Find lowest matching values in Java

Question

I created this program that allows the user to input 5 numbers for array 1 and 5 numbers for array 2, the idea of the program is to iterate through those arrays and find the matching values for example: user types on input 1 = 1, 2, 3, 4 and 5 and the same for input 2, the lowest matching value is 1 and my program does that, if there is no matching value displays a message that there is no matching values and my program does that. However, if the user inputs something like this on 1 = 3, 4, 5, 7, 2 and input 2 = 9, 12, 8, 7, 15, what my program does in this case, variable min1 on array1 find lowest value which is 2 and variable min2 on array2 find lowest value which is 7 so in theory does not match, but they are asking me to find the lowest MATCHING values so both of them have 7 so it should display 7, I have some code there that select the 7 on each array and display them, now I have to figure out how to add that temporal variable into the displays so it only displays one or the other, as of now it displays 7 and then no matching value, tried adding it to the if statement but couldn't make it

import java.util.Scanner;
public class SmallestArrayItem {

    public static void main(String[] args) {
        
        Scanner keyboard = new Scanner(System.in);
        
        int array1[] = new int[5];
        int array2[] = new int[5];
        
        System.out.println("Please enter 5 values for array 1");
        
        for(int i = 0; i < array1.length; i++) {
            int userInput = keyboard.nextInt();
            array1[i] = userInput;
        }
        
        System.out.println("Please enter 5 values for array 2");
        
        for(int i = 0; i < array2.length; i++) {
            int userInput = keyboard.nextInt();
            array2[i] = userInput;
        }
        
        int min1 = array1[0];
        
        for(int index1 = 1; index1 < array1.length; index1++) {
            if(array1[index1] < min1) {
                min1 = array1[index1];
            }
        }
        
        int min2 = array2[0];
        
        for(int index2 = 1; index2 < array2.length; index2++) {
            if(array2[index2] < min2) {
                min2 = array1[index2];
            }
        }
        
        int tmpval = Integer.MAX_VALUE;
        for(int i = 0; i < array1.length; i++){
            for(int j = 0; j < array2.length; j++){
                if(array1[i] == array2[j]){
                    // same value
                    if(tmpval > array1[i]){
                        tmpval = array1[i];
                    }
                }
            }
        }
        System.out.println(tmpval);
        
        
        if(min1 == min2) {
            System.out.println("The Smalest match in the array is : " + min1);
        } else if(min1 != min2) {
            System.out.println("There is no smallest matching integer!");
        }
    }
    
        

}

Answer 1

Thanks for all your help guys, this is the final code:

public class SmallestArrayItem {

    public static void main(String[] args) {
        
        Scanner keyboard = new Scanner(System.in);
        
        int array1[] = new int[5];
        int array2[] = new int[5];
        
        System.out.println("Please enter 5 values for array 1");
        
        for(int i = 0; i < array1.length; i++) {
            int userInput = keyboard.nextInt();
            array1[i] = userInput;
        }
        
        System.out.println("Please enter 5 values for array 2");
        
        for(int i = 0; i < array2.length; i++) {
            int userInput = keyboard.nextInt();
            array2[i] = userInput;
        }
        
        int minIdx = -1;
        for(int i = 0; i < array1.length; i++) 
        {
            for(int j = 0; j < array2.length; j++) 
            {
                if(array1[i] == array2[j] && (minIdx < 0 || array1[i] < array1[minIdx]))
                {
                    minIdx = i;
                }
            }
        }

        if(minIdx < 0)
            System.out.println("There is no smallest matching integer!");
        else
            System.out.println("The Smallest match in the array is : " + array1[minIdx]);
    
    }
}

Answer 2

It's not clear from your description if the matching values have to be at the same position in the two arrays. If we assume that they do then something like this would work:

int[] arr1 = {3,4,5,7,2};
int[] arr2 = {9,12,8,7,15};

int minIdx = -1;
for(int i = 0; i < arr1.length; i++) 
{
    if(arr1[i] == arr2[i] && (minIdx < 0 || arr1[i] < arr1[minIdx]))
    {
        minIdx = i;
    }
}

if(minIdx < 0)
    System.out.println("No match");
else
    System.out.println("Min match: " + arr1[minIdx]);

Note how we use a negative index as an indicator that we haven't found a match. The standard trick of using Integer.MAX_VALUE as our starting value isn't really safe as it could be a matching value in the array.

If the matching values can appear at any position in the arrays then you'll need to compare each value in array1 with every value in array2:

for(int i = 0; i < arr1.length; i++) 
{
    for(int j = 0; j < arr2.length; j++) 
    {
        if(arr1[i] == arr2[j] && (minIdx < 0 || arr1[i] < arr1[minIdx]))
        {
            minIdx = i;
        }
    }
}

Answer 3

Your code look great, its just a problem with your logic. In your question, you talked about nesting for loops, so you were on the right track.

int[] arr1 = {3,4,5,7,2};
int[] arr2 = {9,12,8,7,15};

int tmpval = Integer.MAX_VALUE;
for(int i = 0; i < arr1.length; i++){
    for(int j = 0; j < arr2.length; j++){
        if(arr1[i] == arr2[j]){
            // same value
            if(tmpval > arr1[i]){
                tmpval = arr1[i];
            }
        }
    }
}
System.out.println(tmpval);