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Add string to list java

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The Java list interface, Java.util.list, represents an orderly sequence of objects. The elements contained in a Java list can be inserted, accessible, ironed and removed according to the order in which they appear internally in the Java list. The sorting of the elements is why this data structure is called a list. Each element in a Java list has an index. The first element in the list has the index 0, the second element index 1 etc. The index means "how many elements away from the beginning of the list". The first element is therefore 0 elements away from the beginning of the list - because it is at the beginning of the list. You can add any Java object to a list. If the list is not typed, using Java Generics, you can also mix objects of different types (classes) in the same list. The mixing of objects of different types in the same list is often done in practice, however. The Java list interface is a standard Java interface, and is a subtype of the Java collection interface, which means list inherits from the collection. Java Tutorial Video List If you prefer to watch a video instead of reading the text, here is a video version of this Java list tutorial: list vs. Set the Java list and Java Set interfaces are quite similar as they are both a collection of elements. However, there are some significant differences. These differences are reflected in the methods that the list and settings set are offer. The first difference between the Java list and the Java set interface is that the same element can happen more than once in a Java list. This is different from a Java set where each item can only occur once. The second difference between a Java list and a Java set interface is that the elements in a list have an order, and the elements can be eleterized in that order. A Java set does not promise the order of the elements held internally. List implementations are a collection subtype all methods in the collection interface are also available in the list interface. Because the list is a necessary interface to instantiate a concrete interface implementation to use it. You can choose from the following list implementations in the Java collection API: java.util.arraylist java.util.linkedlist java.util.vector java.util.stack of these implementations, the Arraylist is the most commonly used. There are also implementations of concomitant lists in the Java.util.Concurrent package. These list implementations are explained more detailed in my Java.util.Concurrent tutorial. Creating a list You create a list instance by creating an instance of one of the classes that implements the list interface. Here are some examples of how to create a list instance: list list = new arraylist (); Listb list = new liation (); Listc list = new carrier (); ListD list = new stack (); Remember, very often you will use the Arraylist class, but there may be cases in which the use of one of the other implementations could make sense. General lists By default You can enter any object in a list, but from Java 5, Generics Generics allows you to limit the types of objects you can enter in a list. Here is one example: List List = New Arraylist (); This list can now only have myobject instances inserted in it. You can then access and harbor its elements without launching them. Here's how it appears: List List = New Arraylist (); list.add (new myobject ("first myobject"); MyObject MyObject = List.get (0); For (MyObject Anobject: List) {// Do something to Anobject ...} Without generic the example above would be taken as this: List list = new Arraylist (); // No list specified of generic type.Addi (new MyObject ("First MyObject MyObject = (MyObject) List.get.get (0); // CAST required for (Anobject object: List) {// Cast Bests MyObject theyyyObject = (MyObject) Anobject; // Rentally at Anobject ...} Note how it is necessary to launch MyObject instances recovered from the MyObject list. Without a generic type set set Variable declaration list The Java compiler knows only the list contains instances of objects. Therefore, it is necessary to throw them to the concrete class (or interface) of which you know the object from. It is a good practice to specify a generic type for your list variables whenever you can. It helps you avoid inserting the types of wrong objects in the list. Allows you to retrieve objects from the list without having to throw them their real type. And - helps the reader of your code to see what kind of objects that the list should contain. You should only omit a generic type if you have excellent reasons to do it. Throughout the rest of this Java list tutorial I will use the most as possible examples of generic lists. For more information on Java Generics, consult the Java Generics Tutorial. Enter items in a Java list you enter elements (objects) in a Java list using its ADD () method. Here is an example of adding elements to a Java list using the ADD () method: list = New Arraylist (); lisla.add ("element 1"); lisla.add ("element 2"); lisla.add ("element 3"); The first three additions () calls add a string instance at the end of the list. Insert NULL values you can actually enter NULL values in a Java list. Here is an example of inserting a null value in a Java list: Item Item = NULL; List List = New Arraylist (); list.add (element); Enter elements in specific index you can enter an item to a Java list in a specific index. The list interface has a version of the ADD () method that accepts an index as the first parameter and the item to be inserted as the second parameter. Here is an example of inserting an element to index 0 in a Java list: List. Address (0, "Element 4"); If the list is already the content of elements, these elements will now be pushed more in the internal sequence of the list. The element that had the index 0 before the new element has been inserted to index 0, will be pressed on index 1, etc. Enter all items from one list to another You can add all items from a Java list to another list. You do it using the LIST AddTall () method. The resulting list is the union of the two lists. Here is an example of adding all elements from a list to another: Listsource list = New Arraylist (); LISTSOURCE.ADD ("123"); LISTSOURCE.ADD ("456"); Listdest list = New Arraylist (); LISTDEST.ADDALL (LISTSOURCE); This example adds all elements from ListSource to Listdest. The addall () method takes a collection as a parameter, so you can pass a list or java set as a parameter. In other words, you can add all items from a list or set to a list with adddall (). Get items from a Java list You can get the items from a Java list using the index of the elements. You can do it using the Get (Int Index) method. Here is an example of access to the elements of a Java list using the indexes of the element: List List = New Arraylist (); lisla.add ("element 0"); lisla.add ("element 1"); lisla.add ("element 2"); // access via index string element0 = lisa.get (0); String element1 = lisa.get (1); String element3 = lisa.get (2); It is also possible to overreach the elements of a Java list in the order in which they are stored internally. You show you how to do it further into this Java list tutorial. Find items in a list you can find items in a Java list using one of these two methods: the indexof () method finds the first occurrence index in the list of the indicated element. Here is an example by finding the index of two elements in a Java list: list list = new arraylist (); String element1 = "element 1"; String element2 = "element 2"; (element1); list.add (element2); INT INDEX1 = LIST.INDEXOF (element1); INT INDEX2 = LIST.INDEXOF (element2); System.out.println ("index1 =" + index1); System.out.println ("index2 =" + index2); The execution of this code will behave in this output: index1 = 0 index2 = 1 find the last occurrence of an element in a list Method finds the index of the last occurrence in the list of a certain element. Here is an example that shows how to find the index of the last occurrence of a given element in a Java list: list = New Arraylist (); String element1 = "element 1"; String element2 = "element 2"; list.add (element1); list.add (element2); list.add (element1); int lastindex = list.lastindexof (element1); System.out.println ("Lastindex =" + Lastindex); The output printed by the execution of the previous Java example will be: Lastindex = 2 The element element 1 occurs twice in the list. The index of the last occurrence is 2. Check if the list contains item you can check if a Java list contains a certain element using the list contains () method. Here is an example of checking if a Java list contains an element using the method contains (): list list = new arraylist (); String element1 = "element 1"; list.add (element1); Boolean ConvelingElement = List.Contains ("Element 1"); System.out.println (containing); The output to be performed this example of a Java list will be true ... because the list actually contains the element. To determine if the list contains the item, the list will glorize its elements internally and will compare each item on the object passed as a parameter. The comparison uses the Java method is the same as the element to check if the item is the same as the parameter. Since it is possible to add null values to a list, it is actually possible to check if the list contains a null value. Here's how you control if a list contains a null value: list.add (null); Container = list.contains (null); System.out.println (containing); Obviously, if the input parameter for contains () is null, the method contains () will not use the EQUALS () method to compare with each item, but rather use the operator ==. Remove items from a Java list you can remove items from a Java list via these two methods: Remove Remove (Int Index) remove (object item) removes that element in the list, if it is present. All subsequent elements in the list are then moved to the list. Their index therefore decreases by 1. Here is an example of removing an element from a Java list based on the element: List List = New Arraylist (); String element = "first element"; list.add (element); list.Remove; This example first adds an element to a list and then removes again. The Remove list method removes the element in the specified index. All subsequent elements in the list are then moved to the list. Their index therefore decreases by 1. Here is an example of removing an element from a Java list for its index: List List = New Arraylist (); list.add ("element 0"); list.add ("element 1"); list.add ("element 2"); list.Remove (0); After executing the Java sample code, the list would contain Elements Elements String Elements 1 and element 2 to index 0 and 1. The