Replace string in ArrayList

Question

I am string to replace a string in a column ArrayList. I am getting an error on the expression

Bad return type in lambda expression: String cannot be converted to Articles

articlesArrayList.replaceAll(articles -> articles.getAuthor().replace("."," "));

Answer 1

The replaceAll method is trying to return an array of articles. Your function map is returning a string instead. If you want to replace the '.' character with ' ' for each author, use the ArrayList.forEach method instead.

Answer 2

class Main {
    public static void main(String[] args) {
        new Main().replace();
    }

    public void replace() {
        List<Article> articlesArrayList = new ArrayList<>();
        articlesArrayList.add(Article.builder().author("Sagar.Gangwal").build());
        articlesArrayList.stream().forEach(article -> article.getAuthor().replaceAll(".", " "));

        articlesArrayList = articlesArrayList.stream()
                .map(a -> this.update(a)).collect(Collectors.toList());
        System.out.println(articlesArrayList.get(0));
    }

    private static Article update(Article a) {
        a.author = a.getAuthor().replaceAll("\\.", " ");
        return a;
    }
}

You can see above code.

Here i am trying to create stream and then foreach element of that stream i want to update AuthorName with '.' to space.

articlesArrayList.stream().map(a -> this.update(a)).collect(Collectors.toList());

You need to use stream API and then custom update method to update value.

Also for replacing '.' , you need to use escape character as well. replaceAll method of String class contains first argument as regular expression .

If you see this , i am escaping '.' with '\\\\.' . a.getAuthor().replaceAll("\\\\.", " ");

So instead of replaceAll , you can go with replace method which simply take first argument as simply replace one character with passed target character.

You can see difference between replace and replaceAll.