how to copy array in java
// method 
public static int [] copyArray(int [] arr){
      int [] copyArr = new int[arr.length];
      for (int i = 0; i < copyArr.length; i++){
            copyArr[i] = arr[i];
       }
      return copyArr;
}
// Arrays. method 
int[] copyCat = Arrays.copyOf(arr, arr.length);
// System 
System.arraycopy(x,0,y,0,5); // 5 is array's length 
// clone 
y = x.clone();
