Enhanced For Loop (For-each)
- Pros
- Cons
Regular For Loop
Enhanced For Loop
Comparing a regular for loop with the enhanced for loop
Hacks

Enhanced For Loop (For-each)

An enhanced For Loop is a simplified version of a regular for loop, where the coder doesn’t need to specify the increment and can access each element directly.

Pros

Can access the elements of a array instad of a counter
Enhanced readability
Less likely to be buggy

Cons

Can only traverse the array in order
Accesses a copy of the array, so modifications to the variables are not saved in the original array

Regular For Loop

Enhanced For Loop

int[] numbers = {10, 20, 30, 40, 50};
for (int number : numbers) {
    number += 1;
    System.out.println(number);
};

System.out.println(Arrays.toString(numbers))

11
21
31
41
51
[10, 20, 30, 40, 50]

Comparing a regular for loop with the enhanced for loop

Popcorn Hack: Rewrite this code to use an enhanced for loop instead. make comments explaining what you added/changed

String[] languages = {"Java", "Python", "Markdown", "C++", "Go", "JavaScript", "HTML"};

for (int i = 0; i<languages.length; i++) {
    System.out.println(languages[i]);
};

Java
Python
Markdown
C++
Go
JavaScript
HTML

Hacks

Build the loop
Multiple Choice
Find each index of the letter ‘a’ in each word
Find the error
HW Hack

public class Main {
    public static void main(String[] args) {
        // Add an array here
        String[] myArray = {"Math", "PE", "English", "CSA", "Science"};
        
        // Add a loop to go through the array here
        for (String element : myArray) {
            System.out.println(element);
        }
    }
}
Main.main(null);

Math
PE
English
CSA
Science

private String[] myArray = {
    "And", "Table", "Shirts", "Tea", "School Day"
};

for (String currentWord : myArray) {
    // Add code here
}

A: System.out.println(myArray.currentWord.length());
B: System.out.println(myArray[index].length());
C: System.out.println(myArray[currentWord].length());
D: System.out.println(currentWord.length());
//*** IT'S OPTION D ***

String[] fruits = {"Apple", "Banana", "Orange"};

for (String fruit: fruits) {
    // Find the index of the letter 'a' in each fruit
};

public class Main {
    public static void main(String[] args) {
        String[] fruits = {"Apple", "Banana", "Orange"};
        
        for (String fruit : fruits) {
            // Find the index of the letter 'a' in each fruit
            int index = fruit.toLowerCase().indexOf('a');
            System.out.println("The index of 'a' in " + fruit + " is: " + index);
        }
    }
}
Main.main(null);

The index of 'a' in Apple is: 0
The index of 'a' in Banana is: 1
The index of 'a' in Orange is: 2

String[] myArray = {"Object 1", "Object 2", "Object 3", "Object 4", "Object 5"};

for (currentWord: myArray) {
    System.out(currentWord)
};

// There are 3 errors, can you find them?

public class Main {
    public static void main(String[] args) {
        String[] myArray = {"Object 1", "Object 2", "Object 3", "Object 4", "Object 5"};
        
        for (String currentWord : myArray) {
            System.out.print(currentWord);  // You can use println() if you want each on a new line
        }
    }
}
Main.main(null);

Object 1Object 2Object 3Object 4Object 5

Final Hack

Add to the code below to create a average grade calculator (using an enhanced for loop)

Integer[] grades = {88, 93, 55, 68, 77};

Scanner userGrades = new Scanner(System.in);
System.out.print("Enter a grade: ");
int grade = Integer.parseInt(userGrades.nextLine());

// Add code here to take the average

grades = Arrays.copyOf(grades, grades.length + 1);
grades[grades.length - 1] = grade;
System.out.println(Arrays.toString(grades));

Enter a grade: [88, 93, 55, 68, 77, 88]

Homework down below…

public class AverageGradeCalculator {
    public static void main(String[] args) {
        Integer[] grades = {88, 93, 55, 68, 77};

        Scanner userGrades = new Scanner(System.in);
        System.out.print("Enter a grade: ");
        int grade = Integer.parseInt(userGrades.nextLine());

        // Add code here to take the average
        int sum = 0;
        for (int g : grades) {
            sum += g;  
        }
        double average = (double) sum / grades.length;
        System.out.println("Average grade before adding new grade: " + average);

        grades = Arrays.copyOf(grades, grades.length + 1);
        grades[grades.length - 1] = grade;
        System.out.println("Updated grades: " + Arrays.toString(grades));
    }
}

AverageGradeCalculator.main(null);

Enter a grade: 

Average grade before adding new grade: 76.2
Updated grades: [88, 93, 55, 68, 77, 85]