Unit 6 Collegboard Arrays

arrays -array: type of data structure -array and arrayLists are different -ex of declaration: int [] array = new int [10];

- other ways:
- final int length = 10, int[] numbers = new int 
- int length = in.nextInt();, double[] data = new double[length]
- int[squares]= {0,1,2,3,4}

-common errors:

• bound error: trying to access a variable that doesnt exist -uninitialized and unfiled arrays -traverse an array: use any sort of loop but for loops are easiest to access
• int i=0; i<array.length; i++
• enhanced for loops -- can use basic for loop to visit all elements in an array

vocab

• enahnced for loops - the header includes a variable referred to as the enhanced for variable -- assigning a new value to the enhanced for loop does not change the value stored in the array

public class Array
{
    private static int [] values = {1,2,3,4,5};

    public void printValues(){
        for(int i = 0; i < values.length; i++){
            System.out.println(values[i]);
        }

    }


    public void swapFirstAndLast()
    {
        int lastElement = values[values.length-1];
        values[values.length-1] = values[0];
        values[0] = lastElement;
    }

    public void allZero()
    {
        for(int i=0; i < values.length; i++){
            values[i] = 0;
        }
        
    }

    public static boolean isSorted(int[] a) {
       
        for (int i = 0; i < a.length - 1; i++) {
            if (a[i] > a[i + 1]) {
                return false; 
            }
        }
    
        return true; 
    }
    

    public static void main(String[] args){
        System.out.println("Swapping elements:");
        Array swapFirstAndLast = new Array();
        swapFirstAndLast.swapFirstAndLast();
        swapFirstAndLast.printValues();

        System.out.println("Replacing elements with zero:");
        Array allZero = new Array();
        allZero.allZero();
        allZero.printValues();

        System.out.println("are the orginal values sorted in increasing order?");
        System.out.println(isSorted(values));


    }


}

Array.main(null);

Swapping elements:
5
2
3
4
1
Replacing elements with zero:
0
0
0
0
0
are the orginal values sorted in increasing order?
true