.. Returns true if the characters exist and false if not. How to Check if String contains Substring in Java Written by Rahul, Updated on May 16, 2019. Check if a String Contains a Substring in Java. To understand this example, you should have the knowledge of the following Java programming topics: I have two Strings: str1 and str2. It returns a boolean value true if the specified characters are substring of a given string and returns false otherwise. A string is a sequence of characters and an immutable object in Java. Next, let's try String.contains. In our previous article, you learned to compare two strings in Java programming language. It's provided by the String class itself and is very efficient. Java String contains() method. Here by this program we will implement contains() method. For example, here is a small sample of the methods used to achieve this in various languages: Java: String.contains(), String.indexOf(), etc. Java String substring() The java string substring() method returns a part of the string. While it's a simple and common task, the method names often differ between programming languages. Let’s call it as findMe(String subString, String mainString) . Let’s check if a substring exists in the given string. const string = "foo"; const substring = "oo"; console.log(string.includes(substring)); includes doesn’t have Internet Explorer support , though. We pass begin index and end index number position in the java substring method where start index is inclusive and end index is exclusive.