Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Java Java Data Structures Exploring the Java Collection Framework ArrayLists

Jack Cummins
Jack Cummins
17,417 Points
Posted by Jack Cummins
Jack Cummins
17,417 Points

Why is my answer wrong? I give out best answers if you give me a good answer.

Assignment: Let's add a method that returns a list of all links in the body of the document. All words that start with http should be considered links. Name it getExternalLinks.

NOTE: Remember to import the needed classes from java.util. HINT: We already made the getWords method, we should use it!

Thanks! Jack

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

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

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 List<String> getExternalLinks (){
    List<String> results = new ArrayList<String>();

    for (String word : getWords()){
      if word.startsWith("http"){
        results.add(word)
      }
    }
  }

  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 getExternalLinks(){

  }
}

2 Answers

Amanda Allison
Amanda Allison
9,104 Points

Looks really close! There are a couple of things that need to be adjusted. To get a better idea of the issues, you can click on the "Preview" button in the challenge and you'll see a few syntax errors.

  • You'll want to wrap your if statement in parentheses like this:
if (word.startsWith("http"))
  • You'll need to add a semicolon to the end of your results.add(word) call:
results.add(word);
  • Make sure to return results at the end of the getExternalLinks method:
return results;
  • It looks like there's an extra getExternalLinks method at the end of the file that needs to be removed:
  public getExternalLinks(){

  }
Sean M
Sean M
7,344 Points
Sean M
Sean M
7,344 Points

This answer is for future reference to students. It definitely took me some time to fully grasp this one.

  1. Creating a public class that is a list of strings. This class is named getExternalLinks

    public List<String> getExternalLinks() {

  2. Introducing the list that will contain strings. We will name the lists "results". This information is a new Array List that will contain Strings.

    List<String> results = new ArrayList<String>();

  3. for each word, which is a string, we want to get every word (to check if it has htttp which is the next step)

    for (String word: getWords()) {

  4. If the word starts with "http", add the word. 

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