Comparing Two Integer Arrays in Java

Comparing two integer arrays in Java

public static void compareArrays(int[] array1, int[] array2) {
        boolean b = true;
        if (array1 != null && array2 != null){
          if (array1.length != array2.length)
              b = false;
          else
              for (int i = 0; i < array2.length; i++) {
                  if (array2[i] != array1[i]) {
                      b = false;    
                  }                 
            }
        }else{
          b = false;
        }
        System.out.println(b);
    }

How to compare int arrays in Java?

A few things to note here:

• == compares the references, not the values . . . that is, you are asking whether these two arrays are the same exact instance, not whether they contain the same values.
• The fact that you are using == means you may not know about the equals() method on Object. This is not the method you'll need to solve this current problem, but just be aware that in general, when you compare the values of two objects, you should be using obj1.equals(obj2), not obj1 == obj2. Now == does work with primitives like int (e.g. plain old x == 3 and so on), so maybe that's why you were using it, but I just wanted to make sure you were aware of equals() vs. ==.
• In the old old days (pre-1998), you would have to compare each element pair of the two arrays. Nowadays, you can just use that static Arrays.equals() method on the java.util.Arrays class. This method is overloaded for all the primitive types (using == under the hood for each element pair) and for Object (where it will most definitely use equals() for each pair.)

How do you compare two int arrays elements separately in Java and see which is the greater element?

You need 2 variables that holds each ones score, increment the one that has the bigger card for each round, at the end find the biggest score

int[] playerOne = {10, 6, 8, 9, 7, 12, 7};
int[] playerTwo = {7, 6, 9, 5, 2, 8, 12};

int scorePlayerOne = 0, scorePlayerTwo = 0;

for (int i = 0; i <= playerOne.length - 1; i++) {
    if (playerOne[i] < playerTwo[i]) {
        scorePlayerTwo++;
    } else if (playerTwo[i] < playerOne[i]) {
        scorePlayerOne++;
    }
}

if (scorePlayerOne < scorePlayerTwo) {
    System.out.println("Player Two wins");
} else if (scorePlayerTwo < scorePlayerOne) {
    System.out.println("Player One wins");
} else {
    System.out.println("Draw");
}

How can I compare two integers in one array in Java?

you are expecting it to check just the next element, but you are checking next element to the end

This is what is happening with your current code

1,5,6,4,3,10

5 > 4
5 > 3
6 > 4
6 > 3
4 > 3

and so count = 5

remove inner loop and change condition to

if (t[i] < t[i+1]){
    sum += 1;
}

Compare two integer arrays using Java Stream

You may do it like so,

List<Boolean> equalityResult = IntStream.range(0, a.length).mapToObj(i -> a[i] == b[i])
                .collect(Collectors.toList());

Precondition: both the arrays are of same size.

Compare two integer arrays for similar values

Using streams you can do something like:

import java.util.Arrays;

public class Test {
    public static void main(String[] args){            
        int[] x = {0,1,4,7,8,9};
        System.out.println(matchArrays(x));
    }
    public static int matchArrays  (int[] x) {
        int[] y = {1,2,3,5,7,7,8};
        return (int)Arrays.stream(x).filter(i->Arrays.stream(y).anyMatch(j->j==i)).count();
    }
}

Java: how to compare two int[] arrays for non duplicate elements?

You can use binary search to compare arrays and find differences. You need to do that comparison as two-way(<- ->) like:

array1 --> array2  and  array2 --> array1

Because you need to sum up differences of sets. Let A and B our sets, we need to find:

(A-B) U (B-A)

The binary search solution is below. Complexity of that algorithm is O(log n)

private static int getDifferenceBetweenTwoArray(int[] array1 , int[] array2)
{
    int differenceCount = 0;
    //if you dont want to sort your original arrays, create temporary arrays
    int temp1[] = Arrays.copyOf(array1 , array1.length);
    int temp2[] = Arrays.copyOf(array2 , array2.length);
    Arrays.sort(temp1);
    Arrays.sort(temp2);

    for(Integer i : temp1)
    {
        if(Arrays.binarySearch(temp2, i) < 0)
            differenceCount++;
    }
    for(Integer i: temp2)
    {
        if(Arrays.binarySearch(temp1, i) < 0)
            differenceCount++;
    }   

    return differenceCount;
}

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