how to copy an array to another array efficiently code example

Example 1: java copy array

int[] a = {1, 2, 3};      
int[] b = a.clone();

Example 2: 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();