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

Posted by mayur lalwani
mayur lalwani
992 Points

Cannot find error

Cannot find error

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

import java.io.Serializable;
import java.util.Date;
import java.util.Arrays;
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 int compareTo(BlogPost other) {
    if (equals(other)) {
      return 0;
    }
    return mCreationDate.compareTo(other.mCreationDate);
  }

  public List<String> getExternalLinks(){
    return getWordsPrefixedWith("http");
  }

  public List<String> getWordsPrefixWith(String prefix){
    List<String> results = new ArrayList<String>();
    for(String words : getWords()){
      if(words.startswith(prefix)){
        results.add(words);
      }
    }
    return results;

  }


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

  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;
  }
}
Oshedhe Munasinghe
Oshedhe Munasinghe
8,108 Points

hi is it about to do something with method getWords???

1 Answer

jcorum
jcorum
71,830 Points
jcorum
jcorum
71,830 Points

The first problem is that the split() method returns an array, so you need to assign the result of mBody.split(...) to an array. Your code was missing the assignment operator, and you were trying to assign an array to a String, not to a String array. Once you make words an array, you just need to return it, not Arrays.asList(words)

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

The next error is just a typo: You call the getWordsPrefixedWith() method, but the name of the method is getWordsPrefixWith()

  public List<String> getExternalLinks(){
    return getWordsPrefixedWith("http");
  }

  public List<String> getWordsPrefixWith(String prefix){ ...

The next error is in the getWordsPrefixWith() method. You have:

if(words.startswith(prefix)){

But the String method is startsWith() -- camel case, not starts with()

With these corrections it now compiles.