ArrayList is a dynamic data structure in which you can add or remove any number of elements and those elements are stored in ordered sequence. It may also contain duplicate values.<\/p>\n
ArrayList are the implementations of List<\/a> interface. The package you required to import the ArrayList is import java.util.ArrayList;<\/strong><\/p>\n Important Note: <\/strong><\/span>In ArrayList, the items to be added are only of object<\/a> type. No primitive data types<\/a> (i.e. int, char etc) are allowed to insert in ArrayList.<\/p>\n Its very easy to use ArrayList, below is the syntax<\/a> to declare it:<\/p>\n String ArrayList Declaration:<\/strong><\/p>\n By using this syntax, an ArrayList is created which you can use to store characters. Here arrayListDemo is the name of this particular ArrayList.<\/p>\n ArrayList is a subclass of AbstractList<\/strong> class and it implements List<\/a> Interface.<\/strong> It has various methods that are defined and inherited from its parent class. Below is the list of those methods with example:<\/p>\n 1. boolean add(Object o):<\/strong><\/span><\/p>\n The Example program of this boolean add(Object o) method is as:<\/p>\n Output:<\/strong><\/p>\n 2. void clear():<\/strong><\/span><\/p>\n This method remove all the elements of the arraylist.<\/p>\n Below the example program clear() method shows the working of this method:<\/p>\n Output:<\/strong><\/p>\n 3. Object clone():<\/strong><\/span><\/p>\n This method returns the exact same copy of the arraylist object.<\/p>\n Below example helps us to understand this method easily:<\/p>\n Output:\u00a0<\/strong><\/p>\n 4. boolean contains(Object element):<\/strong><\/span><\/p>\n This method returns true if the calling ArrayList object contains the specific element as given in the argument list, otherwise it returns false.<\/p>\n Below is the example program of boolean contains(Object element) method is as:<\/p>\n Output:<\/strong><\/p>\n Read: List Of All ArrayList Methods<\/a><\/p>\n Example 1: ArrayList of Pre Definded Data types:<\/strong><\/span><\/p>\n Let us discuss ArrayList with the help of program, In this program we have created two objects that store predefined data types that are of Integer and String type, following program is divided into 3 steps that are discussed below:<\/p>\n Output:<\/strong><\/span><\/p>\n Explanation of Example:<\/strong><\/span><\/p>\n Example 2: ArrayList Of User-Defined Objects:<\/span><\/strong><\/p>\n We have discussed ArrayList example with Pre Defined Data types like Integer and String types, now let us discuss Arraylist of User Defined Class.<\/p>\n Now, Let us take a Class Student that has two properties its Name and Age. What we will do is, we will create different student objects and store them in the ArrayList as shown in the following program.<\/p>\n Creating the main class ArrayListDemo:<\/p>\n Output:<\/strong><\/span><\/p>\n Description:<\/strong><\/span><\/p>\n Another important thing about ArrayList is when to use it or when to use simple Array<\/a>? Now as you know ArrayList is dynamic in nature which means you can add or delete the elements with no fixed lower limit and upper limit. So in those situation where you are not sure about the number of elements you should use ArrayList. And where you are clear with the exact size of elements you can use Array. This is because array is fixed in size after its declaration\u00a0and\u00a0ArrayList is resizable in nature.<\/p>\n","protected":false},"excerpt":{"rendered":" ArrayList is a dynamic data structure in which you can add or remove any number of elements and those elements are stored in ordered sequence. It may also contain duplicate values. ArrayList are the implementations of List interface. The package you required to import the ArrayList is import java.util.ArrayList; Important Note: In ArrayList, the items … Continue reading ArrayList Tutorial With Examples In JAVA<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"home.php","meta":{"footnotes":""},"class_list":["post-450","page","type-page","status-publish","hentry"],"psp_head":"
\nSyntax of ArrayList:<\/strong><\/span><\/h4>\n
ArrayList arrayListDemo = new ArrayListDemo();<\/pre>\n
ArrayList<String> arrayListDemo = new ArrayListDemo<String>();<\/pre>\n
\nArrayList Methods:<\/strong><\/h4>\n
\n
import java.util.ArrayList;\r\n\r\npublic class ArrayListMethods {\r\n\r\npublic static void main(String[] args) {\r\n\u00a0\u00a0 \u00a0\r\n\u00a0\u00a0 \u00a0\/\/Integer ArrayList\r\nArrayList<Integer> aList = new ArrayList<Integer>();\r\n\r\naList.add(5);\r\naList.add(11);\r\naList.add(17);\r\n\r\nSystem.out.println(\"Integer Number Added in ArrayList= \" + aList);\r\n\r\n\/\/String ArrayList\r\nArrayList<String> sList = new ArrayList<String>();\r\n\r\nsList.add(\"Learning\");\r\nsList.add(\"JAVA\");\r\n\r\nSystem.out.println(\"String Added in ArrayList= \"+ sList);\r\n\r\n\r\n}\r\n\r\n}<\/pre>\nInteger Number Added in ArrayList= [5, 11, 17]\r\nString Added in ArrayList= [Learning, JAVA]\r\n<\/pre>\n
import java.util.ArrayList;\r\n\r\npublic class ArrayListMethods {\r\n\r\n\u00a0\u00a0 \u00a0public static void main(String args[]) {\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0ArrayList<Integer> aList = new ArrayList<Integer>();\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ use add() method to add elements in the list\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0aList.add(1);\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0aList.add(2);\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0aList.add(3);\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ let us print all the elements available in aList\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0System.out.println(\"Printing aList items before using clear method= \"+aList);\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0System.out.println(\"Printing size of aList1= \" + aList.size());\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/using clear method\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0aList.clear();\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0System.out.println(\"Printing aList element after using clear method= \"+aList);\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0System.out.println(\"size of aList1 after clear() method= \" + aList.size());\r\n\r\n\u00a0\u00a0 \u00a0}\r\n}<\/pre>\nPrinting aList items before using clear method= [1, 2, 3]\r\nPrinting size of aList1= 3\r\nPrinting aList element after using clear method= []\r\nsize of aList1 after clear() method= 0<\/pre>\n
