ArrayList en Java

ArrayList es parte del marco de la colección y está presente en el paquete java.util. Nos proporciona arreglos dinámicos en Java. Sin embargo, puede ser más lento que las arrays estándar, pero puede ser útil en programas donde se necesita mucha manipulación en la array. Esta clase se encuentra en el paquete  java.util .

// Java program to demonstrate the 
// working of ArrayList in Java 
  
import java.io.*; 
import java.util.*; 
  
class ArrayListExample { 
    public static void main(String[] args) 
    { 
        // Size of the 
        // ArrayList 
        int n = 5; 
  
        // Declaring the ArrayList with 
        // initial size n 
        ArrayList<Integer> arrli 
            = new ArrayList<Integer>(n); 
  
        // Appending new elements at 
        // the end of the list 
        for (int i = 1; i <= n; i++) 
            arrli.add(i); 
  
        // Printing elements 
        System.out.println(arrli); 
  
        // Remove element at index 3 
        arrli.remove(3); 
  
        // Displaying the ArrayList 
        // after deletion 
        System.out.println(arrli); 
  
        // Printing elements one by one 
        for (int i = 0; i < arrli.size(); i++) 
            System.out.print(arrli.get(i) + " "); 
    } 
} 

// Java Program to Add elements to An ArrayList
  
// Importing all utility classes
import java.util.*;
  
// Main class
class GFG {
  
    // Main driver method
    public static void main(String args[])
    {
        // Creating an Array of string type
        ArrayList<String> al = new ArrayList<>();
  
        // Adding elements to ArrayList
        // Custom inputs
        al.add("Geeks");
        al.add("Geeks");
  
        // Here we are mentioning the index
        // at which it is to be added
        al.add(1, "For");
  
        // Printing all the elements in an ArrayList
        System.out.println(al);
    }
}

// Java Program to Change elements in ArrayList
  
// Importing all utility classes
import java.util.*;
  
// main class
class GFG {
  
    // Main driver method
    public static void main(String args[])
    {
        // Creating an Arraylist object of string type
        ArrayList<String> al = new ArrayList<>();
  
        // Adding elements to Arraylist
        // Custom input elements
        al.add("Geeks");
        al.add("Geeks");
  
        // Adding specifying the index to be added
        al.add(1, "Geeks");
  
        // Printing the Arraylist elements
        System.out.println("Initial ArrayList " + al);
  
        // Setting element at 1st index
        al.set(1, "For");
  
        //  Printing the updated Arraylist
        System.out.println("Updated ArrayList " + al);
    }
}

// Java program to Remove Elements in ArrayList
  
// Importing all utility classes
import java.util.*;
  
// Main class
class GFG {
  
    // Main driver method
    public static void main(String args[])
    {
        // Creating an object of arraylist class
        ArrayList<String> al = new ArrayList<>();
  
        // Adding elements to ArrayList
        // Custom addition
        al.add("Geeks");
        al.add("Geeks");
        // Adding element at specific index
        al.add(1, "For");
  
        // Printing all elements of ArrayList
        System.out.println("Initial ArrayList " + al);
  
        // Removing element from above ArrayList
        al.remove(1);
  
        // Printing the updated Arraylist elements
        System.out.println("After the Index Removal " + al);
  
        // Removing this word element in ArrayList
        al.remove("Geeks");
  
        // Now printing updated ArrayList
        System.out.println("After the Object Removal "
                           + al);
    }
}

// Java program to Iterate the elements
// in an ArrayList
  
// Importing all utility classes
import java.util.*;
  
// Main class
class GFG {
  
    // Main driver method
    public static void main(String args[])
    {
        // Creating an Arraylist of string type
        ArrayList<String> al = new ArrayList<>();
  
        // Adding elements to ArrayList
        //  using standard add() method
        al.add("Geeks");
        al.add("Geeks");
        al.add(1, "For");
  
        // Using the Get method and the
        // for loop
        for (int i = 0; i < al.size(); i++) {
  
            System.out.print(al.get(i) + " ");
        }
  
        System.out.println();
  
        // Using the for each loop
        for (String str : al)
            System.out.print(str + " ");
    }
}