Chapter 7: Problem 26

How do you add items to an ArrayList object?

Short Answer

Expert verified

Answer: To add items to an ArrayList object in Java, follow these steps: 1. Import the ArrayList class using the code `import java.util.ArrayList;`. 2. Declare and instantiate an ArrayList object, specifying the type of elements it will handle, for example: `ArrayList myArrayList = new ArrayList();`. 3. Add elements using the add() method, passing the element as an argument, like this: `myArrayList.add("Hello");`. 4. To add elements at a specific index, use the overloaded add() method with the index and the element as arguments, for example: `myArrayList.add(1, "World");`. 5. Verify that the elements have been added by printing the contents of the ArrayList using the toString() method: `System.out.println("ArrayList contents: " + myArrayList.toString());`.

Step by step solution

Import the ArrayList class

The first step is to import the java.util.ArrayList class, which provides the functionality for working with ArrayLists. ```java import java.util.ArrayList; ```

Declare and instantiate an ArrayList object

Next, declare an ArrayList object and instantiate it. To do this, you will need to use the "new" keyword and specify the type of elements the ArrayList will handle. In this example, we will be creating an ArrayList of strings. ```java ArrayList myArrayList = new ArrayList(); ```

Add elements using the add() method

To add elements to the ArrayList, we will use the add() method. The add() method accepts an argument, which is the element being added to the ArrayList. To add a string "Hello" to our ArrayList, use the following code: ```java myArrayList.add("Hello"); ```

Add elements at a specific index

You can also add elements to the ArrayList at a specific index using an overloaded version of the add() method. This method accepts two arguments, the first being the index at which the element should be inserted, and the second being the element itself. To add a string "World" at index 1, use the following code: ```java myArrayList.add(1, "World"); ```

Verify elements have been added

After adding the elements, you can check the contents of the ArrayList by using the toString() method to output the elements. Use the following code: ```java System.out.println("ArrayList contents: " + myArrayList.toString()); ``` This will output: ``` ArrayList contents: [Hello, World] ```

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How do you add items to an ArrayList object?

Short Answer

Step by step solution

Import the ArrayList class

Declare and instantiate an ArrayList object

Add elements using the add() method

Add elements at a specific index

Verify elements have been added

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