finding common elements in two integer arrays java

Question

The code returns 0 and the common numbers more than once. I want it to return an array with the common numbers once! So how do I return an array with numbers that are common to both arrays. I want to return {2,7,4} - something like this. I keep getting out of bounds exceptions when I try to return an array. Thanks, Barry

public class Test {
    public int findCommonElement(int[] a, int[] b){
        int counter=0;
        int temp= 0;
        int tempCounter = 0;
        for(int i=0; i<a.length; i++){
            temp=a[i];
            tempCounter=0;
            for(int j=0; j<b.length; j++){
                if (temp==b[j]){
                    tempCounter++;  
                }

            }

            if (tempCounter == 1) {
                temp = a[i];

                counter++;

                System.out.println(temp);

            }

        }

        return 0;
    }

    public static void main(String []args){
        int myArray[] = {2,2,7,7,2,1,5,4,5,1,1};
        int myArray2[] = {2,3,4,7,10};


        Test hello = new Test ();
        System.out.println(hello.findCommonElement(myArray, myArray2));

    }
}

Answer 1

an alternative solution for findCommonElement method

public int[] findCommonElement(int[] a, int[] b){
    List<Integer> array = new LinkedList<Integer>();
    Set<Integer> set = new HashSet<Integer>();
    for(int ele:a){
        set.add(ele);
    }

    for(int ele:b){
        if(set.contains(ele)){
            array.add(ele);
        }
    }

    int[] arr = new int[array.size()];
    for(int i = 0; i < array.size();i++){
        arr[i] = array.get(i);
    }
    return arr;
}