first element (element 0) has been removed from the list. Remove all items from a Java list The Java list interface contains a clear () method that removes all the elements from the list when called. The removal of all elements from a list is also postponed as a list of a list. Here is a simple example of removing all elements from a list (compensation) with the Clear () method: list = New Arraylist (); list.add ("Object 1"); list.add (object 2 "); //etc. list.clear (); First of all, a new list is created. Second, two elements are added to the list. Thirdly, the clear method () is called. After the light method () has been called, the list will be completely empty. All items from a list in another The Java list interface has a method called retinalall () that is able to contain all the elements from a list that is also present in another list. In other words, the storage method () removes all the elements from the destination list that are not in the other list. The resulting list is the intersection of the two lists. Here is a Java example to call the list list Method: List List = New Arraylist (); LIST ALLUDIST = NEW ARRAYLIST (); String element1 = "element 1"; String element2 = "element 2"; String element3 = "of element 3"; String element4 = "element 4"; list.add (element1); list.add (element2); List.add (element3); OTHERLIST.ADD (element1); OTHERLIST.ADD (element3); OTHERLIST.ADD (element4); List.retainAll (AltraList); First, two lists are created. Secondly, 3 elements are added to the list and 3 elements are added to the otherist. Thirdly, the retainall () method is called in the list, passing the otherist as a parameter. After List.retainAll (AltraLista) has finished the execution, the list will only be the elements that were both present in the list and otherist before retinalall () was called. More particularly, which is Element1 and Element3. List Size You can get the number of items in the list by calling the Size () method. Here is an example: List List = New Arraylist (); list.add ("Object 1"); list.add (object 2 "); INT SIZE = LIST.SIZE (); Secondary list of LIST interface The Java list has a method called underlinth () which can create a new list with a subset of the original list elements. The subway () method accepts 2 parameters: an initial and final index and index. The starting index is the index of the first element of the original list to be included in the subway. The final index is the last index of the subway, but the element at the last index is not included in the submenu. This is similar to how the substring Java String method works. Here is a Java example to create a secondary list of elements from another list using the subway method (): List List = New Arraylist (); list.add ("element 1"); list.add ("element 2"); List.add ("element 3"); List.add ("element 4"); List Sottoenco = List.Sublist (1, 3); After executing the list.SUBList (1.3) submission submission will contain index elements 1 and 2. remember, the original list has 4 elements with indexes from 0 to 3. List.Sublist (1.3) Call will include index 1, but excludes index 3, thus maintaining index elements 1 and 2. Convert list to Set You can convert a Java list for a set of Java with creating a new set and adding All items from the list to it. The set remove all the duplicates. So, the resulting set will control all the elements from the list, but only once. Here is an example of converting a Java list for a set: List List = New Arraylist (); list.add ("element 1"); list.add ("element 2"); List.add ("element 3"); List.add ("element 3"); Set set = new hashset (); set.Addall (list); Note that the list contains the String 3 twice. The set will only contain that string once. So, the resulting set will control strings element 1, element 2 and element 3. Convert array list you can convert a Java list into a Java array using the List Tarray () method. Here is an example of converting a Java list to a Java Array: List List = New Arraylist (); list.add ("element 1"); list.add ("element 2"); List.add ("element 3"); List.add ("element 3"); Object [] = List.toarray () objects; It is also possible to convert a list to a specific type array. Here is an example of converting a Java list to an array of a specific type: List list = New Arraylist (); list.add ("element 1"); list.add ("element 2"); List.add ("element 3"); List.add ("element 3"); String [] object1 = list.toarray (New String [0]); Note that even if you pass an array of size 1 toarray strings (), the return matrix will have all the elements in the list of it. It will have the same number of items like the list. Convert To List It is also possible to convert a Java list to an array. Here is an example of converting a Java array to a list: String [] values = new string [] {"one", "two", "three"}; List list = (List ) arrays.aslist (values); It is the arrays.aslist () method that converts the matrix to a list. Order list You can order a Java list using the collections Method Sort (). I have How it works in my Java Collections selection tutorial, but you will show you only a few ways to order a Java list in the following sections. Order list of comparable objects If the list contains objects that implement the comparable interface (java.lang. Comparable), objects can compare each other. In this case you can order the list like this: List = New Arraylist (); list.add ("C"); list.add ("B"); list.add ("A"); Collections.sort (list); The String Java class implements the comparable interface, you can order them in their natural order, using the method of sorting collections (). Order list using the comparator If the objects in the Java list do not implement the comparable interface or if you want to sort objects in another order than their comparison () Implementation, you need to use a comparator implementation (java.util.rupcomarator ). Here is an example of sorting a list of car objects using a comparator. Here is the first class of the car: public class cars {Public string brand; Public public string int nofdoors; Public car (Brand brand, string platesplate, int nofdoors) {this.brand = brand; This.numberplate = plastems; this.noofdoors = nofdoors; }} Here is the code that sorts a Java list of the objects above: list List = New Arraylist (); list.add (new car ("Volvo V40", "XYZ 201845", 5)); list.add (new car ("Citroen C1", "ABC 164521", 4)); list.add (new car ("Dodge Ram", "KLM 845990", 2)); Comparator Carbardcomparator = New Comparator () {@override Public int compare (car car1, car car2) {return car1.pareto (car2.); }} ;;; Collections.sort (list, carbardcomparator); Note the implementation of the comparator in the example above. This implementation compares only the field of the car object brand. You can create another implementation of the comparator that compares numerical plates, or even the number of doors in the cars. Note also that you can implement a comparator using a Lambda Java. Here is an example that sorts a list of auto objects using three different Java Lambda implementations of the comparator interface, each compares car instances from a different field: list List = new Arraylist (); list.add (new car ("Volvo V40", "XYZ 201845", 5)); list.add (new car ("Citroen C1", "ABC 164521", 4)); list.add (new car ("Dodge Ram", "KLM 845990", 2)); Comparator CarbRandComparatorlamda = (Car1, Car2) -> car1.pareto (car2.brand); Comparator CarnumberplatComparatorlamd = (Car1, Car2) -> car1.Pareto (car2.numberplate); Comparator carnoooooooorscomparatorlamd = (car1, car2) -> car1.noofdoors - car2.noofdoors; Collections.sort (list, carbardcomparatorlamd); Collections.sort (list, carnumberplatcomparatorlambda); Collections.sort (list, carnoovdoorscomparatorlambda); Ierated list You can isolate a Java list in different ways. The three most common ways are: Using an iterator that uses a loop for each one using a loop using the Java Stream API, will explain each of these methods of iterations of a Java list in the following sections. Iterato list using iterator The first way to iron a list is to use a java iterator. Here is an example of an Iterating list with an iterator: List = New Arraylist (); list.add ("First"); list.add ("second"); list.add ("third"); Iterator iterator = list.iterator (); WHILE (iterator.hasnext ()) {string Next = iterator.next (); } You get an iterator by calling the Iterator () method of the list interface. Once you get an iterator you can continue to call its Hasnext () method until false returns. Call Hasnext () is made Of a cycle while you can see. Within the cycle while the next iterator method () of the iterator interface is called to obtain the next element indicated by the iterator. If the list is typed using Java Generics you can save the object casting inside the loop while loop. Here is one example: List = New Arraylist (); (); list.add ("second"); list.add ("third"); Iterator iterator = list.iterator (); WHILE (iterator.hasnext ()) {string obj = iterator.next (); } Top list Using for-what cound The second way to endure a list is to use the added loop in Java 5 (also called "for each" cycle). Here is an example of Iterating a list using the loop per list: list list = new arraylist (); list.add ("First"); list.add ("second"); list.add ("third"); per (object element: list) {system.out.println (element); } The loop is performed once per list in the list. Inside the cycle each element is in turn linked to the Variable OBJ. If the list is typed (a generic list) you can change the type of variable within the loop cycle. Here iteration list is entered Example: List List = New Arraylist (); // Add elements to the list for (string element: list) {system.out.println (element); } Notice How the String list is typed. Therefore it is possible to set the type of variable within the string loop. IROTORY LIST Using the LOOP the third way to iterating a list is to use a standard for loops like this: list list = new arraylist (); list.add ("First"); list.add ("second"); list.add ("third"); for (int i = 0; ih List = New Arraylist (); list.add ("First"); list.add ("second"); list.add ("third"); for (int i = 0; ih {System.out.println (element);}); Call the Foreach () method will make the flow that will urge all the flow element internally and call the consumer passed as a parameter to the Foreach method () for each element in the flow. You can read more about the many different options available for element processing A list through the Java Stream API in my Java Stream API tutorials. More details in the Java Javadoc list there is a lot more than you can do with a Java list, but you will need to check Javadoc for more details. This text focused on the two most common operations: add / removing elements and interacting the elements. elements. elements.

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