CODEWITHSUNDEEP
java
cruella devil
cruella devil

Reputation: 43

How can I make this for loop repeatedly go through a list of arrays until a condition is reached?

I have this method that searches a list of arrays of type Person and deletes a specific one based on the first name.

It works fine.

But it only deletes one person and then stops.

        public void deleteFriend(String firstName){
                Person friendToDelete = null;
                for(Person f : friendsList){
                    if(f.getFirstName().equalsIgnoreCase(firstName)){
                        friendToDelete = f;
                    }
                }
                if(friendToDelete != null){
                    friendsList.remove(friendToDelete);
                    System.out.println("Friend deleted.");
                }
        }

Say my list friendsList has two people with the first name Shane. I want my method to delete all Shanes.

I have tried the following:

    public void deleteFriend(String firstName){
        //Person friendToDelete = null;
        for(Person f : friendsList){
            if(f.getFirstName().equalsIgnoreCase(firstName)){
                friendsList.remove(f);
                continue; 
            }
        }
    }

In the above example, I tried some variations of the if loop. First, I tried break; instead of continue;. I also tried removing that line altogether.

if(f.getFirstName().equalsIgnoreCase(firstName))
                friendsList.remove(f);

It still only deleted the first Shane.

I tried to make a condition to check if there are instances of Person with the first name Shane and while that is true, go through the list with for(Person f : friendsList) and remove it. And then check if there still is a Shane, and do it again.

But I can tell that what I have isn't going to work:

        public void deleteFriend(String firstName){
                //Person friendToDelete = null;
                for(Person f : friendsList){
                    int cond = 0;
                    while(cond == 0){
                        if(f.getFirstName().equalsIgnoreCase(firstName)){
                            friendsList.remove(f);
                        }
                        else{
                            // ??? cond = 1?
                        }
                    }
                }
        }

Can someone help me with what I'm trying to do or point me in the right direction?

Upvotes: 0

Views: 67

Answers (2)

Jorge Campos
Jorge Campos

Reputation: 23381

You can use Java 8 method Collection.removeIf(), expecting a Predicate, to do so and make your code waaaaay simpler.

To perform a delete operation in a list based on a certain condition, just do:

friendsList.removeIf(p -> p.getFirstName().equalsIgnoreCase(firstName));

Here is a bit of more on it: Operating and Removing an Item - Collection.removeIf

Upvotes: 5

Adrian Patterson
Adrian Patterson

Reputation: 105

One way to do this would be to iterate over the friends list using indexing like so:

int index = 0;
for(int i = 0; i < friendsList.length; i++) {
    if(!friendsList[i].getFirstName().equalsIgnoreCase(firstName)) {
        friendsList[index++] = friendsList[i];
    }
}

return Arrays.copyOf(friendsList, index);

As seen in this Geeks for Geeks page. Check it out for other options, like filtering your list (which is much simpler & quicker).

Upvotes: 0

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