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A class attribute is an attribute of the class rather than an attribute of an instance of the class.In the code below class_var is a class attribute, and i_var is an instance attribute: All instances of the class have access to class_var, which can also be accessed as a property of the class itself −Exampleclass MyClass (object): class_var = 2 def __init__(self, i_var): self.i_var = i_var foo = MyClass(3) baz = MyClass(4) print (foo.class_var, foo.i_var) print (baz.class_var, baz.i_var)OutputThis gives the output(2, 3) (2, 4)
The add(int index, E element) method of the java.util.ArrayList class inserts the specified element E at the specified position in this list. It shifts the element currently at that position (if any) and any subsequent elements to the right (will add one to their indices).Exampleimport java.util.ArrayList; public class ArrayListDemo { public static void main(String[] args) { ArrayList arrlist = new ArrayList(5); arrlist.add(15); arrlist.add(22); arrlist.add(30); arrlist.add(40); arrlist.add(2,25); for (Integer number : arrlist) { System.out.println("Number = " + number); } } }OutputNumber = 15 Number = 22 Number = 25 Number = 30 Number = 40
The removeRange() method of the ArrayList class removes all of the elements from this List whose index is between fromIndex and toIndex.Exampleimport java.util.*; public class ArrayListDemo extends ArrayList{ public static void main(String[] args) { ArrayListDemo arrlist = new ArrayListDemo(); arrlist.add(10); arrlist.add(12); arrlist.add(31); System.out.println("The list:" + arrlist); arrlist.removeRange(0,2); System.out.println("The list after using removeRange:" + arrlist); } }OutputThe list:[10, 12, 31] The list after using removeRange:[31]
The set() method of the ArrayList class replaces the element at the specified position in this list with the specified element.Exampleimport java.util.ArrayList; public class Sample { public static void main(String args[]) { ArrayList al = new ArrayList(); System.out.println("Initial size of al: " + al.size()); al.add("C"); al.add("A"); al.add("E"); al.add(1, "A2"); System.out.println("Size of al after additions: " + al.size()); System.out.println("Contents of al: " + al); System.out.println("Size of al after deletions: " + al.size()); ... Read More
The trimToSize() method of the java.util.ArrayList class trims the capacity of this ArrayList instance to be the list's current size. An application can use this operation to minimize the storage of an ArrayList instance.Exampleimport java.util.ArrayList; public class ArrayListDemo { public static void main(String args[]) { ArrayList arrlist = new ArrayList(5); arrlist.add(35); arrlist.add(20); arrlist.add(25); arrlist.trimToSize(); for (Integer number : arrlist) { System.out.println("Number = " + number); } } }OutputNumber = 35 Number = 20 Number = 25
The lastIndexOf(Object) method of the class java.util.ArrayList returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.Exampleimport java.util.ArrayList; public class ArrayListDemo { public static void main(String[] args) { ArrayList arrlist = new ArrayList(5); arrlist.add("G"); arrlist.add("E"); arrlist.add("F"); arrlist.add("M"); arrlist.add("E"); System.out.println("Size of list: " + arrlist.size()); for (String value : arrlist) { System.out.println("Value = " + value); ... Read More
The indexOf(Object) method of the java.util.ArrayList class returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.Exampleimport java.util.ArrayList; public class ArrayListDemo { public static void main(String[] args) { ArrayList arrlist = new ArrayList(5); arrlist.add("G"); arrlist.add("E"); arrlist.add("F"); arrlist.add("M"); System.out.println("Size of list: " + arrlist.size()); for (String value : arrlist) { System.out.println("Value = " + value); } ... Read More
The get(int index) method of the java.util.ArrayList class returns the element at the specified position in this list.Exampleimport java.util.ArrayList; public class ArrayListDemo { public static void main(String[] args) { ArrayList arrlist = new ArrayList(5); arrlist.add(15); arrlist.add(22); arrlist.add(30); arrlist.add(40); for (Integer number : arrlist) { System.out.println("Number = " + number); } int retval=arrlist.get(3); System.out.println("Retrieved element is = " + retval); } }OutputNumber = 15 Number = 22 Number = 30 Number = 40 Retrieved element is = 40
The isEmpty() method of the class java.util.ArrayList returns true if this list contains no elements.Exampleimport java.util.ArrayList; public class ArrayListDemo { public static void main(String[] args) { ArrayList arrlist = new ArrayList(5); arrlist.add(25); arrlist.add(10); arrlist.add(20); arrlist.add(35); boolean retval = arrlist.isEmpty(); if (retval == true) { System.out.println("list is empty"); } else { System.out.println("list is not empty"); } for (Integer number : arrlist) { System.out.println("Number = " + number); } } }Outputlist is not empty Number = 25 Number = 10 Number = 20 Number = 35
The size() method of the class java.util.ArrayList returns the number of elements in this list i.e. the size of the list.Exampleimport java.util.ArrayList; public class ArrayListDemo { public static void main(String[] args) { ArrayList arrlist = new ArrayList(5); arrlist.add(15); arrlist.add(20); arrlist.add(25); arrlist.add(22); for (Integer number : arrlist) { System.out.println("Number = " + number); } int retval = arrlist.size(); System.out.println("Size of list = " + retval); } }OutputNumber = 15 Number = 20 Number = 25 Number = 22 Size of list = 4