How to get the minimum and maximum value inside a user-defined array?

Question

I want to get the minimum value and maximum value inside an array. After the user inputs n number of arrays, it will print the minimum and max value inside that array.

Here is an example output

Here is my code so far

public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        try {
            System.out.println("Enter array size: ");
            int n = input.nextInt();

            int [] array = new int[n];
            int max = getMaxValue(array);
            int min = getMinValue(array);

            System.out.println("Enter " + n + " elements:");
            for (int i = 1; i <= array.length; i++) {
                array[i] = input.nextInt();
            }

            System.out.println("Max Value: " + max);
            System.out.println("Min Value: " + min);

        } catch (InputMismatchException e) {
            System.out.println("INVALID INPUT >> PLEASE INPUT A NUMBER");
        }
    }

    private static int getMaxValue(int[] array) {
        int maxValue = array[0];
        for (int i = 1; i < array.length; i++){
            if (array[i] > maxValue){
                maxValue = array[i];
            }
        }
        return maxValue;
    }

    private static int getMinValue(int[] array) {
        int minValue = array[0];
        for (int i = 1; i < array.length; i++){
            if (array[i] < minValue) {
                minValue = array[i];
            }
        }
        return minValue;
    }
}

You have to calculate the maximum and minimum value after you ask the user for input, not before. — Grumblesaurus, Sep 25 '20 at 03:26
You should also put the try/catch closer to the input. The way you have it right now, it breaks the loop if they input badly formed text. — Grumblesaurus, Sep 25 '20 at 03:27
when I run the program, it doesn't show the max and min value in the array. For example, after you input the n numbers of array, the program ends after that but doesn't show the min and max value — WiloWisk, Sep 25 '20 at 03:28
*it doesn't show the max and min value in the array* - because the Array contains no values when you invoke your min/max methods. — camickr, Sep 25 '20 at 03:32

score 0 · Answer 1 · answered Sep 25 '20 at 03:47

There are a few problems keeping this program from working:

getMinValue and getMaxValue should be called after your input loop
All 3 of your loops index starting from 1, they should start from 0
The input loop repeats until i <= array.length, but it should end at i < array.length

Problem 1 is that these method are called on the empty array. Problems 2 and 3 will cause an ArrayIndexOutOfBoundsException.

Here's how the corrections would look in your code:

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        try {
            System.out.println("Enter array size: ");
            int n = input.nextInt();

            int [] array = new int[n];

            System.out.println("Enter " + n + " elements:");
            for (int i = 0; i < array.length; i++) {
                array[i] = input.nextInt();
            }
            int max = getMaxValue(array);
            int min = getMinValue(array);

            System.out.println("Max Value: " + max);
            System.out.println("Min Value: " + min);

        } catch (InputMismatchException e) {
            System.out.println("INVALID INPUT >> PLEASE INPUT A NUMBER");
        }
    }

    private static int getMaxValue(int[] array) {
        int maxValue = array[0];
        for (int i = 0; i < array.length; i++){
            if (array[i] > maxValue){
                maxValue = array[i];
            }
        }
        return maxValue;
    }

    private static int getMinValue(int[] array) {
        int minValue = array[0];
        for (int i = 0; i < array.length; i++){
            if (array[i] < minValue) {
                minValue = array[i];
            }
        }
        return minValue;
    }
}

score 0 · Answer 2 · edited Sep 25 '20 at 07:40

There were 3 problems in your code which are as follows:

int max = getMaxValue(array) int min = getMinValue(array) are called in wrong places

when we initialize an int array the default value present in it is0. So when you had call getMaxValue().
array[0] = 0 is compared with all rest of the values in the array (which are 0) and from all 0 is the maximum.
Same goes for getMinValue().

You have called the function getMaxValue() and getMinValue() without filling the array,with user input. you should have used a for loop from 0 to array.length.

    for(int index = 0 ; index < array.length ; index++){
       array[index] = input.nextInt();
    }

Has you would have noticed, I have index staring from 0 to array size. what you did:

for (int i = 1; i <= array.length; i++) {
   array[i] = input.nextInt();
 }

this will cause ArrayIndexOutOfBoundException Because array indexing starts from 0 to n-1 and you allowed it to run till 1 to n.

Additionally, the finding of min and max can be done in one function. by keeping the return type as an array.

public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        try {
            System.out.println("Enter array size: ");
            int n = input.nextInt();

            int [] array = new int[n];
            
            System.out.println("Enter " + n + " elements:"); // <-- changed
            for (int i = 0; i < array.length; i++) {
                array[i] = input.nextInt();
            }
            
            int max_min[] = getMax_MinValue(array); // <- notice this.
            
            System.out.println("Max Value: " + max_min[0]);
            System.out.println("Min Value: " + max_min[1]);

        } catch (InputMismatchException e) {
            System.out.println("INVALID INPUT >> PLEASE INPUT A NUMBER");
        }finally {
            input.close(); // close the scanner 
        }
    }

    // return type changed 
    private static int[] getMax_MinValue(int[] array) {
       
        int maxValue = array[0];
        int minValue = array[0];
       
        for (int i = 0; i < array.length; i++){

            if (array[i] > maxValue){
                maxValue = array[i];
            }
            if(array[i] < minValue) {
                minValue = array[i];
            }

        }
        
        int min_max[] = {maxValue,minValue}; // min_max[0] has max value and min_max[1] has min value
        return min_max;
    }

Output:

Enter array size: 
8
Enter 8 elements:
5
23
9
14
45
36
42
39
Max Value: 45
Min Value: 5

score 0 · Answer 3 · answered Sep 25 '20 at 07:43

This is not an appropriate answer.

However as the implementations of getMaxValue & getMinValue have a slight flaw: empty arrays will raise an ArrayIndexOutOfBoundException.

And especially one might use the Stream classes.

private static int getMaxValue(int[] array) {
    return IntStream.of(array).max().orElse(0);
}

private static int getMinValue(int[] array) {
    return IntStream.of(array).min().orElse(0);
}

max and min yield an OptionalInt, and for empty arrays one may give a default (orElse).

How to get the minimum and maximum value inside a user-defined array?

3 Answers3