Java Collections - ArrayList Constructors Examples

package com.logicbig.example.arraylist;

import java.util.*;

public class ArrayListExample {

    public static void main(String... args) {
        // Default constructor with initial capacity of 10
        ArrayList<String> list1 = new ArrayList<>();
        list1.add("Apple");
        list1.add("Banana");
        System.out.println("List created with default constructor: " + list1);
    }
}

package com.logicbig.example.arraylist;

import java.util.*;

public class ArrayListExample2 {

    public static void main(String... args) {
        // Creating empty ArrayList for integers
        ArrayList<Integer> numbers = new ArrayList<>();
        numbers.add(10);
        numbers.add(20);
        System.out.println("Integer list size: " + numbers.size());
    }
}

package com.logicbig.example.arraylist;

import java.util.*;

public class ArrayListExample3 {

    public static void main(String... args) {
        // Using default constructor with type inference
        ArrayList<Double> prices = new ArrayList<>();
        prices.add(9.99);
        prices.add(19.99);
        System.out.println("Prices: " + prices);
    }
}

package com.logicbig.example.arraylist;

import java.util.*;

public class ArrayListExample4 {

    public static void main(String... args) {
        // Pre-allocate capacity for 1000 elements to avoid rehashing
        ArrayList<String> largeList = new ArrayList<>(1000);
        for(int i = 0; i < 1000; i++) {
            largeList.add("Item" + i);
        }
        System.out.println("Large list size: " + largeList.size());
    }
}

package com.logicbig.example.arraylist;

import java.util.*;

public class ArrayListExample5 {

    public static void main(String... args) {
        // Create ArrayList with initial capacity of 0
        ArrayList<String> emptyList = new ArrayList<>(0);
        System.out.println("Empty list size: " + emptyList.size());
        emptyList.add("First"); // Will resize automatically
        System.out.println("After adding element: " + emptyList.size());
    }
}

package com.logicbig.example.arraylist;

import java.util.*;

public class ArrayListExample7 {

    public static void main(String... args) {
        // Create ArrayList from another collection
        List<String> names = Arrays.asList("Alice", "Bob", "Charlie");
        ArrayList<String> nameList = new ArrayList<>(names);
        System.out.println("List created from collection: " + nameList);
    }
}

package com.logicbig.example.arraylist;

import java.util.*;

public class ArrayListExample8 {

    public static void main(String... args) {
        // Copy ArrayList from another ArrayList
        ArrayList<Integer> original = new ArrayList<>();
        original.add(1);
        original.add(2);
        original.add(3);
        ArrayList<Integer> copy = new ArrayList<>(original);
        copy.add(4);
        System.out.println("Original: " + original + ", Copy: " + copy);
    }
}

package com.logicbig.example.arraylist;

import java.util.*;

public class ArrayListExample9 {

    public static void main(String... args) {
        // Create ArrayList from HashSet (remove duplicates)
        Set<String> set = new HashSet<>(Arrays.asList("A", "B", "A"));
        ArrayList<String> listFromSet = new ArrayList<>(set);
        System.out.println("List from set (duplicates removed): " + listFromSet);
        System.out.println("Size: " + listFromSet.size());
    }
}