The String class represents character strings. Duration: 1 week to 2 week. Devuelve un valor booleano para que pueda usarse directamente dentro de sentencias if. Use String.contains() to find is a substring is present in given string or not. In plain Java, we can iterate over characters of the string and check if each character is an alphabet or not. The String contains() method checks whether the specified string (sequence of characters) is present in the string or not. String.contains () – Case Sensitive. As a start, we'll show how to use the String.contains() method to achieve our goal. The contains() method is helpful to find a char-sequence in the string. Examples: Input: GeeksforGeeks Output: true Explanation: The given string contains only alphabets so the output is … Java String contains () method was introduced in java 1.5 release as a utility method. Returns true if the characters exist and false if not. String buffers support mutable strings. Otherwise, if it does not contains the String, it will return false. Java String contains () method checks whether a particular sequence of characters is part of a given string or not. The Java String contains() searches a substring in the given string. package com.mkyong; public class JavaExample1 { public static void main(String [] args) { String name = "mkyong is learning Java 123" ; System.out.println (name.contains ( "Java" )); // true System.out. The CharSequence interface is a readable sequence of char values, found in the java.lang package. It returns the index of the first occurrence of a substring within a String, and offers a few constructors to choose from: We can either search for a singl… If you want to report an error, or if you want to make a suggestion, do not hesitate to send us an e-mail: W3Schools is optimized for learning and training. In this article, we'll take a look at how to check if an array contains a value or element in Java. s … Examples might be simplified to improve reading and learning. The contains() method searches case sensitive char sequence. Definition and Usage. Checkout ArrayList contains example, String contains example, check if array contains value or check if String contains number example to learn more. Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content. It can be directly used inside the if statement. Please remember that this method is case sensitive.. 1.1. JavaTpoint offers too many high quality services. For example, the length of a string can be found with the length () method: The .indexOf() method is a bit more crude than the .contains() method, but it's nevertheless the underlying mechanism that enables the .contains()method to work. Java String class provides a lot of methods to perform operations on strings such as compare(), concat(), equals(), split(), length(), replace(), compareTo(), intern(), substring() etc.. The contains () method returns either True or False. The java.lang.String.contains() method returns true if and only if this string contains the specified sequence of char values. String contains () method internally uses String indexOf method, below code snippet shows the contains () method definition. Introduction Whether in Java, or any other programming language, it is a common occurrence to check if an array contains a value. Next, let's try String.contains. In this example, contains returns true because “Hey” is found. Nó trả về true nếu chuỗi các giá trị char được tìm thấy trong chuỗi này, nếu không trả về false. true if sequence of char value exists, otherwise false. Method syntax. 1.1 Check if a String Array contains a certain value “A”. In this tutorial, you will learn about the Java String contains… Assert.assertTrue("Hey Ho, let's go".contains("Hey")); If the string is not found, contains … Java ArrayList.contains() - In this tutorial, we will learn about the ArrayList.contains() function, and learn how to use this function to check if this ArrayList contains specified element, with the help of examples. The contains () method checks whether a string contains a sequence of characters. It returns true if sequence of char values are found in this string otherwise returns false. NullPointerException − if the value of s is null. Phương thức contains trong Java String . This example is a part of Java StringBuffer tutorial and Java StringBuilder tutorial. For example: "; str.contains("Java"); // true str.contains("Node.js"); // false The java string contains () method searches the sequence of characters in this string. Returns true if the characters exist and false if not. 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