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