ArrayList class in Java is basically a resizable array i.e. it can grow and shrink in size dynamically according to the values that we add or remove to/from it. It is present in java.util package.
We will discuss if an ArrayList can contain multiple references to the same object in Java.
The ArrayList in java does not provide the checks for duplicate references to the same object. Therefore, we can insert the same object or reference to a single object as many times as we want. If we wish we can check if an element already exists in ArrayList or not with the help of the contains() method.
Below is the code implementation of the above problem statement:
Java
// Java program to demonstrate some functionalities// of ArrayListimport java.util.ArrayList;class Employee{ private String name; private String designation; // Parameterized constructor for Employee class public Employee(String name, String designation) { this.name = name; this.designation = designation; } // Creating getters for Employee class public String getName() { return name; } public String getDesignation() { return designation; }}public class GFG { public static void main(String[] args) { // Creating Objects of Employee class Employee e1 = new Employee("Raj","Manager"); Employee e2 = new Employee("Simran", "CEO"); Employee e3 = new Employee("Anish", "CTO"); // Creating an ArrayList of Employee type ArrayList<Employee> employeeList= new ArrayList<>(); // Inserting the employee objects in the ArrayList employeeList.add(e1); employeeList.add(e2); employeeList.add(e3); // e1 will be inserted again as ArrayList can store multiple // reference to the same object employeeList.add(e1); // Checking if e2 already exists inside ArrayList // if it exists then we don't insert it again if(!employeeList.contains(e2)) employeeList.add(e2); // ArrayList after insertions: [e1, e2, e3, e1] // Iterating the ArrayList with the help of Enhanced for loop for(Employee employee: employeeList){ System.out.println(employee.getName() + " is a " + employee.getDesignation()); } }} |
Output
Raj is a Manager Simran is a CEO Anish is a CTO Raj is a Manager
