OddOccurrencesInArray

//Odd-Occurrences-Array
	public String oddOccurrencesArraySolution(int[] A) {
        HashMap<Integer,Integer> occurs = new HashMap<>();
        for(int i=0;i<A.length;i++){
           if(occurs.containsKey(A[i]) && occurs.get(A[i]) == 1){
                occurs.remove(A[i]);  
            }else{
                occurs.put(A[i],1);
            }
        }
        String res =  "";
        for(int key : occurs.keySet()){
        	res += key +",";    
        }
        
        //bitwise XOR operator
        int solution = 0;
        for (int value: A)
          solution ^= value;
        System.out.println(solution);
        
        for (int value: A)
            solution &= value;
          System.out.println(solution);
        
        return res.substring(0, res.length()-1);
    }
    
    int[] b = {3,9,3,9,9,7,9};
		System.out.println(obj.oddOccurrencesArraySolution(b));