I want to transport one array(arr1) into another array(arr3), but don’t transport the integers that are in another array (arr2), so if a number from arr1 is not in arr 2 then put it in arr3 if it is part of arr2 skip it and don’t add it to arr3

This is what I got, but it doesn’t work I think because of the for loop for(int l=0;l<arr2.length;l ), but I can’t find another solution that works.

int[] arr3 = new int[arr1.length - arr2.length];

for (int i = 0; i < arr1.length; i  ) {

    for(int l=0; l<arr2.length; l  ) {

        if (arr[i] != arr2[l]) {
            arr3[j] = arr[i];
        }
    }
}

CodePudding user response：

Since your second FOR loop is not checking for all the items in the second array, it will not give you correct result.

Create a helper function which will iterate the whole array to check if a number is present in the array or not. like this

boolean containsTarget(int[] array, int target){
    for(int i = 0; i < array.length; i  ){
        if(array[i] == target){
            return true;
        }
    }
    return false;
}

and then call this function inside your first FOR loop to perform the check.

List<Integer> arr3 = new ArrayList<Integer>(); //Using arraylist because i am not sure what will be the size of the final array.

for (int i = 0; i < arr1.length; i  ) {

    if(!containsTarget(arr2, arr1[i])){
        arr3.add(arr1[i]);
    }
}

I haven't tested this code but on a higher level this logic should work.

CodePudding user response：

you idea have some issue for loop condition. the follow code .i test

public static void main(String[] args) {
      
        int[] arr1 = {1, 2, 3, 4, 5};
        int[] arr2 = {3, 4};
        int[] test = test(arr1, arr2);
        System.out.println(test);
    }
private static int[] test(int[] arr1,int[] arr2){

        int[] arr3 = new int[arr1.length - arr2.length];
        int j=0;
        for (int i = 0; i < arr1.length; i  ) {

            boolean flag=true;
            for(int l=0; l<arr2.length; l  ) {

                if (arr1[i] == arr2[l]) {
                    flag=false;
                    break;
                }
            }
            if (flag){
                arr3[j] = arr1[i];
                j  ;
            }
        }
        return arr3;
    }

the output value {1,2,5} I guess the result which you want get .