If a variable called mystring is “Hello” and we print mystring.substring(1,4). public String substring(int startIndex, int endIndex).public String substring(int startIndex).If start is greater than end, arguments are swapped: (4, 1) (1, 4). The substring () method does not change the original string. The substring () method extracts characters from start to end (exclusive). If you find this post helpful, please share it on social media.The substring() Java method returns a specified part of a given String in Java programming. The substring () method extracts characters, between two indices (positions), from a string, and returns the substring. Then the substring method will be called on the new String object and another new String object created and pointed at by the s instance. First the string 'Hello, World' will be created on the heap and a brand new String object will point at it. There are many other built-in methods in JS which really help us a lot when dealing with various things in programming. Also, when doing String s 'Hello, World'.substring(0,5) think about the order of operations. So these are the 3 different methods to get a substring in JavaScript. However, if we don’t define the second parameter, it returns up to the end of the original string (like the previous two methods do): Note: All 3 methods return the substring as a new string and they don’t change the original string. In this example, it basically counts 5 characters starting with the given startIndex and returns them as a substring. You can see the difference here: the substr( ) method expects the second parameter as a length instead of an endIndex: length: number of characters to be included (optional).The substr( ) method also returns a substring of the original string and expects two parameters as: string.substring(startIndex, length) But I will still briefly explain what it does because you might see it in older projects. String str 'Hello World' String substr str.substring (6, 11) (substr) // Output: 'World'. It returns a new string containing the original string's characters from the begIndex (inclusive) up to the endIndex (exclusive). The substr( ) MethodĪccording to the Mozilla documents, the substr( ) method is considered a legacy function and its use should be avoided. The Java substring (begIndex, endIndex) method extracts a portion of a given string. The substring () method takes two arguments: beginIndex: the beginning index of the substring. These indices determine the substring position within the original string. You can find here my other article about the slice method to see the usage for arrays. String.substring () API The String.substring () in Java returns a new String that is a substring of the given string that begins from startIndex to an optional endIndex. Note: We can use the slice( ) method also for JavaScript arrays. If startIndex is a negative number, then the first character begins from the end of the string (reverse):.If startIndex > endIndex, the slice( ) method returns an empty string.If startIndex and endIndex are greater than the length of the string, it returns an empty string.If we set both the startIndex and the endIndex, then we will get the characters between the given index numbers of the original string:.If we don’t set an ending index, then we get a substring starting from the given index number until the end of the original string:.The common points of substring( ) and slice( ) methods: An easy alternative is to use Apache Commons StringUtils.substring: public static String substring (String str, int start) Gets a substring from the specified String avoiding exceptions. The slice method also expects the same two parameters: string.slice(startIndex, endIndex) Java's substring method fails when you try and get a substring starting at an index which is longer than the string. The slice( ) method is similar to the substring( ) method and it also returns a substring of the original string. ![]() ![]() If startIndex > endIndex, then the substring method swaps the arguments and returns a substring, assuming as the endIndex > startIndex.If startIndex and endIndex are both greater than the length of the string, it returns an empty string.If startIndex = endIndex, the substring method returns an empty string. ![]() Then we get a substring starting from the 6th character until the end of the original string. However, if we set only a starting index and no ending index for this example: Now if we set the startIndex as 0 and the endIndex as 10, then we will get the first 10 characters of the original string: The first character's index is always 0 Suppose that we have the example string below: const myString = "I am learning JavaScript and it is cool!"
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