import java.util.ArrayList;\r\n\r\npublic class ArrayListMethods {\r\n\u00a0\u00a0 \u00a0public static void main(String args[]) {\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0ArrayList<String> aList1 = new ArrayList<String>();\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ use add() method to add elements in the list\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0aList1.add(\"A\");\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0aList1.add(\"B\");\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0aList1.add(\"C\");\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0aList1.add(\"D\");\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/Using clone() method to copy aList1 into a new aListCopy Arraylist\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0ArrayList<String> aListCopy = (ArrayList<String>) aList1.clone();\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0System.out.println(\"aListCopy elements copied from aList1= \"+aListCopy);\r\n\r\n\u00a0\u00a0 \u00a0}\r\n}<\/pre>\naListCopy elements copied from aList1= [A, B, C, D]<\/pre>\n
import java.util.ArrayList;\r\n\r\npublic class ArrayListMethods {\r\n\r\n\u00a0\u00a0 \u00a0public static void main(String args[]) {\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0ArrayList<Integer> aList = new ArrayList<Integer>();\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ use add() method to add elements in the list\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0aList.add(7);\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0aList.add(2);\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0aList.add(9);\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/Checking contains method\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0boolean flag1 =\u00a0 aList.contains(2);\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0if (flag1 == true) {\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0System.out.println(\"aList contains element 2\");\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0}else{\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0System.out.println(\"aList doesn't contains element 2\");\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0}\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0boolean flag2 = aList.contains(5);\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0if (flag2 == true) {\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0System.out.println(\"aList contains element 5\");\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0} else{\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0System.out.println(\"aList doesn't contains element 5\");\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0}\r\n\r\n\r\n\u00a0\u00a0 \u00a0}\r\n\r\n}<\/pre>\naList contains element 2\r\naList doesn't contains element 5<\/pre>\n
\nArrayList Example In Java:<\/strong><\/h4>\n
import java.util.*; \r\n\r\n\r\npublic class ArrayListDemo{ \r\n \r\n public static void main(String args[]){ \r\n \r\n \/\/Step 1: Creating Objects of ArrayList\r\n ArrayList<String> arraylist1= new ArrayList<String>();\r\n ArrayList<Integer> arraylist2= new ArrayList<Integer>();\r\n\r\n \/\/Step 2: Adding Values \r\n arraylist1.add(\"This\");\r\n arraylist1.add(\"is\");\r\n arraylist1.add(\"String\");\r\n arraylist1.add(\"arraylist\");\r\n \r\n arraylist2.add(1);\r\n arraylist2.add(2);\r\n arraylist2.add(3);\r\n arraylist2.add(4);\r\n \r\n \/\/Step 3: Displaying all the values\r\n System.out.println(\"String ArrayList : \" +arraylist1);\r\n System.out.println(\"Integer ArrayList : \" +arraylist2);\r\n } \r\n}<\/pre>\nString ArrayList : [This, is, String, arraylist]\r\nInteger ArrayList : [1, 2, 3, 4]<\/pre>\n
\n
import java.util.*;\r\n\r\n\/\/Step 1: Created a Class that have values name and age\r\n\r\nclass Student{\r\nprivate int age;\r\nprivate String name;\r\n\r\n\/\/Step 2: Creating Constructor of Student class\r\npublic Student( String name, int age) {\r\nthis.age = age;\r\nthis.name = name;\r\n}\r\n\r\n\/\/Step 3: Getting and Setting the values\r\npublic int getAge() {\r\nreturn age;\r\n}\r\n\r\npublic void setAge(int age) {\r\nthis.age = age;\r\n}\r\npublic String getName() {\r\nreturn name;\r\n}\r\npublic void setName(String name) {\r\nthis.name = name;\r\n}\r\n\r\n\/\/Step 4: Gives meaning to the object\r\n\r\n@Override\r\n\r\npublic String toString() {\r\n\r\nreturn \"Student [name=\" + name + \", age=\" + age + \"]\";\r\n\r\n}\r\n}<\/pre>\nimport java.util.*;\r\n\/\/Step 5: Creating the main class\r\n\r\npublic class ArrayListDemo{\r\n\r\npublic static void main(String args[]){\r\n\r\n\/\/Step 6: Creating objects of Student class\r\n\r\nStudent student1= new Student(\"Vikas\" , 24);\r\nStudent student2= new Student(\"Arun\" , 23);\r\nStudent student3= new Student(\"Rahul\" , 25);\r\n\r\n\r\n\/\/Step 7: Creating an object of ArrayList and adding Student objects\r\n\r\nArrayList<Student> arrayStudent = new ArrayList<Student>();\r\n\r\narrayStudent.add(student1);\r\narrayStudent.add(student2);\r\narrayStudent.add(student3);\r\n\r\n\/\/Step 8: Displaying the values\r\n\r\nfor(Student student: arrayStudent){\r\n\r\nSystem.out.println(student);\r\n}\r\n}\r\n}\r\n\r\n<\/pre>\nStudent [name=Vikas, age=24]\r\nStudent [name=Arun, age=23]\r\nStudent [name=Rahul, age=25]\r\n\r\n<\/pre>\n
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\nImportance of ArrayList:<\/strong><\/span><\/h4>\n
\n
\nQuick Revision Points Of ArrayList:<\/strong><\/h4>\n
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\nArrayList Vs Array: Which To Use When:<\/strong><\/h4>\n