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Java Java Data Structures - Retired Exploring the Java Collection Framework ArrayLists

corredius yarbrough
corredius yarbrough
3,167 Points
Posted by corredius yarbrough
corredius yarbrough
3,167 Points

Need help with ArrayList challenge.

Hello, my code passes through the compiler with no syntax errors but the challenge keeps telling me " Remember, best practice states that you should return a List interface, in case you later want to change the implementation. Received class java.util.ArrayList." I been stuck for 45 minutes please help.

com/example/BlogPost.java 
package com.example;

import java.io.Serializable;
import java.util.Date;
import java.util.ArrayList;

public class BlogPost implements Comparable<BlogPost>, Serializable {
  private String mAuthor;
  private String mTitle;
  private String mBody;
  private String mCategory;
  private Date mCreationDate;

  public BlogPost(String author, String title, String body, String category, Date creationDate) {
    mAuthor = author;
    mTitle = title;
    mBody = body;
    mCategory = category;
    mCreationDate = creationDate;
  }

  public int compareTo(BlogPost other) {
    if (equals(other)) {
      return 0;
    }
    return mCreationDate.compareTo(other.mCreationDate);
  }

  public String[] getWords() {
    return mBody.split("\\s+");
  }

  public String getAuthor() {
    return mAuthor;
  }

  public String getTitle() {
    return mTitle;
  }

  public String getBody() {
    return mBody;
  }

  public String getCategory() {
    return mCategory;
  }

  public Date getCreationDate() {
    return mCreationDate;
  }

  public ArrayList<String> getExternalLinks (){
   ArrayList<String> link = new ArrayList<String>();
    for (String word : getWords()){
      if (word.startsWith("http")){
        link.add(word);
      }
    }
    return link;
  }
}
corredius yarbrough
corredius yarbrough
3,167 Points
corredius yarbrough
corredius yarbrough
3,167 Points

I figured it out. I had to remove Array from my title.

1 Answer

Mihai Craciun
Mihai Craciun
13,520 Points
Mihai Craciun
Mihai Craciun
13,520 Points

The way you can solve this is to replace the ArrayList<> declaration to a List<>. This way you can use any class that implements the List interface such as ArrayList LinkedList or Stack any time without changing the method type and much code later on.

So in the end your method should look something like this (please remember to import java.util.List):

  public List<String> getExternalLinks (){
   List<String> link = new ArrayList<String>();
    for (String word : getWords()){
      if (word.startsWith("http")){
        link.add(word);
      }
    }
    return link;
  }