Similar idioms may be constructed for indexOf(Object) and lastIndexOf(Object), and all of the algorithms in the Collections class can be applied to a subList. Java String indexOf() The java string indexOf() method returns index of given character value or substring. The IndexOf(T) method overload searches the list from the beginning, and finds the first occurrence of the string. If it is not found, it returns -1. The index counter starts from zero. If the specified element is not found in the list. The lack of something like EqualityComparer is, in my view, one of the worst things about standard java. The following examples show how to use javafx.collections.ObservableList#indexOf() .These examples are extracted from open source projects. A List of strings is created, with one entry that appears twice, at index location 0 and index location 5. 2. The indexOf method returns the index of the first occurrence of the specified element object in the list. The following example demonstrates all three overloads of the IndexOf method. 1.3. indexOf() return value. You can vote up the ones you like or vote down the ones you don't like, and go to the original project or source file by following the links above each example. The List interface provides four methods for positional (indexed) access to list elements. If the element is present then the index of the first occurrence of the element is returned otherwise -1 is returned if the list does not contain the element. Similar idioms may be constructed for indexOf and lastIndexOf, and all of the algorithms in the Collections class can be applied to a subList. Return value is of int type. So logically, if this method returns anything other than -1, we know that the list contains the element: Java program for how to get first index of object in arraylist. The semantics of the list returned by this method become undefined if the backing list (i.e., this list) is structurally modified in any way other than via the returned list. Examples. it returns -1. index – first index position of element if element is found.-1 – if element is NOT found. Now we know how strings are indexed in Java, we can explore the Java indexOf() method. indexOf is another useful method for finding elements:. The Java.util.LinkedList.indexOf(Object element) method is used to check and find the occurrence of a particular element in the list. The following examples show how to use java.util.List#indexOf() .These examples are extracted from open source projects. ArrayList get index of element. Lists (like Java arrays) are zero based. The Java string indexOf() method is used to retrieve the index value associated with a particular character or substring in a string. If the character does not occur in the string, indexOf() returns -1. Similarly, use the lastIndexOf method of the LinkedList class to find the last occurrence of the specified element in the list. indexOf Java. int indexOf(Object element) This method returns the index of the first occurrence of the specified element in the given list, or -1 if the list doesn't contain the element.. You can vote up the ones you like or vote down the ones you don't like, and go to the original project or source file by following the links above each example. Internal implementation It means that if you want to use objects in a collection such as an ArrayList or HashSet, you are stuck with just one notion of equality for methods such as indexOf and contains.This is very, very annoying. In this example, we are looking for first occurrence of string “brian” in the given list.