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

Charles Harpke
Charles Harpke
33,986 Points
Posted by Charles Harpke
Charles Harpke
33,986 Points

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 b

I get the 4 errors:

Errors: private List getExternalLinks(){ ^ ./com/example/BlogPost.java:58: error: class, interface, or enum expected for (String words:getWords()){ ^ ./com/example/BlogPost.java:61: error: class, interface, or enum expected } ^ ./com/example/BlogPost.java:64: error: class, interface, or enum expected

Here is my code:

package com.example;

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

private List<String> getExternalLinks(){
    List<String> links = new ArrayList<String>();
    for (String words:getWords()){
      if(words.startsWith("http")){
        links.add(words);
      }
    }
    return links;
}
com/example/BlogPost.java 
package com.example;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Date;
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 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> links = new ArrayList<String>();
    for (String words:getWords()){
      if(words.startsWith("http")){
        links.add(words);
      }
    }
    return links;
}
Charles Harpke
Charles Harpke
33,986 Points
Charles Harpke
Charles Harpke
33,986 Points

like so?

package com.example;

import java.io.Serializable;
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 List<String> getExternalLinks(){
    List<String> links = new ArrayList<String>();
    for (String words:getWords()){
      if(words.startsWith("http")){
        links.add(words);
      }
    }
    return links;
  }

  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;
  }
}

3 Answers

Rob Bridges
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Rob Bridges
Full Stack JavaScript Techdegree Graduate 35,467 Points
Rob Bridges
.a{fill-rule:evenodd;}techdegree seal-36
Rob Bridges
Full Stack JavaScript Techdegree Graduate 35,467 Points

Hey Charles,

It looks like your method is declared outside of the class, the coding in it is fine, just have it be underneath the constructor and you should be good.

Thanks, I hope this helps.

Matt Bloomer
Matt Bloomer
10,608 Points
Matt Bloomer
Matt Bloomer
10,608 Points

I understand the answer except for the line: List<String> links = new ArrayList<String>();

Can you please explain that a little more? The interface is on the left and the implementation is on the right; this is where we convert the string to an array list and then use the getWords method to search for anything that has a http, correct?