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Java Java Data Structures Exploring the Java Collection Framework ArrayLists

Alex Kasper
Alex Kasper
1,896 Points
Posted by Alex Kasper
Alex Kasper
1,896 Points

Java - ArrayLists - why are array lists not being recognized after importing?

I have my ArrayList imported at the start of the code but I keep on getting compiler errors saying that the List is not a recognized symbol... do I need to declare my list under blogpost directly?

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

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

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 List<String> getExternalLinks() {
    List<String> results = new ArrayList<String>();
    for (String word : getWords()) {
      if (word.startsWith("http")) {
        results.add(word);
      }
    }
    return results;
  }
}
Jeremy Hill
Jeremy Hill
29,567 Points

I just passed the challenge with this code. Yours doesn't look that much different; may just need to add the word "this." to your getWords() in your for loop.

Here is my code:

public List<String> getExternalLinks(){
    List<String> links = new ArrayList<String>();
    for(String word : this.getWords()){

      if(word.startsWith("http"))
        links.add(word);
    }
    return links;
  }

2 Answers

Kourosh Raeen
Kourosh Raeen
23,733 Points
Kourosh Raeen
Kourosh Raeen
23,733 Points

You need to import List as well:

import java.util.List;
Jeremy Hill
Jeremy Hill
29,567 Points

I didn't think to check for that one import. That is kind of important lol.

Alex Kasper
Alex Kasper
1,896 Points
Alex Kasper
Alex Kasper
1,896 Points

yep, it was importing the list. Thanks for the help. Though that I didn't need to because I added in the ArrayList.