Arrays

  • different data structures
  • primitive contains single data type
  • reference contains multiple data types
  • the element is the value in the array
  • the index is the position
int[] array = new int[10];
int[] array2 = {1, 2, 3, 4, 5};

Errors

  • accessing a value that doesn't not exist because it isn't in the bounds
  • when you initialize a single array but not the whole array

Traverse in Arrays

  • accessing the inside of an array
  • a loop or iteration can traverse</mark> an array</li> </ul> </div> </div> </div> 
    for (int i = 0; i < array.length; i++) {
    System.out.println(array[i]);
}

    Arrays can be configured through

    • .add
    • .get
    • .set
    • .sort
    • .clear

    The .add method adds an index to the array list and the .get calls the specific index number. The .set method sets the index to a new index. The .sort method sorts the indexes in a certain order and .clear will clear all the indexes in the array.

    import java.util.ArrayList;
import java.util.Collections;

public class Main {
    public static void main() {
        ArrayList<String> sports = new ArrayList<String>(); //Creates a new array
        sports.add("Football");
        sports.add("Basketball"); //adds different sports to the array
        sports.add("Soccer");
        sports.add("Baseball");
        sports.add("Tennis");
        System.out.println(sports); // prints the array

        System.out.println(" ");

        for (int i = 0; i < 5; i++) {
            System.out.println(sports.get(i)); // prints each array separately
        }

        System.out.println(" ");
        System.out.println("The size of the array is " + sports.size()); //prints the size of the array

        sports.set(3, "Golf"); // changes the 3 array to "Golf"
        System.out.println("The 3 array has been changed to " + sports.get(3));

        System.out.println(" ");

        Collections.sort(sports); //sorts the array in alphabetical order
        System.out.println("The array list is in alphabetical order:");
        for (String i : sports) {
            System.out.println(i);
        }

        System.out.println(" ");
        sports.clear(); //clears the array
        System.out.println("The array list is now empty and says:" + sports);
    }
}

Main.main();

    [Football, Basketball, Soccer, Baseball, Tennis]
 
Football
Basketball
Soccer
Baseball
Tennis
 
The size of the array is 5
The 3 array has been changed to Golf
 
The array list is in alphabetical order:
Basketball
Football
Golf
Soccer
Tennis
 
The array list is now empty and says:[]

    Homework

    Homework

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