Java 7 Solution

double postiveNum=0,negativeNum=0;

    for(int x : arr)
    {
        if(x>0)
          postiveNum++;
        else if(x<0)
          negativeNum++;

    }
    System.out.printf("%.6f\n",(postiveNum/arr.size()));
    System.out.printf("%.6f\n",(negativeNum/arr.size()));
    System.out.printf("%.6f\n",((arr.size()-(postiveNum+negativeNum))/arr.size()));