AP CSA 4.2 Exercise 1: For Each, Not For i

Unit 4: Data Collections · Lesson 4.2 · Exercise 1

For Each, Not For i

Introduction to Using Data Sets. Write real Java, run it, and submit it to be graded against hidden test cases.

Back to the Lesson 4.2 page All Unit 4 lessons

Why this one is worth doing

The enhanced for loop hands you the values and never the positions. That makes it the right tool for a total and the wrong tool the moment you need to know where you are, which is the distinction this exercise is built around.

What to write

The array is built for you from the input. Do not change that part.
Using an ENHANCED for loop, print the sum of the values.
Using an enhanced for loop, print how many of them are odd.
Using an enhanced for loop, print the largest value.
On the last line print the number of values, which the array itself can tell you.

Your program reads

An integer count, then that many integers.

Your program prints

Four lines: the sum, the count of odd values, the largest value and how many values there were.

Worked examples

These are the cases you can see. There are more you cannot, and they use different values, so an answer that prints these numbers as constants will fail.

Example 1 input

5
4 7 2 9 1

Example 1 output

Example 2 input

1
6

Example 2 output

Your answer

Main.java

import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner input = new Scanner(System.in);
    int count = input.nextInt();
    int[] data = new int[count];
    for (int i = 0; i < count; i++) {
      data[i] = input.nextInt();
    }

    // From here on, use for (int value : data) and not an index.
  }
}

Input for the Run button

Run sends whatever is in the input box below. Submitting runs your program against every test case, including hidden ones with different input.

Stuck?

Hint 1

for (int value : data) reads every element in order. There is no i, and you do not need one for any of these three answers.

Hint 2

data.length is a field, not a method, so there are no parentheses after it.

Hint 3

A negative odd number is still odd. value % 2 != 0 is true for -3, while value % 2 == 1 is not.

Where to go next

Rework the Lesson 4.2 page Pick another Unit 4 lesson

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