How to Implement Dynamic Arrays in Java for Changing Sizes and Values

How can I create a dynamic integer array in Java that allows for changing sizes and values throughout my program's execution?

// Example of using ArrayList for dynamic arrays in Java
import java.util.ArrayList;

public class DynamicArrayExample {
    public static void main(String[] args) {
        // Create a dynamic array using ArrayList
        ArrayList<Integer> dynamicArray = new ArrayList<>();

        // Adding elements to the dynamic array
        dynamicArray.add(10);
        dynamicArray.add(20);
        dynamicArray.add(30);

        // Display current values
        System.out.println("Dynamic Array: " + dynamicArray);

        // Modifying an element
        dynamicArray.set(1, 25); // Changes 20 to 25

        // Removing an element
        dynamicArray.remove(0); // Removes the first element (10)

        // Display modified array
        System.out.println("Modified Dynamic Array: " + dynamicArray);
    }
}

In Java, conventional arrays have a fixed size. To create an integer array that can dynamically change size and values, you should use collections such as the ArrayList class. ArrayLists provide a flexible structure that allows adding, removing, and modifying elements efficiently.

import java.util.ArrayList;

public class DynamicArrayExample {
    public static void main(String[] args) {
        ArrayList<Integer> dynamicArray = new ArrayList<>();
        dynamicArray.add(10);
        dynamicArray.add(20);
        dynamicArray.add(30);
        System.out.println(dynamicArray);
        dynamicArray.set(1, 25);
        dynamicArray.remove(0);
        System.out.println(dynamicArray);
    }
}

Causes

• Java arrays are of fixed length once created.
• The need for a data structure that allows resizing during runtime.

Solutions

• Use the ArrayList class from the Java Collections Framework which allows dynamic sizing.
• Instantiate an ArrayList and use methods like add(), remove(), and set() to manipulate the elements.
• You can convert an ArrayList back to an array if needed using the toArray() method.

Mistake: Not importing the correct Java packages for ArrayList usage.

Solution: Ensure that you include 'import java.util.ArrayList;' at the top of your Java file.

Mistake: Assuming ArrayLists can only store primitive data types directly.

Solution: Use wrapper classes like Integer for int, Double for double, and so on when adding primitive values to an ArrayList.